groups 1 and 2 - frankly chemistry topic 10 groups 1 and 2 ... sulphates of group 2 carbonates...

15
GROUPS 1 AND 2 AS TOPIC 10 ELECTRONIC CONFIGURATIONS AND PHYSICAL PROPERTIES IONISATION ENERGIES REACTIONS OF THE ELEMENTS WITH OXYGEN AND CHLORINE REACTIONS OF THE ELEMENTS WITH WATER REACTIONS OF THE ELEMENTS WITH DILUTE ACIDS GROUP 2 OXIDES WITH WATER AND DILUTE ACIDS HYDROXIDES OF GROUPS 1 AND 2 CHLORIDES SULPHATES OF GROUP 2 CARBONATES NITRATES FLAME TEST USES OF GROUP 2 COMPOUNDS TEST QUESTION Questionsheet 1 Questionsheet 2 Questionsheet 3 Questionsheet 4 Questionsheet 5 Questionsheet 6 Questionsheet 7 Questionsheet 8 Questionsheet 9 Questionsheet 10 Questionsheet 11 Questionsheet 12 Questionsheet 13 Questionsheet 14 QUESTIONSHEETS AS Level CHEMISTRY 15 marks 17 marks 16 marks 17 marks 13 marks 16 marks 16 marks 15 marks 16 marks 17 marks 17 marks 22 marks 15 marks 11 marks Curriculum Press – Licence Agreement: Paper copies of the A-Level Chemistry Questionsheets may be copied free of charge by teaching staff or students for use within their school, provided the Photocopy Masters have been purchased by their school. No part of these Questionsheets may be reproduced or transmitted, in any other form or by any other means, without the prior permission of the publisher. All rights are reserved. This license agreement is covered by the laws of England and Wales © Curriculum Press March 2008. Curriculum Press • Bank House • 105 King Street • Wellington • Shropshire • TF1 1NU ress urriculum C P www.curriculum-press.co.uk Authors Trevor Birt John Brockington Donald E Caddy Kevin Frobisher Andrew Jones Andy Shepherd Adrian Bond Stuart Barker Editors John Brockington Stuart Barker

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Page 1: GROUPS 1 AND 2 - Frankly Chemistry topic 10 groups 1 and 2 ... sulphates of group 2 carbonates nitrates flame test uses of group 2 compounds test question ... difference 1

GROUPS 1 AND 2AS TOPIC 10

ELECTRONIC CONFIGURATIONS AND PHYSICAL PROPERTIES

IONISATION ENERGIES

REACTIONS OF THE ELEMENTS WITH OXYGEN AND CHLORINE

REACTIONS OF THE ELEMENTS WITH WATER

REACTIONS OF THE ELEMENTS WITH DILUTE ACIDS

GROUP 2 OXIDES WITH WATER AND DILUTE ACIDS

HYDROXIDES OF GROUPS 1 AND 2

CHLORIDES

SULPHATES OF GROUP 2

CARBONATES

NITRATES

FLAME TEST

USES OF GROUP 2 COMPOUNDS

TEST QUESTION

Questionsheet 1

Questionsheet 2

Questionsheet 3

Questionsheet 4

Questionsheet 5

Questionsheet 6

Questionsheet 7

Questionsheet 8

Questionsheet 9

Questionsheet 10

Questionsheet 11

Questionsheet 12

Questionsheet 13

Questionsheet 14

QUESTIONSHEETS AS LevelCHEMISTRY

15 marks

17 marks

16 marks

17 marks

13 marks

16 marks

16 marks

15 marks

16 marks

17 marks

17 marks

22 marks

15 marks

11 marks

Curriculum Press – Licence Agreement:Paper copies of the A-Level Chemistry Questionsheetsmay be copied free of charge by teaching staff or studentsfor use within their school, provided the PhotocopyMasters have been purchased by their school. No part ofthese Questionsheets may be reproduced or transmitted,in any other form or by any other means, without theprior permission of the publisher. All rights are reserved.This license agreement is covered by the laws of Englandand Wales © Curriculum Press March 2008.

Curriculum Press • Bank House • 105 King Street • Wellington • Shropshire • TF1 1NU

ressurriculumCPwww.curriculum-press.co.uk

AuthorsTrevor Birt John BrockingtonDonald E Caddy Kevin FrobisherAndrew Jones Andy ShepherdAdrian Bond Stuart Barker

EditorsJohn BrockingtonStuart Barker

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ELECTRONIC CONFIGURATIONS AND PHYSICAL PROPERTIES

15

a) Define the term s-block element.

....................................................................................................................................................................... [2]

b) (i) What oxidation numbers(s) do the elements of Group 2 display in their compounds?

....................................................................................................................................................................... [1]

(ii) What principal feature do the electronic configurations of these elements have in common?

....................................................................................................................................................................... [1]

c) Give the electronic configurations of a strontium atom and of a calcium cation.

Sr ................................................................................................................................................................... [1]

Ca2+ ............................................................................................................................................................... [1]

Metal Melting temperature / K Density / g cm-3

Group 1 Lithium 453 0.53Sodium 371 0.97Potassium 302 1.90

Group 2 Calcium 1123 1.54Strontium 1041 2.62Barium 987 3.51

TOPIC 10 Questionsheet 1

d) The following table gives some physical properties of six s-block elements.

State and explain how the melting temperatures and densities of the s-block elements vary on progressing downGroups 1 and 2 of the Periodic Table.

Melting temperatures ........................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

Densities ...........................................................................................................................................................

....................................................................................................................................................................... [2]e) Are the atomic radii of s-block elements smaller or larger than the ionic radii of their cations? How do you

account for this?

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

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17

IONISATION ENERGIES

a) Would you expect the first ionisation energy of magnesium to be higher or lower than that of sodium?Explain your answer.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

b) (i) Define the term second ionisation energy and write an equation to show this change.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

(ii) Briefly explain how and why the first and second ionisation energies of the Group 2 elements vary downthe group.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

(iii) Explain why the second ionisation energy of sodium is much greater than that for magnesium

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

c) Use ionisation energies to explain why Group 2 metals are not used as reducing agents in some industrialprocesses as are some Group 1 metals.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

TOPIC 10 Questionsheet 2

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16

REACTIONS OF THE ELEMENTS WITH OXYGEN AND CHLORINE

TOPIC 10 Questionsheet 3

a) Write chemical equations for the combination of magnesium and:

(i) chlorine ................................................................................................................................................ [1]

(ii) oxygen ................................................................................................................................................ [1]

b) Which of the reactions in a) would occur most readily? Give brief reasoning

Reaction ........................................................................................................................................................ [1]

Reasoning ..................................................................................................................................................... [1]

c) Write down the oxidation number of oxygen in Group 2 oxides.

Oxidation number ........................................................................................................................................ [1]

d) Anhydrous calcium chloride can be prepared by passing dry chlorine over heated calcium.

(i) When carrying out this reaction in the laboratory, suggest one important safety precaution.

....................................................................................................................................................................... [1](ii) Why does the chlorine have to be dry?

....................................................................................................................................................................... [1]

(iii) Give the type of bonding in calcium chloride

....................................................................................................................................................................... [1]

(iv) Give a use for calcium chloride in the laboratory

....................................................................................................................................................................... [1]

e) Suggest, giving your reasoning, which of the following oxides: magnesium oxide, strontium oxide, bariumoxide or calcium oxide has the highest melting point:

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

f) A Group 2 bromide contains 20% by mass of the metallic element M. Calculate the relative atomic mass of M.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

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17

REACTIONS OF THE ELEMENTS WITH WATER

a) Under what conditions does water react rapidly with magnesium? State what you would observe and write abalanced chemical equation for the reaction, giving the states of matter for all reactants and products.

Conditions ..................................................................................................................................................... [2]

Observations ................................................................................................................................................. [2]

Equation ........................................................................................................................................................ [2]

b) State the conditions and write a similar chemical equation for the reaction of barium powder with water.

Conditions ..................................................................................................................................................... [1]

Equation ........................................................................................................................................................ [2]

c) State and explain two ways in which the reactions in a) and b) differ from each other.

Difference 1 ................................................................................................................................................... [1]

Explanation ................................................................................................................................................... [1]

Difference 2 ................................................................................................................................................... [1]

Explanation ................................................................................................................................................... [1]

d) (i) In its reaction with water, is sodium more reactive than magnesium or less reactive?

....................................................................................................................................................................... [1]

(ii) Explain your answer to d) (i) in terms of atomic structure.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

TOPIC 10 Questionsheet 4

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13

REACTIONS OF THE ELEMENTS WITH DILUTE ACIDS

a) Magnesium sulfate can be prepared by dissolving magnesium in dilute sulfuric acid and then crystallisingthe solution.

(i) Write two ionic half-equations for this reaction.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Combine the half-equations into an overall ionic equation.

....................................................................................................................................................................... [1]

(iii) Expand this ionic equation into a full chemical equation with state symbols.

....................................................................................................................................................................... [1]

b) (i) Explain why it would not be economic, in the chemical industry, to manufacture magnesium sulfate by themethod in b).

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Given that magnesium occurs naturally as magnesium carbonate (‘magnesite’), suggest, with an equation, acheaper method which could be used to manufacture crystals of magnesium sulfate.

Method ......................................................................................................................................................

...................................................................................................................................................................

............................................................................................................................................................... [2]

Equation ................................................................................................................................................ [1]

c) It is not chemically possible to prepare barium sulfate by dissolving barium in dilute sulfuric acid. Why is this?

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

d) Ignoring economic aspects, explain why it would not be sensible to prepare sodium sulfate by dissolvingsodium in dilute sulfuric acid.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

TOPIC 10 Questionsheet 5

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GROUP 2 OXIDES WITH WATER AND DILUTE ACIDS

16

a) In a series of laboratory experiments, the oxides of Mg, Ca, Sr and Ba were shaken in a test tube withdeionised water. Afterwards, the contents of each test tube were tested with a pH meter and it was found that,on progressing from magnesium oxide to barium oxide, the pH increased from ~7 to ~14.

(i) Why should the pH, in any of these experiments, be greater than 7?

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Write an ionic equation for any reaction that occurs.

....................................................................................................................................................................... [1]

(iii) Explain the increase in pH on progressing from magnesium oxide to barium oxide.

....................................................................................................................................................................... [2]

(iv) State, with your reason, what type of chemical reaction occurs in these experiments.

Type of reaction ..................................................................................................................................... [1]

Reason .......................................................................................................................................................

............................................................................................................................................................... [2]

b) Calcium chloride can be prepared by dissolving either calcium or calcium oxide in hydrochloric acid, yetthese two reactions are of different types. Write the ionic equation for each reaction, then classify it, andfinally justify your classification by discussing the transfer of protons or electrons as appropriate.

Calcium and hydrochloric acid

Ionic equation ................................................................................................................................................ [1]

Classification ................................................................................................................................................. [1]

Justification .......................................................................................................................................................

....................................................................................................................................................................... [2]

Calcium oxide and hydrochloric acid

Ionic equation ................................................................................................................................................ [1]

Classification ................................................................................................................................................. [1]

Justification .......................................................................................................................................................

....................................................................................................................................................................... [2]

TOPIC 10 Questionsheet 6

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HYDROXIDES OF GROUP 1 AND 2

16

a) Give an ionic equation for the reaction between calcium hydroxide and nitric acid

....................................................................................................................................................................... [1]

b) Write balanced chemical equations, with state symbols, for 2 mol of calcium hydroxide reacting with each ofthe following in aqueous solution.

(i) 1 mol of sulfuric acid

....................................................................................................................................................................... [2]

(ii) 2 mol of sulfuric acid

....................................................................................................................................................................... [2]

(iii) 1 mol of ammonium sulfate

....................................................................................................................................................................... [2]

(iv) 1 mol of magnesium nitrate

....................................................................................................................................................................... [2]

c) (i) Write an equation for the action of heat on magnesium hydroxide.

....................................................................................................................................................................... [1]

(ii) On descending Group 2 of the Periodic Table, does the decomposition of hydroxides require lowertemperatures or higher temperatures?

....................................................................................................................................................................... [1]

d) What trend in the solubility of hydroxides in water is observed on descending Group 2? How would thepH of a saturated solution of the hydroxide change down the group?

Trend ............................................................................................................................................................. [1]

pH .................................................................................................................................................................. [1]

e) Calcium hydroxide is sometimes used in crop production.

(i) Suggest the use in question

....................................................................................................................................................................... [1]

(ii) Powdered limestone is also used for this purpose as calcium hydroxide. Suggest two disadvantages ofcalcium hydroxide by comparison.

Disadvantage 1 .................................................................................................................................... [1]

Disadvantage 2 .................................................................................................................................... [1]

TOPIC 10 Questionsheet 7

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CHLORIDES

14

a) (i) Explain the term polarising power of a cation. Describe how the polarising powers of M2+ cations ofGroup 2 vary.

Polarising power ................................................................................................................................... [1]

Variation ............................................................................................................................................... [1]

Explanation .......................................................................................................................................... [1]

(ii) From your answer to (i), suggest which anhydrous Group 2 chloride is covalent and state the geometry ofthis molecule

Chloride ................................................................................................................................................ [1]

Geometry .............................................................................................................................................. [1]

(iii) The polarising power of the cations of lithium and magnesium are similar, despite the ions having differentcharges. How do you account for this?

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

b) Explain why an aqueous solution of magnesium chloride of a given molarity has a pH of 5.5 and an aqueoussolution of sodium chloride of the same molarity has a pH of 7.0.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]Quality of language [1]

c) When recrystallised from water, the chlorides of lithium and of the Group 2 elements contain water ofcrystallisation. The chlorides of the other Group 1 elements do not have water of crystallisation when preparedin this way. Suggest why this occurs.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

TOPIC 10 Questionsheet 8

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SULFATES OF GROUP 2

“The solubility of a salt has a major bearing on its method of preparation.” Illustrate the truth of this statement byoutlining the preparation of:

a) magnesium sulfate (a soluble salt) from magnesium oxide,

b) barium sulfate (an insoluble salt) from barium oxide.

In your answers you should name any reagents which are required, state (but do not describe) the necessarylaboratory techniques, and write chemical equations for the reactions involved.

a) Magnesium sulfate

Reagent(s) and techniques

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

Equation(s)

...........................................................................................................................................................................

....................................................................................................................................................................... [8]

b) Barium sulfate

Reagent(s) and techniques

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

Equation(s)

...........................................................................................................................................................................

....................................................................................................................................................................... [7]

c) What does this suggest about the change in enthalpy of solution for the sulfates on descending Group 2?

....................................................................................................................................................................... [1]

16

TOPIC 10 Questionsheet 9

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CARBONATES

17

a) How do the solubilities of the carbonates of Group 2 elements compare with those of Group 1 elements?Explain why there is a variation.

Comparison .................................................................................................................................................. [1]

Explanation .......................................................................................................................................................

....................................................................................................................................................................... [2]

b) Write balanced chemical equations, including state symbols, for the reactions which occur on heating thefollowing compounds with a Bunsen burner.

Lithium carbonate ......................................................................................................................................... [1]

Sodium carbonate .......................................................................................................................................... [1]

Magnesium carbonate.................................................................................................................................... [1]

c) How would you test for the presence of one of the products of the thermal decomposition of magnesiumcarbonate?

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

d) Magnesium carbonate undergoes thermal decomposition rapidly at around 700 oC. Would the thermaldecomposition of barium carbonate require a higher or lower temperature? Explain your choice.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

e) (i) Describe, with the aid of a chemical equation, what would occur if carbon dioxide were bubbled throughan aqueous solution of radium hydroxide.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

(ii) Suggest what you would observe if dilute hydrochloric acid were added to the reaction mixture obtainedfrom e) (i). Explain your predictions using a chemical equation.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

TOPIC 10 Questionsheet 10

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NITRATES

17

a) The following compounds decompose when they are heated with a Bunsen burner. Write chemical equationsfor each decomposition and state how you could identify any gases evolved.

(i) Lithium nitrate

Equation ................................................................................................................................................ [1]

(ii) Sodium nitrate

Equation ................................................................................................................................................ [1]

(iii) Calcium nitrate

Equation ................................................................................................................................................ [1]

Identification of gases ...............................................................................................................................

............................................................................................................................................................... [3]

b) On heating, 0.253 g of a compound X, known to be either sodium nitrate or potassium nitrate, evolved 30.0cm3 of gas at room temperature and pressure. Identify X and show your working clearly. (Assume that 1 moleof any gas occupies 24.0 dm3 at room temperature and pressure.)

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

c) State and explain the trend in thermal stability of nitrates:

(i) within Group 2.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

(ii) from magnesium to sodium.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

TOPIC 10 Questionsheet 11

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FLAME TEST

22

a) Outline the experimental procedure for carrying out the flame test on solid samples of pure compounds. Givea list of apparatus and reagents needed for this test.

Apparatus ...................................................................................................................................................... [2]

Reagent(s) ...................................................................................................................................................... [1]

Procedure ..........................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

b) Explain how an ion M+ causes a flame colour.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

c) Identify the salts A, B, C, D and E from the following information, and in each case write an equation for thechemical reaction described.

(i) A gives a golden yellow flame, and on heating evolves a colourless gas which relights a glowing splint.

Identity of A ......................................................................................................................................... [1]

Equation ................................................................................................................................................ [2]

(ii) B gives an apple green flame, and in aqueous solution gives a white precipitate with aqueous silvernitrate.

Identity of B ......................................................................................................................................... [1]

Equation ................................................................................................................................................ [2]

(iii) C gives a brick red flame, and on heating gives off a colourless gas which turns limewater milky.

Identity of C ......................................................................................................................................... [1]

Equation ................................................................................................................................................ [1]

(iv) D gives a lilac flame, and in aqueous solution gives a white precipitate with aqueous barium chloride.

Identity of D ......................................................................................................................................... [1]

Equation ................................................................................................................................................ [2]

(v) E gives a crimson flame, and on heating evolves brown fumes.

Identity of E ......................................................................................................................................... [1]

Equation ................................................................................................................................................ [2]

TOPIC 10 Questionsheet 12

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USES OF GROUP 2 COMPOUNDS

15

a) Complete the following table by inserting one major use, in industry, agriculture or medicine, of the compoundsshown.

Calcium hydroxide

Magnesium hydroxide

Calcium carbonate

Magnesium oxide

Barium sulfate

Compound Use

b) (i) Describe how you would carry out the limewater test for carbon dioxide, assuming that you were workingon a small scale with test tubes and a teat pipette but no other apparatus.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

(ii) Explain why, in the limewater test, the ‘milkiness’ disappears in the presence of excess carbon dioxide.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

c) Barium chloride solution is useful in qualitative analysis.(i) What anion is it used to detect?

....................................................................................................................................................................... [1]

(ii) What observation can be expected if that anion is present?

....................................................................................................................................................................... [1]

(iii) Write an ionic equation for the reaction.

....................................................................................................................................................................... [1]

(iv) Why should an aqueous solution be acidified with HCl(aq) before BaCl2(aq) is added to it in this test?

....................................................................................................................................................................... [1]

[5]

TOPIC 10 Questionsheet 13

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TEST QUESTION

11

TOPIC 10 Questionsheet 14

a) The mineral witherite (BaCO3) is a white solid which resembles marble (CaCO

3) in its properties. When a

lump of witherite is heated it turns into a white powder, substance A, which swells up and gives off steamwhen water is added. The product obtained by treating substance A with water is substance B, whichdissolves slightly in water to give an alkaline solution. A saturated aqueous solution of substance B produces awhite precipitate, substance C, when carbon dioxide is bubbled through it.

(i) Give chemical names for substances A, B and C.

A = ......................................................................................................................................................... [1]

B = ......................................................................................................................................................... [1]

C = ......................................................................................................................................................... [1](ii) Write chemical equations for all the chemical reactions occurring in the above account.

A = ......................................................................................................................................................... [1]

B = ......................................................................................................................................................... [1]

C = ......................................................................................................................................................... [1]

b) Excess magnesium carbonate powder was added to dilute sulfuric acid and the mixture was stirred until theeffervescence finished. The suspension was then filtered, leaving a white powder in the filter paper and acolourless solution. The filtrate was left to allow the water to evaporate off, and a white crystalline solid wasproduced.

(i) Write an equation for the chemical reaction.

....................................................................................................................................................................... [1]

(ii) What caused the effervescence?............................................................................................................ [1]

(iii) What was the solid left in the filter paper? ............................................................................................ [1]

(iv) What was the name of the substance which appeared as a white crystalline solid?

....................................................................................................................................................................... [1]

(v) What observations would have been different if magnesium oxide had been used in the place of magnesiumcarbonate?

....................................................................................................................................................................... [1]

C

CO2