year 12 chemistry spring term homework pack name: science... · 2020. 3. 16. · 10 homework #3....

Year 12 Chemistry Spring Term Homework Pack

Name: _________________________

Class: _________________________

Teacher: _________________________

Our Spring Term Homework Programme.

Due on [Friday]:

Approximate

Time

Needed

Is there help?

Where can I find it?

Week

#1

Homework 1: [10th Jan]

30 minutes Goo.gl/N1NpEc

Week

#2



Week

#3



Week

#4

Homework 4: [31st Jan]


Week

#5

Homework 5: [7th Feb]


Week

#6



Week

#7 -

Half

Term



Week

#8

Homework 8: [6th Mar]


Week

#9



Week

#10



Week

# 11



Week

#12

Homework 12: [4th Apr]


2

Homework #1. DUE: [10th Jan]

[Title]

2.5 EXERCISE 1 – reactions of the halogens and halide ions

1. Describe and explain the how the following properties of the halogens change as you descend group

VII:

a) boiling point

b) electronegativity

c) oxidising power

2. Describe what you see if you combined the following reagents, and write equations for any reactions

that take place:

a) chlorine with aqueous sodium bromide

b) chlorine with aqueous sodium iodide

c) bromine with aqueous sodium chloride

d) bromine with aqueous sodium iodide

e) iodine with aqueous sodium chloride

f) iodine with aqueous sodium bromide

3. a) Write half-equations to show the following processes:

i) The reduction of H2SO4 to SO2

ii) The reduction of H2SO4 to H2S

iii) The oxidation of Br- to Br2

iv) The oxidation of I- to I2

3

b) Write equations to show the following processes:

i) The reduction of H2SO4 to SO2 by bromide ions

ii) The reduction of H2SO4 to H2S by iodide ions

iii) The reaction between H2SO4 and chloride ions

c) Explain what you would observe in the reactions in (b).

d) Explain what these reactions tell you about the reducing power of the halides.

4. Explain how you would distinguish between solutions containing chloride, bromide and iodide ions.

Describe a further test to support your conclusion.

5. Write equations for the reactions of chlorine with water and cold dilute sodium hydroxide solution.

Give a use for each reaction.

6. Based on their position in the Periodic Table, suggest what would happen when:

a) fluorine was bubbled through sodium astatide solution

b) astatine was mixed with sodium fluoride solution

c) silver astatide was dissolved in concentrated ammonia

d) sodium fluoride was reacted with concentrated sulphuric acid

e) sodium astatide was reacted with concentrated sulphuric acid

4

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5


[Title]

Topic 6 Exercise 2 – Group II Chemistry

1. By what name are the group II metals also known?

2. State and explain the trend in atomic radius down group II

3. State and explain the trend in first ionization energy down group II

4. State and explain the trend in melting point down group II

5. a) State and explain how the reactivity of the group II elements to water

changes down the group.

b) Write equations for:

i) the reaction of magnesium with steam

ii) the reaction of calcium with water

iii) the reaction of barium with water

c) State two differences you would observe in the reactions of calcium and

barium with water.

7

6. a) State the trend in the solubility of the Group II sulphates

b) State the trend in the solubility of the Group II hyrdoxides

c) Hence state what you would observe when the following solutions are mixed, and write ionic equations for any reactions you observe:

i) barium chloride and sulphuric acid

ii) barium chloride and sodium hydroxide

iii) magnesium chloride and sodium hydroxide

iv) calcium chloride and sodium hydroxide

v) calcium chloride and sulphuric acid

vi) magnesium chloride and sulphuric acid

d) Hence describe a suitable test for sulphate ions in solution

e) Hence explain how BaSO4 is used in medicine

f) Hence explain how MgSO4 is used in medicine

8

7. Write equations for the following reactions:

a) magnesium hydroxide with hydrochloric acid

b) calcium hydroxide with hydrochloric acid

c) calcium oxide with sulphur dioxide

d) calcium carbonate with sulphur dioxide

8. Explain a useful application of each of the reactions in question 7.

Content Opportunities for skills development

9. Explain the use of magnesium in the extraction of titanium from TiCl4

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[Title]

2.1 EXERCISE 1 – measuring enthalpy changes

In all the following questions, assume that the densities and specific heat capacities of the

solutions are the same as pure water

i.e. ρ = 1.0 gcm-3 and c = 4.18 Jg-1K-1

1. Zinc will displace copper from copper (II) sulphate solution according to the following equation:

CuSO4(aq) + Zn(s) → Cu(s) + ZnSO4(aq)

If an excess of zinc powder is added to 50 cm3 of 1.0 moldm-3 copper(II) sulphate, the

temperature increases by 6.3 oC. Calculate the enthalpy change for the reaction.

2. Magnesium will also displace copper from copper (II) sulphate solution. If an excess of

magnesium is added to 100 cm3 of 1.0 moldm-3 copper(II) sulphate, the temperature increases

by 46.3 oC.

a) Calculate the molar enthalpy change for the reaction

b) Calculate the minimum quantity of magnesium required to ensure it is in excess.

c) Calculate the temperature change if only 0.8 g of magnesium is added.

3. When 5.73 g of sodium chloride (NaCl) dissolves in 100 cm3 of water, the temperature of the

water fell from 22.4 oC to 19.8 oC. Calculate the enthalpy change of the reaction.

4. When 2.3 g of magnesium chloride dissolves in 200 cm3 of water, the temperature rose by 3.4 oC. Calculate the enthalpy change for the reaction.

5. If 50 cm3 of 0.1 moldm-3 HCl and 50 cm3 of 0.1 moldm-3 NaOH are mixed, the temperature of

the solution rises by 0.68 oC. Calculate the enthalpy change of the reaction in kJmol-1.

11

6. If 50 cm3 of 1.0 moldm-3 NaOH is added to 25 cm3 of 2.0 moldm-3 CH3COOH, the temperature

rose by 8.3 oC. Calculate the molar enthalpy change for the reaction.

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13

Homework #4. DUE: [31st Jan]

[Title]

2.1 EXERCISE 2 - bond dissociation enthalpies

1. Given the following data:

bond Hb/kJmol-1 bond Hb/kJmol-1

C-H +413 H-F +565

C-Br +280 C-F +425

H-Br +366 F-F +158

Br-Br +193 C=O +805

C-C +347 O-H +464

C=C +611 O=O +498

H-H +435

Substance Hat/kJmol-1

C(graphite) +713

Calculate:

a) The H for the following reaction: CH4(g) + Br2(g) → CH3Br(g) + HBr(g)

b) The H for the following reaction: CH4(g) + F2(g) → CH3F(g) + HF(g) c) The enthalpy of formation of HF d) The enthalpy of formation of propene e) The enthalpy of formation of 1,2-dibromopropane f) The enthalpy of formation of methane g) The enthalpy of formation of ethane h) The enthalpy of combustion of ethane

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2. The enthalpy of formation of ammonia is -46 kJmol-1 and the bond dissociation enthalpies of nitrogen gas and hydrogen gas are +945 kJmol-1 and +436 kJmol-1 respectively. Calculate the average bond enthalpy of an N-H bond.

3. Given the following information:

C(s) → C(g), H = +715 kJmol-1

Cl2(g) → 2Cl(g), H = +242 kJmol-1

C(s) + 2Cl2(g) → CCl4(g), H = -135.5 kJmol-1

Calculate the average bond dissociation enthalpy of a C-Cl bond.

4. Given that the enthalpy of formation of 1-iodobutane is -52.0 kJmol-1 and that the bond

dissociation enthalpy of I-I is +214 kJmol-1, use the data at the top of the page to calculate

the bond dissociation enthalpy of the C-I bond. The structure of 1-iodobutane is shown

below:

15

C C C C

H H H H

H

H H H H

I

5. Given that the enthalpy of formation of ethanol is -277 kJmol-1, use the data at the top of

the page to calculate the bond dissociation enthalpy of the C-O bond.

16

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17

Homework #5. DUE: [7th Feb]

[Title]

2.1 EXERCISE 3 - Hess' Law

Using standard enthalpies of formation


Substance H2O(l) CO2(g) Ethane C2H6(g) Ethene C2H4(g)

Hf/kJmol-1 -285.5 -393 -83.6 +52.0

a) Write equations for the complete combustion of

i) ethane

ii) ethene

iii) hydrogen

b) Calculate the enthalpy of combustion in each case using the above data.

2. Given the following data: Hf(CH4) = -74.8 kJmol-1, Hf(CH3Cl) = -134.5 kJmol-1, Hf(HCl) = -

92.3 kJmol-1;

Calculate H for the reaction CH4(g) + Cl2(g) → CH3Cl(g) + HCl(g)

3. Given the data:

4NH3(g) + 3O2(g) → 2N2(g) + 6H2O(l), H = -1530kJmol-1

H2(g) + 1/2O2(g) → H2O(l), H = -288 kJmol-1

Calculate the enthalpy of formation of ammonia.

4. Given the data:

Substance B2H6(g) B2O3(s) C6H6(g) CO2(g) H2O(g)

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Hf/kJmol-1 +31.4 -1270 +83.9 -393 -242

Calculate the enthalpy of combustion of gaseous diborane and gaseous benzene given that they burn

according to the following equations:

B2H6(g) + 3O2(g) → B2O3(s) + 3H2O(g), C6H6(g) + 7.5O2(g) → 6CO2(g) + 3H2O(g)

5. When ethanol burns in oxygen under standard conditions, carbon dioxide, water and 1368 kJmol-

1 of energy are produced. Calculate the enthalpy of formation of ethanol, given that the enthalpies

of formation of carbon dioxide and water are -393.7 and -285.9 kJmol-1 respectively.

19

Using standard enthalpies of combustion

6. Calculate the enthalpy of formation of butane (C4H10) from the following data:

Enthalpy of combustion of graphite = -393.6 kJmol-1

Enthalpy of combustion of hydrogen = -285.9 kJmol-1

Enthalpy of combustion of butane = -2877.1 kJmol-1


Substance CH3CH2CH2CH3 CH3CH2CH=CH2 H2

Hc/kJmol-1 -2877 -2717 -286

Calculate H for the following reaction: CH3CH2CH=CH2 + H2 → CH3CH2CH2CH3


CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) H = -890 kJmol-1

CO(g) + 1/2O2(g) → CO2(g) H = -284 kJmol-1

C(s) + O2(g) → CO2(g) H = -393 kJmol-1

H2(g) + 1/2O2(g) → H2O(l) H = -286 kJmol-1

Calculate:

a) The enthalpy of formation of methane

b) The enthalpy of formation of carbon monoxide

c) The enthalpy change when methane is burned in limited oxygen to form carbon monoxide and

water.

20

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[Title]

TOPIC 7 EXERCISE 1 - Representation and formulae of organic compounds

1. Given two molecular formulae C4H10 and C4H8;

Select a compound which could be:

a) an alkane

b) a cycloalkane

c) an alkene

In each case, draw one possible structure to show how your choice is correct.

2. State the class of organic molecule to which the following compounds belong:

a) CH3CH2CH3 b) CH3CH=CH2 c) CH3CH2CH2Br

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[Title]

1.5 EXERCISE 2 - Nomenclature of organic compounds

1. Name the following compounds:

a) b)

CH3

CH3

H C

H

H

C

H

H

HCC

H

H

C C

H

H

H

H

C

H

H

CBr

H

c) d)

C C C

H

H

HHH

H

C

H

H

C

H

H

CC

H

H

H

Cl HC

H

H

C

HHH

e) CH3CH(CH3)CH3 f) CH3CHBrCH2Br g) CH2=CHCH2CH3

h) CH3CH=C(CH3)CH3

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2. Draw the structures of the following compounds:

a) methylbutane b) cyclohexane c) but-1-ene

d) 3-ethyl,2-methylhex-1-ene e) 3-chlorobut-1-ene

f) 1,1-dichloropropane g) 2,2,4-trimethylheptane h) pent-2-ene

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Homework #8. DUE: [6th Mar]

[Title]

1.6 Exercise 1 – Fractional Distillation, Cracking and Combustion

1. Petroleum is separated into its fractions by fractional distillation

a) What are fractions?

b) Explain how a fractionating column works in five key points.

c) Write a list of the fractions, in order of increasing boiling point, and give a use for each.

d) Why is fractional distillation important?

2. Many of the fractions are then subjected to a process called cracking.

a) Name the two types of cracking. State the conditions required for each and give one useful

product of each process.

b) Why is cracking economically important?

3. Most of the fractions produced during fractional distillation are used as fuels.

a) Write an equation for the complete combustion of octane.

b) Write two equations for the incomplete combustion of octane.

c) Give two reasons why incomplete combustion is undesirable.

4. a) Identify five pollutants produced during the combustion of alkanes.

b) Explain why each is harmful.

c) Explain how two of these pollutants are removed from exhaust fumes. Write an equation to

illustrate your answer.

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[Title]

2.8 EXERCISE 1 – CHLORINATION OF ALKANES

1. Alkanes react with halogens in a reaction described as homolytic free radical substitution. Explain

what is meant by the terms:

i) homolytic ii) free radical iii) substitution

2. a) Using full displayed formulae, show the four steps involved in the reaction of ethane with

chlorine to give chloroethane. State the type of reaction involved in each step.

b) Show by mans of additional steps how this mechanism can account for the formation of:

iv) 1,1-dichloroethane v) butane

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[Title]

2.8 EXERCISE 2 – reactions of haloalkanes

1. a) Draw the structure of a chlorofluorocarbon and write an equation to show

how it can release chlorine radicals in the presence of ultra-violet light.

b) Write equations to show how chlorine radicals can catalyse the destruction of ozone.

2. a) Explain why haloalkanes can react with nucleophiles.

b) Write an equation and give the mechanism for the following reactions:

i) bromoethane with aqueous sodium hydroxide

ii) 2-chloropropane with potassium cyanide

iii) 1-iodobutane with ammonia

3. State two types of reaction that could take place when 1-chlorobutane reacts with potassium

hydroxide. Give the mechanism for each reaction and state the role of the hydroxide ion in each

case. Suggest conditions which would favour each type of reaction.

4. Suggest, giving reasons, which of chloroethane, bromoethane and iodoethane will react fastest with

sodium hydroxide.

5. State the possible products that could be formed when the following haloalkanes undergo

elimination. If more than one product is formed, identify them both and explain how each is formed.

a) 1-bromobutane

31

b) 2-bromobutane

c) 1-bromomethylpropane

d) 2-bromomethylpropane

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[Title]

2.9 EXERCISE 1 – E-Z STEREOISOMERISM

1. Draw the four isomers of C4H8 containing a C=C bond and name them. State whether the

compounds are structural or geometrical isomers of each other.

2. Identify which of the following molecules display E-Z stereoisomerism and, if they do, draw

and name the two isomers:

a) pent-1-ene

b) pent-2-ene

c) 2-methylbut-1-ene

d) hex-3-ene

e) 2-ethylbut-1-ene

f) 3,3-dimethylbut-1-enene

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Homework #12. DUE: [4th Apr]

[Title]

2.9 EXERCISE 2 – addition reactions of alkenes

1. Write equations, using displayed formulae, to show the conversion of but-1-ene into:

a) polybut-1-ene

b) butan-2-ol

c) 2-bromobutane

d) 1,2-dibromobutane

2. a) Explain why alkenes tend to react with electrophiles.

b) Show the mechanisms for the following reactions:

i) ethene with bromine

ii) but-2-ene with hydrogen bromide

iii) ethene with concentrated sulphuric acid

c) Explain how bromine can behave as an electrophile.

3. The following reactions give two products in unequal amounts. In each case, identify the two

products, state which is the major product, explain why it is the major product and give the

mechanism for its formation.

a) but-1-ene with HBr

b) methylpropene with concentrated sulphuric acid

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year 12 chemistry spring term homework pack name: science... · 2020. 3. 16. · 10 homework #3....

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