O LEVEL PAST PAER QUESTIONS.______________________________________________________________________________TOPIC 2: Experimental Techniques

1- A gas Y, is less dense than air, very soluble in water and is an alkali.Which method is used to collect a dry sample of the gas? C[J03/Q2]2- What is the most suitable way of investigating the different food colourings in some drinks?A- crystallisation B- filtration C- fractional distillation D- paper chromatography[DO3/Q1] 3- Potassium nitrate crystals can be separated from sand using the four processes shown below. Which of the following shows the processes in the correct order. First lastABCDfilter dissolvedissolvedissolvedissolveevaporateevaporatefilterevaporatecrystallinefilterevaporatecrystallinefiltercrystallinecrystalline

[D01/Q3]4-The equation for the reaction between aqueous lead( II) nitrate and aqueous potassium iodide is shown.

Which method could be used to separate the products?A chromatographyB crystallisationC distillationD filtration [JO3/Q1]5- The diagram shows the chromatogram of four different sugars using the same solvent.Glucose has an Rf value of 0.5.Which sugar is glucose? C[DO4/Q2]

6- The diagram shows apparatus used to separate hexane (boiling point, 70 oC) and heptane(boiling point, 98 oC).

Which graph would be obtained if the temperature at point T was plotted against the total volumeof distillate collected? A

[DO4/Q4]7- Substance X melts at 53 oC and boils at 100 oC. It does not dissolve in water and it does not reactwith water.Which diagram shows the method most suitable for separating X from a mixture of X and water? C

[NO5/Q2]8- Which test could be used to show that a sample of water is pure?A It freezes at exactly 0 oC.B It turns anhydrous copper(II) sulphate blue.C It turns cobalt(II) chloride paper pink.D When it evaporates, it leaves no residue. [JO6/Q4]9- An aqueous solution of compound X reacts with aqueous sodium hydroxide to form a greenprecipitate and then aluminium powder is added. The mixture is heated and a gas that turnsdamp red litmus paper blue is given off.What is X?A ammonium nitrateB copper(II) chlorideC iron(II) nitrateD iron(III) chloride [NOV -2006/Q3]

10- Which of the following reagents could be used to distinguish between dilute nitric acid and dilutehydrochloric acid?A aqueous barium chlorideB copper(II) carbonateC aqueous silver nitrateD aqueous sodium hydroxide [NOV -2006/Q4] 11- The scheme shows some reactions of a compound Y.What could the compound Y be?A aluminium sulphateB calcium carbonateC copper(II) carbonateD zinc carbonate [NOV -2006/Q5]

12- A mixture of two substances is spotted on to a piece of chromatography paper.The paper is inserted into a beaker containing a liquid.

For separation of the substances to occur the mixture mustA be placed so that the spot is just below the level of the liquid.B be soluble in the liquid.C contain substances of the same Rf values.D contain substances that are coloured. [J07/Q2]13- Which pair of substances are both mixtures?A air; waterB limewater; waterC sea-water; airD sea-water; ethanol [J07/Q3]14-The diagram shows a simple laboratory apparatus for the preparation and collection of a dry gas.What is the gas?A carbon dioxideB chlorineC hydrogenD hydrogen chloride [J07/Q4][J10/Q1]15- Which gas burns in air to form a single product?A ammoniaB carbon monoxideC hydrogen chloride D methane [J07/Q34]16- Oxygen was prepared from hydrogen peroxide and collected as shown in the diagram. The first few tubes of gas were rejected because the gas was contaminated by A water vapour. B hydrogen peroxide. C hydrogen. D nitrogen.

[J08/Q1]17- The diagram shows the chromatogram obtained by analysis of a single dye.Three measurements are shown. B

[J08/Q7]18- Which method could be used to obtain charcoal from a mixture of powdered charcoal with sodiumchloride?A chromatographyB filtration after shaking with waterC heating the mixtureD distillation [N08/Q2]19- The diagram shows a chromatogram of several inks.

Which statement is correct?A Black ink can be made by mixing green, red and yellow inks.B Brown ink can be made by mixing blue and red inks.C Yellow ink can be used to make brown ink.D Yellow ink may be present in green ink. [J09/Q2]20- The oxidation of ethanol to ethanoic acid is often carried out in the apparatus shown. What is the purpose of the condenser? A to prevent air reacting with the ethanoic acid B to prevent any ethanol from escaping C to prevent the ethanoic acid changing back to ethanol D to prevent the ethanoic acid reacting with the ethanol [J09/Q3]

21- The diagram shows a simple laboratory apparatus for the preparation and collection of a dry gas. What is the gas? A carbon dioxide B chlorine C hydrogen D hydrogen chloride

22- A mixture containing equal volumes of two liquids that mix completely but do not react together isplaced in the apparatus shown and heated until the thermometer first shows a steady reading.At which position will there be the highest proportion of the liquid with the higher boiling point? D

23- The two statements are about the fractional distillation of crude oil. The statements may or maynot be correct. They may or may not be linked.statement 1 Fractional distillation is used to separate crude oil into useful fractions.statement 2 The fractions with lower boiling points are found at the top of the fractionatingcolumn.What is correct about these two statements?A Both statements are correct and statement 2 explains statement 1.B Both statements are correct but statement 2 does not explain statement 1.C Statement 1 is correct but statement 2 is incorrect.D Statement 1 is incorrect but statement 2 is correct. [J10/Q34]24- The boiling points of various gases found in the air are shown below. B

If the air is cooled, the first substance to condense is water.If the temperature is lowered further, what is the next substance to condense?A argonB carbon dioxideC nitrogenD oxygen [N10/Q1]25- The fractional distillation apparatus shown is to be used for separating a mixture of two colourlessliquids. A thermometer is missing from the apparatus.Where should the bulb of the thermometer be placed? B [N10/Q3]

26- Copper(II) sulfate crystals are separated from sand using the four processes listed below.In which order are these processes used? D[J11/Q2]

27- The labels fell off two bottles each containing a colourless solution, one of which was sodiumcarbonate solution and the other was sodium chloride solution.The addition of which solution to a sample from each bottle would most readily enable the bottlesto be correctly relabelled?A ammoniaB hydrochloric acidC lead(II) nitrateD sodium hydroxide [N11/Q2]28- In a titration between an acid (in the burette) and an alkali, you may need to re-use the sametitration flask.Which is the best procedure for rinsing the flask?A Rinse with distilled water and then with the alkali.B Rinse with tap water and then with distilled water.C Rinse with tap water and then with the acid.D Rinse with the alkali. [N11/Q3]29- When dilute hydrochloric acid is added to a white powder a gas is produced.The solution remaining is tested separately with small volumes of both aqueous ammonia andaqueous sodium hydroxide.A white precipitate is produced in both tests.What is the white powder?A aluminium oxideB calcium oxideC copper(II) carbonateD zinc carbonate [J12/Q3]30- A mixture of two substances is spotted onto a piece of chromatography paper.The paper is inserted into a beaker containing a liquid. [J12/Q4]

For separation of the substances to occur the spot of mixture mustA be placed so that the spot is just below the level of the liquid.B be soluble in the liquid.C contain substances of the same Rf values.D contain substances that are coloured. [J12/Q4]31- Which reagent could be used to distinguish between dilute nitric acid and dilute hydrochloricacid?A aqueous barium chlorideB aqueous silver nitrateC aqueous sodium hydroxideD copper(II) carbonate [J12/Q4]32- When the rubber bulb of the dropper in the diagram is squeezed, the aqueous silver nitrate dropsinto the aqueous sodium chloride and a white precipitate of silver chloride is formed. What happens to the total mass of the bottle and contents? A It increases due to the formation of the heavy precipitate. B It remains the same because only a physical change has taken place. C It decreases because heat is evolved. D It remains the same because none of the products escapes from the bottle. [J12/Q12]

33- Which ion reacts with aqueous ammonia to give a precipitate that dissolves in an excess ofammonia?A Al3+(aq) B Fe2+(aq) C Fe3+(aq) D Zn2+(aq) [J12/Q19]34- Which process would destroy the bacteria in water?A chlorinationB desalinationC filtrationD treatment with carbon [J12/Q34]35- Which is a property of hydrogen gas?A It burns in air.B It has an unpleasant smell.C It relights a glowing splint.D It turns moist litmus paper red. [N12/Q1]36- Hydrogen chloride is very soluble in water, whereas chlorine is only slightly soluble in water.Both gases can be dried using concentrated sulfuric acid.Which diagram represents the correct method of obtaining pure dry chlorine from damp chlorinecontaining a small amount of hydrogen chloride? B [N12/Q3]

37- A

38- Which mixture could best be separated by using a separating funnel?A oil and sandB oil and waterC sodium chloride and sandD sodium chloride and water [June 2013/1]39- Which process involves boiling a liquid and condensing the vapour?A crystallisationB distillationC evaporationD filtration [June 2013/1]40- The diagram shows the fractionation of crude oil.Which statement is correct?A Each fraction consists of a single compound.B Fraction P has the highest boiling point.C The highest temperature is at the top of the column.D The naphtha fraction is used as feedstock for the chemical industry. [Nov 2013/3]

41- The apparatus shown is used to distil a dilute solution of ethanol in water.[B.P.: ethanol, 78 C; water 100 C]

Which graph shows the change in concentration of the ethanol in the boiling flask as thedistillation proceeds? C

Paper -2 1- Sorrel is a small green plant.(a) The pigments in the sorrel leaf can be separated by chromatography.

(i) Describe how chromatography can be used to separate different pigments. [2]

(ii) Explain what is meant by Rf value. [1]

(b) Sorrel plants contain a poisonous carboxylic acid X.What can be deduced about X from each of the following three pieces of information?(i) When X is warmed with acidified potassium manganate(VII), the solution changes frompink to colourless. [1]

(ii) Aqueous bromine is not decolourised when added to a solution of X. [1]

(iii) A 0.1 mol/dm3 solution of X has a pH of 3 whereas a 0.1 mol/dm3 solution of hydrochloric

acid has a pH of 1. [1](c) Analysis of 10.0 g of carboxylic acid X shows that it contains 2.67 g carbon, 0.220 g hydrogen and 7.11 g oxygen.

(i) Deduce the empirical formula of X. [3]

(ii) The relative molecular mass of X is 90. Deduce the molecular formula of X. [1]

[Total: 10]2- Barium is a reactive metal in Group II of the Periodic Table.Barium reacts with water in a similar way to sodium. The products of the reaction are aqueousbarium hydroxide and a colourless gas.(a) Barium sulfate is an insoluble compound.Describe how a pure dry sample of barium sulfate is prepared from aqueous bariumnitrate..........................................................................................................................................................

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...............................................................................................................................................................................................................................................................................................................[4]3- Small pieces of a silver coloured metal, X, were added to concentrated nitric acid. A browngas, Z, and a colourless solution containing salt Y were formed.Analysis of a 0.0914 mol sample of Z showed it contained 1.28 g of nitrogen and 2.93 g ofoxygen.The small sample of the colourless solution was diluted with water and then divided into twoportions. To one portion, aqueous sodium hydroxide was added drop by drop until it was inexcess. A white precipitate, W, was formed that redissolved in the excess sodiumhydroxide. To the other portion, aqueous ammonia was added drop by drop until it was inexcess. A white precipitate, W, was formed that redissolved in the excess ammonia.(a) (i) Name the white precipitate, W.

............................................................................................................................. [1](ii) Construct the ionic equation, with state symbols, for the formation of W.

............................................................................................................................. [2](b) Name X and Y.X is .................................................................................................................................................

Y is ..............................................................................................................................................[2](c) (i) Calculate the relative formula mass, Mr, for gas Z. Mr = ................................................. [2](ii) Determine the molecular formula for Z.

molecular formula..[2][Total : 9]Many fertilisers contain phosphate ions and nitrate ions.(a) Explain why farmers put fertilisers on the soil.

.....................................................................................................................................................[1](b) Why should the chemicals in fertilisers be soluble in water?.....................................................................................................................................................[1](c) Ammonium nitrate, NH4NO3, and ammonium sulfate, (NH4)2SO4, are commonly used infertilisers.(i) Calculate the percentage of nitrogen by mass in ammonium nitrate.

[3](ii) Describe how crystals of ammonium sulfate can be prepared from aqueousammonia..........................................................................................................................................................

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..............................................................................................................................[4](d) The formula of calcium phosphate is Ca3(PO4)2.Use this formula to deduce the charge on the phosphate ion.

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