Separation and purification

Which technique is used to separate a mixture of sugar and glass?

Feb/March 2016

The diagram illustrates a method of cleaning muddy water. Which purification process is being shown?

Feb/March 2017

The diagram illustrates how muddy water can be purified. Which purification process is shown for the muddy water?

Feb/March 2017

Which two gases are separated from liquid air by fractional distillation?

Feb/March 2017

Silver dichromate, $\text{Ag}_2\text{Cr}_2\text{O}_7$, is a red insoluble salt. It may be prepared by adding silver nitrate solution to ammonium dichromate solution. The reaction is represented by the equation shown below. $2\text{AgNO}_3(aq) + (\text{NH}_4)_2\text{Cr}_2\text{O}_7(aq) \rightarrow 2\text{NH}_4\text{NO}_3(aq) + \text{Ag}_2\text{Cr}_2\text{O}_7(s)$

Feb/March 2017

A student is provided with a mixture containing barium sulfate, copper(II) sulfate and water. The table gives details about barium sulfate and copper(II) sulfate. How does the student obtain copper(II) sulfate crystals from the mixture?

Feb/March 2018

Air consists of a mixture of gases. The melting and boiling points of several gases found in clean, dry air are given. During the fractional distillation of liquid air, which gas is the first to boil?

Feb/March 2018

Copper(II) sulfate crystals have a blue colour. They are prepared by first adding copper(II) oxide in excess to sulfuric acid. The mixture is then heated and stirred. After this, it is filtered and the filtrate is left to evaporate, producing blue crystals. Why is filtration necessary?

Feb/March 2019

What method is used to separate a mixture of two liquids?

Feb/March 2019

The fractional distillation of petroleum is illustrated. Which fraction is the least volatile?

Feb/March 2019

Lead(II) iodide does not dissolve in water. Lead(II) iodide is prepared by mixing aqueous lead(II) nitrate with aqueous potassium iodide. Which pieces of apparatus are required to isolate solid lead(II) iodide from $20\,\text{cm}^3$ of aqueous lead(II) nitrate?

Feb/March 2019

What separation method should be used to separate a mixture of two liquids?

Feb/March 2019

Lead(II) iodide does not dissolve in water. It is produced by adding aqueous lead(II) nitrate to aqueous potassium iodide. Which apparatus is required to separate and collect solid lead(II) iodide from $20\,\text{cm}^3$ of aqueous lead(II) nitrate?

Feb/March 2019

Which are the principal substances obtained from the fractional distillation of liquid air?

Feb/March 2019

A diagram of the fractional distillation of petroleum is shown. Which fraction is the least volatile?

Feb/March 2019

Petroleum is a crucial raw material that can be split into useful products. Which terms are used to describe petroleum and the method used to separate it?

Feb/March 2020

Petroleum is an important raw material that can be separated into useful products. Which terms are used to describe petroleum and the method used to separate it?

Feb/March 2020

The apparatus for separating a mixture of sand, methanol and ethanol is shown. Which row correctly names the labels on the diagrams?

Feb/March 2021

A mixture consists of sand and an aqueous solution of sodium chloride. Which processes would be used to separate out a sample of solid sand and a sample of solid sodium chloride from this mixture?

Feb/March 2023

A mixture consists of sand and an aqueous solution of sodium chloride. Which processes are used to obtain a sample of solid sand and a sample of solid sodium chloride from the mixture?

Feb/March 2023

Why is distilled water used for chemical experiments instead of tap water?

Feb/March 2024

Two experiments are given below. experiment 1: A large amount of copper(II) sulfate is stirred into a beaker containing water. After a few minutes, crystals that have not dissolved can be seen at the bottom of the beaker. experiment 2: Sea water is distilled. Distilled water and solid impure salt are collected separately in two containers. Which statement is correct?

Feb/March 2024

Solid magnesium carbonate, which is insoluble, is made to react with dilute sulfuric acid. magnesium carbonate + sulfuric acid $\rightarrow$ magnesium sulfate + water + carbon dioxide The procedure for producing crystals of magnesium sulfate is given below. step 1 Place excess magnesium carbonate into dilute sulfuric acid and stir the mixture. step 2 Filter off the mixture. step 3 Heat the filtrate until the crystallisation point is reached. step 4 Allow the filtrate to cool down. Which solid is left behind as the residue removed from the mixture in step 2?

Feb/March 2025

Lead(II) sulfate is an insoluble salt. Which method would be suitable for obtaining pure lead(II) sulfate in solid form?

Feb/March 2025

The diagram illustrates how petroleum is separated into fractions. What might X, Y and Z stand for?

May/June 2016

The diagram illustrates how petroleum is separated into fractions. What might X, Y and Z be?

May/June 2016

Barium sulfate is an insoluble salt. It may be prepared by mixing copper(II) sulfate solution with barium nitrate solution. $\text{CuSO}_4(aq) + \text{Ba(NO}_3)_2(aq) \rightarrow \text{Cu(NO}_3)_2(aq) + \text{BaSO}_4(s)$ What is the correct sequence of stages to obtain a pure, dry sample of barium sulfate from the reaction mixture?

May/June 2016

The industrial fractional distillation of petroleum is illustrated. Which process occurs at Y?

May/June 2017

The table gives the solubility of four substances W, X, Y and Z in ethanol and in water. Two separation methods are listed below. • method 1: put the substance into ethanol and then filter • method 2: put the substance into water and then filter Which substances may be separated from one another using both method 1 and method 2?

May/June 2017

What process is used to produce a more concentrated solution of ethanol from a dilute solution of ethanol in water?

May/June 2017

Silver chloride is a white solid that is insoluble in water. Which statement explains how a pure sample of silver chloride may be prepared?

May/June 2017

The industrial fractional distillation of petroleum is illustrated. Which process takes place at Y?

May/June 2017

Silver nitrate reacts with sodium chloride to form silver chloride and sodium nitrate. The reaction equation is shown below. $\text{AgNO}_3(\text{aq}) + \text{NaCl}(\text{aq}) \rightarrow \text{AgCl}(\text{s}) + \text{NaNO}_3(\text{aq})$ By what method is silver chloride separated from the mixture of products?

May/June 2017

Fuel oil, gasoline, kerosene and naphtha are four fractions separated by the fractional distillation of petroleum. In what order do their boiling points increase?

May/June 2017

State the name of the process used to obtain oxygen from liquid air.

May/June 2017

Barium carbonate, $\text{BaCO}_3$, is a solid that is insoluble.

May/June 2017

Substances may be grouped as elements, compounds, or mixtures.

May/June 2018

State the name of the process that is used to obtain water from aqueous sodium chloride.

May/June 2018

Rock salt contains sand mixed with sodium chloride. Sodium chloride dissolves in water, but it does not dissolve in hexane. Sand does not dissolve in either water or hexane. What is needed to remove the sand from the sodium chloride?

May/June 2019

An acid is neutralised by adding an excess of an insoluble solid base. A soluble salt is formed. How is the pure salt recovered from the reaction mixture?

May/June 2019

Which procedure is used to separate a soluble salt from a mixture containing a soluble salt and an insoluble salt?

May/June 2019

In water, calcium carbonate is insoluble, but sodium chloride is soluble. What sequence of steps would you use to isolate a pure, dry sample of calcium carbonate from a mixture containing calcium carbonate and aqueous sodium chloride?

May/June 2019

Copper(II) sulfate is made by reacting excess copper(II) oxide with warm dilute sulfuric acid. Which purification method is used to obtain pure solid copper(II) sulfate from the reaction mixture?

May/June 2021

A mixture is being separated using the apparatus illustrated. Which mixture is it?

May/June 2021

Some sugar has become mixed with glass. How can a sample of the sugar in solid form be removed from the mixture?

May/June 2021

Copper(II) sulfate is made by adding excess copper(II) oxide to warm dilute sulfuric acid. Which purification methods are needed to obtain pure solid copper(II) sulfate from the reaction mixture?

May/June 2021

The apparatus illustrated is used to separate a mixture. What mixture is it?

May/June 2021

When aqueous sodium sulfate and barium chloride solutions are combined. $\text{Na}_2\text{SO}_4(\text{aq}) + \text{BaCl}_2(\text{aq}) \rightarrow \text{BaSO}_4(\text{s}) + 2\text{NaCl}(\text{aq})$ What process is used to collect a sample of barium sulfate from the reaction mixture?

May/June 2021

What is the name of the process used to make ammonia from nitrogen?

May/June 2021

State the name of the process used to make large molecules from monomers.

May/June 2021

An acid is neutralised by adding an excess of an insoluble solid base. A soluble salt is produced. How can the pure salt be obtained from the reaction mixture?

May/June 2022

What separation method would be suitable for a mixture of these liquids? Methanol (boiling point $64.5\,^{\circ}\text{C}$) Ethanol (boiling point $78.5\,^{\circ}\text{C}$) Propan-1-ol (boiling point $97.2\,^{\circ}\text{C}$) Butan-1-ol (boiling point $117.0\,^{\circ}\text{C}$)

May/June 2022

Which substance needs to be pure for its intended use?

May/June 2022

If an acid is neutralised by adding extra insoluble solid base, a soluble salt is produced. How is the pure salt separated from the reaction mixture?

May/June 2022

What method is used to separate a mixture of the liquids below?

May/June 2022

The acid is neutralised by the addition of an excess amount of an insoluble solid base. A soluble salt is produced. How is the pure salt isolated from the reaction mixture?

May/June 2022

What method is used to separate a mixture containing the following liquids? methanol (boiling point $64.5\,^{\circ}\text{C}$) ethanol (boiling point $78.5\,^{\circ}\text{C}$) propan-1-ol (boiling point $97.2\,^{\circ}\text{C}$) butan-1-ol (boiling point $117.0\,^{\circ}\text{C}$)

May/June 2022

An acid is neutralised by using an excess of an insoluble solid base. A soluble salt is produced. How is the pure salt separated from the reaction mixture?

May/June 2022

For the intended use, which substance needs to be pure?

May/June 2022

An acid is neutralised by the addition of an excess of an insoluble solid base. A soluble salt is produced. How is the pure salt separated from the reaction mixture?

May/June 2022

An acid is neutralised by the addition of an excess of an insoluble solid base. A soluble salt is produced. How can the pure salt be separated from the reaction mixture?

May/June 2022

Rock salt contains salt and sand mixed together. The separation procedure for removing the sand from the salt is shown below. step 1 Break up the rock salt, add warm water, and stir. step 2 Pass the mixture through filter paper in a funnel. step 3 Remove the water by evaporation to form salt crystals. Which statement about this procedure is correct?

May/June 2023

A fractionating column separates the hydrocarbon fractions in petroleum using fractional distillation. Which row gives the properties of the fractions that condense at the top of the fractionating column?

May/June 2023

Copper(II) carbonate is produced when aqueous sodium carbonate is mixed with aqueous copper(II) nitrate. The ionic equation for the reaction is given as: $\text{CO}_3^{2-}(aq) + \text{Cu}^{2+}(aq) \rightarrow \text{CuCO}_3(s)$. How can pure copper(II) carbonate be separated from the reaction mixture?

May/June 2023

Rock salt contains a mixture of salt and sand. The procedure for separating the sand from the salt is given below. step 1 Break up the rock salt, add warm water and stir it. step 2 Pour the mixture through filter paper placed in a funnel. step 3 Let the water evaporate so that the salt crystallises. Which statement about the procedure is correct?

May/June 2023

Copper does not dissolve in water. Copper(II) oxide is a solid that will not dissolve in water, but it does react with dilute hydrochloric acid. Which method is used to separate copper from a mixture containing copper and copper(II) oxide?

May/June 2024

What substances may be used to produce pure crystals of sodium sulfate?

May/June 2024

Petroleum is a mixture. Which method is used to separate petroleum into its constituent substances?

May/June 2024

Dissolved sodium chloride is present in sea water. Which method is used to obtain pure water from it?

May/June 2024

Which row shows methods used to test the purity of a compound?

May/June 2024

Lead(II) iodide is produced as a precipitate in the reaction shown below. $\text{Pb(NO}_3)_2(aq) + 2\text{NaI}(aq) \rightarrow \text{PbI}_2(s) + 2\text{NaNO}_3(aq)$ Which technique is used to separate the lead(II) iodide from the mixture?

May/June 2024

Give the name of the process used to change sulfur dioxide into sulfur trioxide in sulfuric acid manufacture.

May/June 2024

Give the names of two aqueous solutions that, when mixed, form a precipitate of lead(II) bromide.

May/June 2024

Name the industrial process used to make ammonia from nitrogen.

May/June 2024

An excess of solid magnesium oxide is placed into dilute nitric acid. What separation technique is then used to remove the unreacted solid magnesium oxide once the reaction has ended?

May/June 2025

Which method is used to separate a mixture of liquids that have different boiling points?

May/June 2025

Fractional distillation is used to divide petroleum into several useful fractions. Which statement about the properties of petroleum fractions is correct?

May/June 2025

Lead(II) sulfate is a salt that is insoluble. Which process would not be used to obtain a pure sample of this salt?

May/June 2025

Which method is employed to obtain copper(II) sulfate crystals from a copper(II) sulfate aqueous solution?

May/June 2025

A mixture made up of an aqueous salt and an insoluble salt is filtered. Which row shows X and Y?

May/June 2025

The procedure for separating a mixture that contains a soluble solid and an insoluble solid is shown below. • The mixture is added to a suitable ……1…… so that a solution forms. • It is then stirred and poured through a filter funnel fitted with filter paper. • The insoluble solid stays on the filter paper as the ……2…… . Which words should be placed in gaps 1 and 2?

May/June 2025

What pieces of apparatus are used to separate a mixture of liquids that have different boiling points?

May/June 2025

One sample of sea-water is distilled, whereas another sample of sea-water is filtered. Which statement about the samples is correct?

Oct/Nov 2016

The table provides details of the solubility of four solids, P, Q, R and S. A student tried to separate mixtures containing these solids by using this procedure. 1. Place the mixture in a beaker of water and stir it. 2. Filter the mixture. 3. Crystallise one of the solids from the filtrate. Which of the following mixtures could not be separated using this procedure?

Oct/Nov 2016

A sample includes a mixture of powdered limestone (calcium carbonate), sugar and wax. What is the correct method for obtaining a pure sample of sugar?

Oct/Nov 2016

A solid X is purified through five steps. The diagram shows the first four stages of the purification. In step 5, how is a pure sample of solid X obtained from mixture Y?

Oct/Nov 2016

The table shows solubility information for four solids, P, Q, R and S. A student tried to separate mixtures made from these solids using the procedure below: 1 Put the mixture into a beaker of water and stir it. 2 Filter the mixture. 3 Crystallise one of the solids from the filtrate. Which of the following mixtures could not be separated by this method?

Oct/Nov 2016

A sample is made up of powdered limestone (calcium carbonate), sugar and wax. Which is the correct method to obtain a pure sample of sugar?

Oct/Nov 2016

A solid X is cleaned up in five stages. The diagram shows the first four stages of the purification. In step 5, how is a pure sample of solid X obtained from mixture Y?

Oct/Nov 2016

The table provides details on five substances.

Oct/Nov 2016

Zinc sulfate is produced by reacting an excess of zinc oxide with dilute sulfuric acid. The leftover zinc oxide is then separated from the solution. Which process is used to recover solid zinc sulfate from this solution?

Oct/Nov 2017

What method can be used to separate a salt-and-water mixture so that both components are obtained?

Oct/Nov 2017

The apparatus shown is used for separating a mixture. Which mixture is it?

Oct/Nov 2017

Which method is used to obtain copper(II) sulfate crystals from an aqueous solution of copper(II) sulfate?

Oct/Nov 2017

Zinc sulfate is produced by allowing an excess of zinc oxide to react with dilute sulfuric acid. The unreacted zinc oxide is then filtered off from the solution. Which process is used to obtain solid zinc sulfate from the solution?

Oct/Nov 2017

The diagram depicts a fractionating column used for the fractional distillation of petroleum. The labels shown are: refinery gas, gasoline fraction, naphtha fraction, kerosene fraction, diesel oil fraction, fuel oil fraction, lubricating fraction and bitumen.

Oct/Nov 2017

A liquid used for cleaning metal contains the following compounds: ethanoic acid, ethanol, glycerol, sodium chloride and water.

Oct/Nov 2017

Petroleum is a blend of various hydrocarbons. Which process is used to divide petroleum into groups containing similar hydrocarbons?

Oct/Nov 2018

Petroleum consists of a blend of different hydrocarbons. Which process is used to split the petroleum into fractions of similar hydrocarbons?

Oct/Nov 2018

Petroleum contains a mixture of different hydrocarbons. Which process is used to separate petroleum into groups of hydrocarbons that are similar?

Oct/Nov 2018