Identification of ions and gases

The table presents the outcomes of two reactions of an aqueous solution of a salt. Adding excess aqueous sodium hydroxide produces a white precipitate. Dilute nitric acid and aqueous silver nitrate produce a yellow precipitate. Which salt is it?

May/June 2015

An ammonium salt was mixed with excess hot aqueous sodium hydroxide, and ammonia gas was released. After ammonia was no longer being produced, aluminium was introduced into the solution left behind, and further ammonia gas was evolved. Which ammonium salt was it?

May/June 2015

The table presents the outcomes of two reactions involving an aqueous solution of a salt. What might the salt be?

May/June 2015

The diagram outlines several reactions of iron(II) sulfate, FeSO$_4$.

May/June 2015

The table below lists the tests carried out on compound $M$ by a student and the conclusions drawn from the observations.

May/June 2015

The table summarises the tests a student carries out on compound $V$.

May/June 2015

Which row correctly names the gas?

May/June 2016

L is a compound consisting of two ions.

May/June 2016

State a test and the observation that would show that the nitrate ion, $\text{NO}_3^- (aq)$, is present.

May/June 2016

Gas X shows these properties: 1 colourless 2 does not affect either red or blue litmus paper 3 does not change limewater 4 flammable What is gas X?

May/June 2017

A zinc chloride solution in water is examined by adding reagents. Which observation would be correct?

May/June 2017

Reagents are added to an aqueous solution of zinc chloride. Which observation is correct?

May/June 2017

A student is given compound M, which has one cation and one anion. He carries out the following tests to identify the two ions.

May/June 2017

A student puts a known mass of magnesium ribbon into $100\,\text{cm}^3$ of dilute hydrochloric acid, which is in excess, in the apparatus illustrated. Hydrogen gas is produced.

May/June 2017

The following aqueous solutions of four different metal sulfates are supplied: • chromium(III) sulfate • copper(II) sulfate • iron(II) sulfate • iron(III) sulfate

May/June 2017

Trials were performed on an aqueous solution of an unidentified compound, $P$. The observations are shown in the table. Aqueous sodium hydroxide added: green precipitate, soluble in excess to give a green solution. Dilute nitric acid added, followed by aqueous barium nitrate: white precipitate. Dilute nitric acid added, followed by aqueous silver nitrate: no precipitate. Which ions are present in $P$?

May/June 2018

Which row shows the right tests for identifying both ammonia and sulfur dioxide?

May/June 2018

Select the gases to respond to the questions. argon carbon dioxide carbon monoxide ethane hydrogen methane neon ozone sulfur dioxide sulfur trioxide You may use each gas one time, more than once, or not use it at all.

May/June 2018

Solid L is a mixture made up of two compounds. These compounds have the same positive ion but different negative ions. The table lists the tests a student carries out on L. Fill in the table with the observations for tests (a) and (c), and write the conclusion for test (b). If any gases are produced, they should be named and identified using an appropriate test and observation.

May/June 2018

A pair of solids, L and M, are combined. L dissolves in water, whereas M does not dissolve in water.

May/June 2018

Once the solution of $X$ has been acidified using dilute nitric acid, it reacts with aqueous silver nitrate and forms a white precipitate. What might $X$ be?

May/June 2019

The diagrams illustrate four distinct ways of gathering gases. Which method is appropriate for collecting a gas with the properties described?

May/June 2019

Which anions are found in aqueous copper(II) sulfate?

May/June 2019

When the colourless solution of X is acidified with dilute nitric acid and then mixed with aqueous silver nitrate, a white precipitate is formed. What substance could X be?

May/June 2019

Ammonium carbonate, $(\text{NH}_4)_2\text{CO}_3$, is a white solid that breaks down on heating. $(\text{NH}_4)_2\text{CO}_3(s)\rightarrow2\text{NH}_3(g)+\text{CO}_2(g)+\text{H}_2\text{O}(g)$

May/June 2019

Ammonium iodide, NH$_4$I, is a white solid that decomposes on heating. $\text{NH}_4\text{I(s)} \rightarrow \text{NH}_3(g) + \text{HI}(g)$

May/June 2019

A sample of river water is examined for pollutants.

May/June 2019

Mineral alstonite has two different cations, but just one anion. The table lists the tests that a student performs on a sample of alstonite. Complete the table. Name any gases that are produced.

May/June 2019

J is a solution in water. When aqueous sodium hydroxide is added to J, a green precipitate forms. The mixture is then heated, but no gas is produced. Aluminium foil is added to the warmed mixture, and a gas is produced that changes damp red litmus paper blue. Which ions may be present in J?

May/June 2021

Gas X shows the following characteristics. 1 colourless 2 it has no action on either damp red or blue litmus papers 3 it produces no change in limewater 4 flammable What is gas X?

May/June 2021

Four test-tubes are arranged as illustrated, containing $\text{AgNO}_3(\text{aq})$, $\text{Cu(NO}_3)_2(\text{aq})$, $\text{Pb(NO}_3)_2(\text{aq})$ and $\text{NaNO}_3(\text{aq})$. What happens when dilute hydrochloric acid is added to each test-tube? Key: $\times$ = clear solution, $\checkmark$ = precipitate formed.

May/June 2021

A colourless aqueous solution of J contains cations and chloride ions. When separate portions of the solution are tested, each produces a white precipitate with a few drops of aqueous sodium hydroxide and with a few drops of aqueous ammonia. Which statement about J is correct?

May/June 2021

Gas X has the following properties. 1. without colour 2. does not change either damp red or blue litmus papers 3. does not change limewater 4. can be ignited Which gas is X?

May/June 2021

A student carries out a sequence of tests on a mixture of ionic compounds in aqueous solution. Complete the table shown. Name any gases produced and describe the tests used to identify them.

May/June 2021

The solution contains two different cations plus one anion.

May/June 2021

Separate tests are carried out on two samples of a colourless solution using aqueous sodium hydroxide, $\text{NaOH(aq)}$, and aqueous ammonia, $\text{NH}_3\text{(aq)}$, and the observations are noted. • A white precipitate appears when two drops of $\text{NaOH(aq)}$ are added. In excess $\text{NaOH(aq)}$, this precipitate dissolves. • A white precipitate appears when two drops of $\text{NH}_3\text{(aq)}$ are added. In excess $\text{NH}_3\text{(aq)}$, this precipitate dissolves. What conclusion can be drawn from these observations?

May/June 2022

Aqueous silver nitrate, $\text{AgNO}_3$, reacts with aqueous potassium chromate(VI), $\text{K}_2\text{CrO}_4$, to form a yellow precipitate. What is the ionic equation for this reaction?

May/June 2022

A colourless solid does not dissolve in water. Which cations and anions might be present in this compound?

May/June 2022

Several reactions of an aqueous solution of compound $X$ are observed. On adding a few drops of aqueous sodium hydroxide, a white precipitate forms. When dilute nitric acid is then added and the mixture is warmed, a gas is produced. This gas decolourises acidified potassium manganate(VII). If dilute nitric acid and aqueous barium nitrate are added, there is no visible change. What can be deduced about the identity of $X$?

May/June 2022

Pick one compound from the list below to answer the questions. NH$_4$Cl BaSO$_4$ KI K$_2$SO$_3$ Mg(NO$_3$)$_2$ NaOCOCH$_3$ Na$_2$CO$_3$ Na$_3$PO$_4$ ZnSO$_4$ Any compound may be used once, more than once, or not used at all. State which compound:

May/June 2022

Use the compounds listed below to answer the questions. AgCl Ba(NO$_3$)$_2$ KI KMnO$_4$ K$_2$SO$_3$ Mg(NO$_3$)$_2$ Na$_2$CO$_3$ Na$_3$N NH$_4$Cl ZnSO$_4$ Each compound can be chosen once, more than once, or not used. State which compound:

May/June 2022

A student is given a mixture of solid ionic compounds. They put the mixture into a beaker of water and stir the contents. The beaker now contains a colourless solution and an insoluble black solid.

May/June 2022

One cation is present in the solution together with two different anions.

May/June 2022

Aqueous sodium hydroxide is used to identify the ions present in the aqueous solutions of compounds Q and R. The outcomes are displayed. Which row is correct?

May/June 2023

A student carries out an investigation using solution W and copper(II) carbonate.

May/June 2023

A student carries out an investigation on solution W and solid X.

May/June 2023

The table presents the outcomes of a set of tests on two substances, X and Y. Which row indicates the identities of the ions present in X and Y?

May/June 2024

The presence of water may be tested using either anhydrous cobalt(II) chloride or anhydrous copper(II) sulfate. Which observation would be correct when water is present?

May/June 2024

A student carries out a sequence of experiments to examine solution R.

May/June 2024

A student carries out a set of experiments to investigate solution $R$.

May/June 2024

Two compounds, $P$ and $Q$, are each examined using samples. The outcome of every test is displayed. Which row gives the identities of the ions present in $P$ and $Q$?

May/June 2025

A sample of white powder, X, is dissolved in water. Separate portions of this solution are tested, and the observations are recorded in the table. What is X?

May/June 2025

Select one salt from the list below to answer the questions. aluminium chloride barium sulfate calcium chloride copper(II) sulfate magnesium chloride potassium iodide potassium manganate(VII) silver nitrate sodium bromide sodium sulfite Each salt may be used once, more than once, or not used at all. State which salt should be chosen:

May/June 2025

Select the required answers from the salts listed below. aluminium sulfate barium chloride copper(II) nitrate copper(II) sulfate magnesium chloride potassium iodide potassium manganate(VII) silver chloride sodium bromide Each salt may be chosen once, more than once, or not chosen at all. State the salt:

May/June 2025

A student examines two aqueous samples, W and X.

May/June 2025

A student examines solid A and aqueous solution B. Solid A is a metal carbonate. Solution B has only one cation and one anion.

May/June 2025

When a solution of sodium carbonate was added to tap water, a white precipitate appeared. Which ion in the tap water was responsible for this precipitate forming?

Oct/Nov 2015

A colourless solution is stated to contain a sodium salt. Experiments were done to find out which anion is present in the solution. Test results: - dilute hydrochloric acid: no observable change - dilute nitric acid followed by aqueous silver nitrate: no precipitate formed - dilute nitric acid followed by aqueous barium nitrate: no precipitate formed Which anion might the solution contain?

Oct/Nov 2015

The table below summarises the tests that a student carries out on compound $Z$.

Oct/Nov 2015

Which one of the following would not react with each other to produce a precipitate? (a) aqueous sodium hydroxide and aqueous ammonium chloride (b) aqueous silver nitrate and aqueous sodium chloride (c) aqueous sodium hydroxide and aqueous iron(II) sulfate (d) aqueous barium nitrate and aqueous magnesium sulfate

Oct/Nov 2015

Compound L is a solid. The table below records the tests that a student carries out on compound L.

Oct/Nov 2015

Add aqueous sodium hydroxide to one portion of a colourless solution. Add aqueous ammonia to another separate portion of the same colourless solution. In each test, a white precipitate is produced and then dissolves in excess reagent. Which positive ion is present in the solution?

Oct/Nov 2016

The table lists the observations obtained after various reagents were added to an aqueous solution of salt Z. What is Z?

Oct/Nov 2016

When a solution containing lead(II) ions is combined with a solution containing iodide ions, a yellow precipitate is produced. What is the equation for the reaction taking place?

Oct/Nov 2016

Select from the compounds listed below to answer the questions that follow. Ba(NO$_3$)$_2$ CaCO$_3$ CaO CH$_4$ C$_3$H$_8$ Fe$_2$O$_3$ KMnO$_4$ NaNO$_3$ NO SO$_2$ V$_2$O$_5$ Zn(NO$_3$)$_2$ Each compound may be used once, more than once, or not used at all. Which compound

Oct/Nov 2016

Pick answers for the questions below from the compounds listed here. BaCl$_2$ C$_2$H$_4$ C$_3$H$_4$ C$_3$H$_8$ CO CO$_2$ K$_2$SO$_4$ Na$_3$PO$_4$ SO$_2$ ZnSO$_4$ Any of these compounds may be used once, more than once, or not used at all.

Oct/Nov 2016

Farmers apply fertilisers such as ammonium sulfate to the soil so that plant growth happens more quickly.

Oct/Nov 2016

The table outlines the tests carried out by a student on compound $L$. $L$ contains three different ions. Fill in the table by giving the conclusion for (a), the observations for (b)(i), (ii) and (iii), the conclusions for (c)(i) and (ii), and both the test and the observation that support the conclusion for test (d). Any gases given off should be identified by test, result and name.

Oct/Nov 2016

The table below lists the tests that a student performs on mixture $L$, which is composed of two compounds. $L$ contains three different ions.

Oct/Nov 2016

The outcomes of two tests on solution $X$ are displayed. When aqueous sodium hydroxide is added, a white precipitate forms and then dissolves in excess. When aqueous ammonia is added, a white precipitate forms and does not dissolve. Which ion is present in solution $X$?

Oct/Nov 2017

The outcomes of two tests carried out on solution $X$ are shown below. Aqueous sodium hydroxide: a white precipitate is formed, and the precipitate dissolves in excess. Aqueous ammonia: a white precipitate is formed, and the precipitate does not dissolve. Which ion is present in solution $X$?

Oct/Nov 2017

Which experiment will produce a white precipitate?

Oct/Nov 2017

The table below lists the tests that a student carries out on compound L.

Oct/Nov 2017

The table below lists the tests that a student carries out on compound $L$.

Oct/Nov 2017

Insoluble salts are made by mixing aqueous solutions of soluble salts, causing a precipitate to appear. Which pairs of aqueous solutions produce a precipitate? 1. barium chloride and nitric acid 2. barium chloride and sulfuric acid 3. barium nitrate and nitric acid 4. barium nitrate and sulfuric acid

Oct/Nov 2018

A colourless solution is obtained when a substance is mixed with water. If aqueous silver nitrate is then added in the presence of dilute nitric acid, a yellow precipitate appears. What is the likely identity of the substance?

Oct/Nov 2018

A compound dissolves in water and produces a colourless solution. If this solution is mixed with aqueous silver nitrate in the presence of dilute nitric acid, a yellow precipitate is formed. What is the likely identity of the substance?

Oct/Nov 2018

The student is given three bottles: dilute hydrochloric acid, aqueous sodium sulfate and ethanol.

Oct/Nov 2018

Solid $L$ consists of a mixture of two compounds. Both compounds have the same cation, but their anions are different.

Oct/Nov 2018

A student has been given three bottles of different aqueous solutions together with some reagents.

Oct/Nov 2018

Solid L is made up of two compounds. Each compound contains a different cation but the same anion.

Oct/Nov 2018

In which reaction is a white precipitate present once the reaction has finished?

Oct/Nov 2019

A student is given three aqueous solutions: aqueous zinc sulfate, aqueous copper(II) sulfate and aqueous calcium nitrate. The student carries out tests on the three aqueous samples by adding each reagent shown in the table. Record the observations in the table. Write ‘no reaction’ where appropriate.

Oct/Nov 2019

A student is given solutions of: • aqueous chromium(III) nitrate • aqueous iron(II) chloride • aqueous iron(III) chloride The student carries out tests on the three aqueous solutions by adding each reagent listed in the table. Record the observations in the table. Write ‘no reaction’ where appropriate.

Oct/Nov 2019

At room temperature and pressure, compound X exists as a crystalline solid. An aqueous solution of X is examined as follows. Test results: • Acidify with dilute nitric acid, then add aqueous barium nitrate: no observable change. • Add aqueous ammonia: a white precipitate forms, which dissolves in excess. What is a possible identity of X?

Oct/Nov 2020

When aqueous sodium hydroxide is introduced into a solution, a white precipitate is produced that dissolves on adding excess sodium hydroxide. Which ion might be present in the solution?

Oct/Nov 2020

Aqueous zinc chloride is tested using several reagents. Which observation is correct?

Oct/Nov 2020

If aqueous sodium hydroxide is added to a solution and a white precipitate is produced that then dissolves in excess sodium hydroxide, which ion may be present in the solution?

Oct/Nov 2020

Select from the compounds below to answer the questions. aluminium iodide ethanol glucose lead(IV) chloride lithium bromide magnesium carbonate methane potassium phosphate silver nitrate sodium sulfate sulfur dioxide Each compound may be used once, more than once, or not at all. Which compound:

Oct/Nov 2020

A drop of black ink is added to the bottom of a beaker of water. After some time, the colour spreads through the water. Explain this observation using the kinetic particle theory.

Oct/Nov 2020

Compound Q is made up of two cations and one anion. The table below records the tests a student carries out on compound Q. Complete the table using the test results. Identify any gases produced in the tests.

Oct/Nov 2020

A solid sample R contains two cations and one anion. The table lists the tests a student performs on R.

Oct/Nov 2020

When compound X is heated with an aqueous solution of compound Y, a gas is produced that turns red litmus blue. Which statements are correct?

Oct/Nov 2021

Aqueous zinc chloride is examined by adding reagents. Which observation is correct?

Oct/Nov 2021

A red-brown precipitate appears when aqueous sodium hydroxide is mixed with aqueous compound X. A white precipitate appears when dilute nitric acid is added first, followed by aqueous barium nitrate, to aqueous compound X. What is the identity of X?

Oct/Nov 2021

An aqueous solution containing zinc chloride is tested by adding reagents. Which observation is the correct one?

Oct/Nov 2021

The student is given three unlabelled bottles containing dilute sulfuric acid, aqueous calcium chloride and aqueous zinc chloride. In addition, the student has dilute nitric acid, aqueous barium nitrate and aqueous sodium hydroxide, with no other chemicals or indicators supplied.

Oct/Nov 2021

The solid R is composed of two cations and one anion.

Oct/Nov 2021

A student has three unlabelled bottles, and each one contains a solution. The student is told that the bottles contain: • dilute hydrochloric acid • aqueous aluminium sulfate • aqueous zinc sulfate The student is given: • dilute nitric acid • aqueous silver nitrate • aqueous ammonia and no other chemicals or indicators.

Oct/Nov 2021

A solid S has two cations and one anion. Complete the table. Name any gases produced in the tests.

Oct/Nov 2021