Identification of ions

A small piece of lithium is added to a trough of water.

State two observations made when lithium reacts with water.

What are the products of the reaction?

After the reaction is complete, a few drops of universal indicator are added to the solution in the trough.

Explain the colour and pH of the solution in the trough.

Give the formula of the ion responsible for this pH.

Lithium ions can be identified using a flame test.

What flame colour indicates the presence of lithium ions?

When iron rusts, iron(III) oxide forms.

State two conditions needed for iron to rust.

What is the name of the process used to coat iron with zinc?

What is the correct order of reactivity of these four metals?

Describe a test to show that a solution contains Fe³⁺ ions.

test

result

A sample of iron(III) oxide reacts with excess carbon monoxide.

This is the equation for the reaction.

Explain why this is a redox reaction.

Calculate the minimum mass of iron(III) oxide needed to produce a theoretical yield of 28 g of iron.

[for Fe₂O₃ M_r = 160]

The actual yield of iron from this sample is 21 g.

Calculate the percentage yield of iron.

This question is about metals and metal compounds.

All metals are malleable and good conductors of electricity.

The diagram shows the structure of a metal.

Explain why metals are malleable.

Explain why metals are good conductors of electricity.

Two methods of obtaining a metal from a compound are electrolysis and extraction using carbon.

Explain, without giving practical details, which method is most suitable for extracting iron from iron(III) oxide.

A student has a solution of iron(II) sulfate and a solution of iron(III) sulfate.

Describe a chemical test the student could use to identify which solution is iron(II) sulfate.

This question is about the alkali metals.

A teacher demonstrates the reaction between sodium and water.

The teacher fills a trough with water and then adds a piece of sodium.

The sodium reacts with the water, forming bubbles of hydrogen gas and a colourless solution.

State two other observations that would be made.

Give a test to show that, at the end of the reaction, the solution contains sodium ions.

Lithium, sodium and potassium react in a similar way when added to water.

State, with reference to the electronic configurations of atoms, why these elements have similar reactions.

The table shows the atomic radius of a lithium atom, a sodium atom and a potassium atom.

Deduce the relationship between the atomic radius and the reactivity of the metals.

A technician needs to identify the solution in an unlabelled bottle.

The technician knows that the solution contains one of these compounds.

• iron(II) bromide

• iron(II) chloride

• iron(III) bromide

• iron(III) chloride

Describe how the technician can use chemical tests to identify the compound.

When chlorine gas is passed over heated iron powder, iron(III) chloride forms.

This is the equation for the reaction.

0.060 mol of chlorine gas is passed over 2.8 g of iron powder.

Show by calculation that the iron powder is in excess.

When iron(III) chloride dissolves in water, an acidic solution forms.

Give the colour of litmus in this solution.

Give the formula of the ion that causes the solution to be acidic.

The diagram shows two pieces of apparatus used in a titration.

Give the names of these pieces of apparatus.

Give the name of a suitable indicator that can be used in an acid-alkali titration.

A student does a titration using sodium carbonate solution and dilute nitric acid.

This is the equation for the reaction.

The table shows the concentrations of the two solutions and the volume of sodium carbonate used in the titration.

Use the equation and the data in the table to answer these questions.

Calculate the volume of dilute nitric acid that the student would need to neutralise the sodium carbonate solution.

Calculate the volume, in cm³, of carbon dioxide gas at rtp that would be produced from the 25.0 cm³ of the sodium carbonate solution.

[at rtp, molar volume = 24 000 cm³]

Describe a test to show that sodium carbonate solution contains carbonate ions.

This question is about lithium and some of its compounds.

A small piece of lithium is added to a trough containing water.

The lithium floats on the surface of the water and a vigorous reaction occurs.

Give two other observations when lithium reacts with water.

A few drops of methyl orange are added to the solution in the trough.

Explain the final colour of the solution.

An unlabelled bottle containing a white powder is found in a laboratory.

Describe tests to show that the white powder in the bottle is lithium carbonate.

Lithium carbonate has ionic bonding.

State what is meant by the term ionic bonding.

This question is about ionic compounds.

Calcium nitrate has the formula Ca(NO₃)₂

Give the formula of each ion in calcium nitrate.

calcium ion

nitrate ion

Explain why calcium nitrate has a high melting point.

Refer to structure and bonding in your answer.

Calcium nitrate decomposes when heated.

Complete the chemical equation for the decomposition of calcium nitrate.

A student has four unlabelled beakers, each containing a colourless solution of a different salt.

These are the four salt solutions.

• calcium bromide

• calcium chloride

• sodium chloride

• sodium sulfate

Describe a series of tests to identify each solution.

Do not refer to safety precautions in your answer.

When copper(II) sulfate solution is electrolysed, copper forms at the negative electrode.

A student uses this apparatus to investigate the electrolysis of copper(II) sulfate solution.

Describe how the student could test a sample of copper(II) sulfate solution to show that it contains copper(II) ions.

Describe how copper metal forms at the negative electrode.

State the appearance of the copper that forms on the negative electrode.

Oxygen forms at the positive electrode.

Give a test for oxygen.

Complete the half-equation for the formation of oxygen at the positive electrode.

2H₂O _........ +_........ +_........

State why the formation of oxygen at the positive electrode is an oxidation reaction.

This question is about elements, mixtures and compounds.

Which of these is the formula of a molecule of an element?

Which method can be used to separate an insoluble solid from a liquid?

Give the name of a method used to separate a mixture of liquids with different boiling points.

A student adds a crystal of substance X to some water in a beaker and leaves the beaker for one day.

The diagram shows the beaker immediately after adding the crystal, and after

Which equation gives the correct state symbols for a process that occurs in the beaker?

Which other process occurs in the beaker?

After one day the student does two tests on the liquid in the beaker.

The table shows the student’s results.

Identify substance X.

A student uses this apparatus to find the heat energy change when ammonium nitrate dissolves in water to form a solution.

This is the student’s method.

• add 50 cm³ of distilled water to the polystyrene cup and record the initial temperature of the water

• add a known mass of ammonium nitrate to the polystyrene cup and stir the mixture until all the solid dissolves

• record the minimum temperature of the ammonium nitrate solution

Give two reasons why the student stirs the mixture.

The diagram shows the minimum temperature of the solution.

Complete the table by giving the missing information.

Give both values to the nearest 0.1 °C.

The student repeats the experiment, again using 50 cm³ water, and finds that the temperature change is 3.9 °C.

Show that the heat energy change, Q, in this experiment is about 800 J.

[c = 4.2 J / g / °C for the solution]

[mass = 1.0 g for 1.0 cm³ of solution]

The student uses 2.8 g of ammonium nitrate in this experiment.

Calculate the enthalpy change, Δ H, in kJ / mol.

Include a sign in your answer.

[for NH₄NO₃, M_r = 80]

ΔH =_........ kJ / mol

Describe a test to show that the ammonium nitrate solution contains ammonium ions.

In another experiment the student adds anhydrous copper(II) sulfate to distilled water.

The table shows the student’s results.

Explain what the results show about the type of energy change that occurs when anhydrous copper(II) sulfate dissolves in water.

This question is about apparatus used in the laboratory.

Complete the table by giving the name of each piece of apparatus and a unit used for the quantity it measures.

The diagram shows apparatus used to obtain pure water from sodium chloride solution by simple distillation.

Explain why it is necessary for water to flow continuously in and out of the apparatus.

Describe a chemical test to show that the sodium chloride solution contains chloride ions.

Describe a physical test to show that the liquid in the conical flask is pure water.

This question is about ammonia and ammonium compounds.

Ammonia (NH₃) is a simple covalent molecule.

Draw a dot-and-cross diagram to show the bonding in a molecule of ammonia.

The table shows the names and formulae of some ammonium compounds.

Complete the table by giving the missing information.

When ammonia reacts with sulfuric acid, ammonium sulfate is formed.

Write a chemical equation for this reaction.

Describe a test for ammonium ions.

The table gives some information about ammonia and ammonium compounds.

Calculate the percentage of nitrogen in ammonium nitrate.

[M_r of NH₄NO₃ = 80]

Fertilisers add nitrogen to the soil to help plants grow.

Ammonia and ammonium sulfate can both be used as fertilisers.

Discuss the advantages and disadvantages of using each of these compounds as fertilisers.

Use information from the table in your answer.

[pH of rainwater is approximately 5.6]

This question is about Group 7, the halogens.

Which halogen has the palest colour?

Which halogen is a solid at room temperature?

The table shows the electronic configurations of a fluorine atom and a chlorine atom.

Explain the relative reactivities of fluorine and chlorine using the information in the table.

Lithium reacts with chlorine to form lithium chloride.

Write a chemical equation for the reaction of lithium with chlorine.

Describe tests to show that the product of the reaction is lithium chloride.

This question is about sodium oxide, Na₂O

The diagram shows the electronic configuration of atoms of sodium and oxygen.

Describe the changes in the electronic configuration of the atoms of sodium and oxygen to form the ions in sodium oxide.

Calculate the relative formula mass (M_r) of sodium oxide, Na₂O, using information from the Periodic Table.

Explain why solid sodium oxide does not conduct electricity.

Give a test to show that sodium oxide contains sodium ions.

When sodium oxide is heated it reacts to form sodium metal and sodium peroxide, Na₂O₂

Complete the equation for this reaction.

This question is about salts.

Soluble salts can be prepared by the reaction between a metal oxide and an acid.

The equation for this type of reaction is

metal oxide + acid salt + water

State the name given to this type of reaction.

State, in terms of protons, what happens in this reaction.

A student is given 50 cm³ of dilute sulfuric acid and a bottle of solid copper(II) carbonate.

Describe the method that the student should use to prepare a saturated solution of copper(II) sulfate.

In your answer, refer to the pieces of apparatus that the student should use.

The student produces dry crystals of hydrated copper(II) sulfate from the saturated solution.

He calculates that 6.40 g of dry crystals should be formed.

The mass of dry crystals he actually obtains is 1.80 g less than he calculated.

Calculate the student’s percentage yield.

Give your answer to one decimal place.

Gypsum is hydrated calcium sulfate.

A sample of gypsum contains 79% of calcium sulfate by mass.

Calculate the value of x in CaSO₄.xH₂O

Describe a test for calcium ions in the sample of gypsum.

This question is about elements in Group 7 of the Periodic Table and their compounds.

Give the name of this group of elements.

State the colour of chlorine gas.

Give a test for chlorine gas.

Give a test to show that a solution contains iodide ions.

A student compares the reactivity of the elements bromine, chlorine and iodine.

He mixes these pairs of solutions and observes the reactions that occur.

• chlorine solution and potassium bromide solution

• bromine solution and potassium iodide solution

Explain how the reactions can be used to show the order of reactivity of the three elements.

Include the colour change that the student would observe in each reaction.

This question is about some of the alkali metals and their compounds.

When a teacher drops a small piece of sodium into a trough of cold water, she observes bubbles of gas.

Give two other observations that would be made when sodium reacts with cold water.

Lithium reacts with fluorine to form the compound lithium fluoride.

Give a chemical equation for this reaction.

Give a test to show that lithium fluoride contains lithium ions.

Draw diagrams to show the arrangement of the electrons in a lithium ion and in a fluoride ion.

Include the charge on each ion.

lithium ion
fluoride ion

The table shows the electronic configurations of sodium and potassium.

Explain, in terms of their electronic configurations, why potassium is more reactive than sodium.

A student is provided with a bottle containing a colourless solution X.

Solution X is thought to be dilute sulfuric acid of concentration 0.10 mol/dm³.

The student does some experiments on samples of solution X to try to show that it is dilute sulfuric acid.

The student adds a few drops of litmus to a sample of solution X.

The litmus turns red.

The student knows that the products of the electrolysis of dilute sulfuric acid are hydrogen and oxygen.

She carries out the electrolysis using this apparatus.

Suggest why the student does not use zinc electrodes in her experiment.

State what is observed at both the anode and the cathode during the electrolysis.

Which of these tests shows that the gas formed at the cathode is hydrogen?

Describe a test to show that solution X contains sulfate ions.

The student then does a titration to see if the concentration of the dilute sulfuric acid is 0.10 mol/dm³.

She measures 25.0 cm³ of potassium hydroxide solution into a conical flask, and then adds a few drops of indicator solution.

Name the piece of apparatus the student should use to measure 25.0 cm³ of the potassium hydroxide solution.

The concentration of potassium hydroxide in the solution is 0.125 mol/dm³.

Calculate the amount, in mol, of KOH in 25.0 cm³ of this solution.

The equation for the reaction in the titration is

Calculate the volume, in cm³, of 0.10 mol/dm³ sulfuric acid needed to neutralise 25.0 cm³ of the potassium hydroxide solution.

This question is about ammonium chloride.

Give the formula of the ammonium ion.

Describe a test to show that ammonium chloride contains ammonium ions.

The equation shows the thermal decomposition of ammonium chloride.

State what the symbol indicates about this reaction.

The diagram shows the formation of ammonium chloride in a glass tube.

cotton wool soaked in cotton wool soaked in concentrated hydrochloric acid
ammonium chloride concentrated ammonia solution

Explain how the mean speed of ammonia molecules compares with the mean speed of hydrogen chloride molecules.

Gas particles travel very quickly.

Give two reasons why it takes several minutes for the ammonium chloride to form.

This question is about some of the halogens and their compounds.

Which element is a liquid at room temperature?

Which element has the palest colour?

Which element is the least reactive?

A teacher uses displacement reactions to demonstrate the reactivities of some halogens.

She adds solutions of chlorine, bromine and iodine separately to three different sodium halide solutions.

The table shows some of the teacher’s results.

A change in colour of the solution indicates that a reaction has occurred.

Complete the table by predicting the missing results.

State why the teacher does not add bromine solution to sodium bromide solution.

The word equation for the reaction of bromine with sodium iodide is

bromine + sodium iodide iodine + sodium bromide

Write a chemical equation for this reaction.

A technician sees an unlabelled bottle containing a liquid.

He knows that the liquid is a solution of one of these compounds.

● copper(II) chloride

● copper(II) bromide

● iron(II) chloride

● iron(II) bromide

Describe chemical tests that the technician could use to identify the compound in the solution.

The diagram shows the arrangement of electrons in an atom of calcium and in an atom of chlorine.

Describe, in terms of electrons, what happens when calcium reacts with chlorine to form the ionic compound calcium chloride, CaCl₂

Describe tests to show that an aqueous solution of calcium chloride contains calcium ions and chloride ions.

Solid calcium chloride does not conduct electricity. Aqueous solutions of calcium chloride do conduct electricity.

A student uses this method to investigate how the conductivity of a solution changes when calcium chloride is dissolved in pure water.

Step 1 add 100 cm³ of pure water to a beaker

Step 2 add one spatula of solid calcium chloride to the beaker

Step 3 stir the solution

Step 4 measure the conductivity of the solution

Step 5 repeat until nine spatulas of solid calcium chloride have been added

The table shows the student’s results.

Plot the results on the grid and draw two straight lines of best fit.

Ignore the anomalous result.

State the trend shown on the graph for the first six spatulas of calcium chloride.

Suggest an error the student could have made to cause the anomalous result.

Describe another way to make solid calcium chloride conduct electricity.

This question is about elements, compounds and mixtures.

Name the element that burns with a lilac flame.

Name the technique used to separate the mixture of colours in black ink.

The box gives the names of some substances.

Choose substances from the box to answer these questions.

Identify the compound.

Identify the mixture.

Identify the non‑metal element that is a solid at room temperature.

Solutions of silver nitrate and potassium chloride react together to make the insoluble salt, silver chloride.

A student uses this method to prepare a sample of silver chloride.

Step 1 add 25 cm³ of silver nitrate solution to a conical flask

Step 2 add potassium chloride solution to the flask

Step 3 filter off the silver chloride

What term is used for this reaction?

Give two more steps that will produce a pure, dry sample of silver chloride.

Acidified silver nitrate solution is used to test for chloride ions.

Give a reason why hydrochloric acid is not used to acidify silver nitrate solution.

The chemical equation for the reaction between solutions of silver nitrate and potassium chloride is

AgNO₃(aq) + KCl(aq) AgCl(s) + KNO₃(aq)

A student adds an excess of potassium chloride solution to 25.0 cm³ of 0.100 mol/dm³ silver nitrate solution.

Calculate the maximum mass of silver chloride, in grams, that can be produced.

[M_r of AgCl = 143.5]