4CH1/1C — June 2019 (Edexcel IGCSE Chemistry): Past Paper

Potassium permanganate is a purple solid that is soluble in water. A crystal of potassium permanganate is placed in a beaker containing water

After a short time, the crystal becomes smaller and the liquid at the bottom of the beaker becomes purple. Which statement explains this observation?

The beaker is left until there is no further change in the appearance of the liquid.

Which statement describes the final appearance of the liquid?

Which process causes this change in appearance?

The formula of potassium permanganate is KMnO₄ How many different elements are there in potassium permanganate?

The diagram shows part of the Periodic Table, with elements represented by the letters L, M, Q, R and T. The letters in the diagram represent elements but are not their chemical symbols

Give the letter from the diagram that represents a noble gas.

Elements L and M are in the same group. State why they have similar chemical reactions.

An atom of element Q has 31 protons. Use this information to explain how you can determine the number of protons in an atom of element R.

A student does these two tests on a solution made from a white solid.

Give the formula of the ion that produces the red flame.

Name the cream precipitate.

Identify the white solid.

The student uses a clean metal wire in the flame test.

State why the wire should be clean when used in the flame test.

The table lists properties of some metals. Add ticks (✓) to the table to show the two properties needed in a metal wire used in a flame test. Property good conductor of electricity high density high melting point unreactive

A student uses this apparatus to investigate the colours in four different inks, A, B, C and D

Explain two mistakes the student made when setting up his experiment. 1 2

Another student does the experiment but does not make any mistakes. The diagram shows her results

State how many colours ink D contains.

State which of the inks tested could be mixed together to make ink D.

Explain which of the inks tested is insoluble in water.

In 1937 an airship full of hydrogen gas flew from Germany to America.

Which property of hydrogen makes it a suitable gas to use in an airship?

Explain why helium is now used in airships instead of hydrogen.

Hydrogen is used to manufacture ammonia, NH₃ Hydrogen is reacted with nitrogen using an iron catalyst.

Give a chemical equation for this reaction.

State why a catalyst is used in this reaction.

The reactions of metals with water and with dilute sulfuric acid can be used to determine the order of reactivity of the metals. The table shows the reactions of four metals, W, X, Y and Z, with water and with dilute sulfuric acid

What is the order of reactivity of these metals? most reactive least reactive

State which metal, W, X, Y or Z, could be copper.

State which metal, W, X, Y or Z, could be magnesium.

A displacement reaction can also be used to decide the order of reactivity of two metals. State two observations made when an excess of magnesium powder is added to an aqueous solution of copper(II) sulfate. 1 2

Diamond, graphite and silicon dioxide all have giant covalent structures. The diagram shows the structures of these three substances

Explain why silicon dioxide has a high melting point.

Explain why graphite conducts electricity.

State why diamond is hard but graphite is soft.

Ethene (C₂H₄) can be converted into chloroethene (C₂H₃Cl) in a two-stage process.

The first stage is to convert ethene into 1,2-dichloroethane, C₂H₄Cl₂ Ethene is reacted with hydrogen chloride and oxygen. Complete the chemical equation for this reaction C₂H₄ + HCl + O₂ → C₂H₄Cl₂ + H₂O

In the second stage, 1,2-dichloroethane is converted into chloroethene. C₂H₄Cl₂ → C₂H₃Cl + HCl This is a thermal decomposition reaction. State what is meant by the term thermal decomposition.

The diagram shows the displayed formula of chloroethene

State why chloroethene is described as an unsaturated compound.

Describe a test to show that chloroethene is unsaturated.

Name the polymer formed from chloroethene.

Halon 1301 is a compound used in some fire extinguishers. Halon 1301 has the percentage composition by mass of C 8.05% Br 53.69% F 38

Show, by calculation, that the empirical formula of this compound is CBrF₃

The diagram shows the displayed formula of a molecule of Halon 1301. F Br C F F Draw a dot-and-cross diagram to show all the outer electrons in this molecule.

The boiling point of Halon 1301 is −58 °C. Explain why Halon 1301 has a low boiling point.

There are three isomers with the molecular formula C5H12.

One of these isomers is pentane. The displayed formula for pentane is:

State what is meant by the term isomers.

Draw the displayed formula for another isomer of C₅H₁₂

Pentane reacts with bromine in the presence of ultraviolet radiation.

Complete the equation for this reaction. C₅H₁₂ + Br₂ → +

Give the name of this type of reaction.

The gas burned in a Bunsen burner is methane. The equation for the complete combustion of methane is CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)

Calculate the mass of oxygen required to react with 32 g of methane. [Mr of methane = 16] mass of oxygen = g

The diagram shows methane burning in air. It also shows how the two gases formed are collected and tested. methane burning U-tube ice and water limewater to pump

Explain why water collects in the U-tube.

Describe how anhydrous copper(II) sulfate is used to test for water.

Explain the change in appearance of the limewater.

A student uses this apparatus to investigate the temperature change that occurs when ammonium nitrate dissolves in water.

The student's results:

• Starting temperature of water: 20.0 °C
• Lowest temperature of solution: 14.2 °C

Use the results of the experiment to explain what type of reaction is taking place when ammonium nitrate is added to water.

Show that the heat energy change, Q, is about 2400 J. [mass of 1.00 cm³ of solution = 1.00 g] [for the solution, c = 4.18 J/g/ °C ] Q = J

Use your answer to part (b) to calculate the enthalpy change, ∆H, in kilojoules per mole of ammonium nitrate. [Mr of ammonium nitrate = 80.0] Include a sign in your answer. ∆H = kJ/mol

A student uses this apparatus to investigate the rate of reaction between magnesium and an excess of dilute hydrochloric acid.

The student measures the volume of hydrogen produced every 10 seconds.

Plot the student’s results on the grid.

Draw a curve of best fit. 100 Volume of hydrogen in cm³ 0 20 40 60 80 Time in s

The student repeats the experiment using ● 0.043 g of magnesium ribbon ● 50 cm³ of 2.00 mol/dm³ hydrochloric acid Draw, on the grid in part (a), the curve you would expect in this experiment. Label this curve Y.

The student repeats the experiment again, using ● 0.086 g of magnesium ribbon ● 50 cm³ of 2.00 mol/dm³ hydrochloric acid ● a slightly higher temperature than the first experiment Draw, on the grid in part (a), the curve you would expect in this experiment. Label this curve Z.

The expected volume of gas produced in the first experiment is 86 cm³. Suggest why the volume collected is less than the expected volume.

The student uses a graduated beaker to measure the volume of dilute hydrochloric acid. Explain why it is not necessary to use a measuring cylinder in this experiment.

The ionic equation for the reaction between magnesium and hydrochloric acid is Mg(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂(g) Use the information in this equation, and the particle collision theory, to explain why the rate of reaction decreases during each of the experiments.

A salt can be made by reacting an acid with an insoluble base. A student has a sample of copper(II) oxide. The student uses this method. Stage 1 pour 50 cm³ of dilute sulfuric acid into a beaker Stage 2 warm the acid using a Bunsen burner Stage 3 add a small amount of copper(II) oxide to the warm acid and stir the mixture Stage 4 add further amounts of copper(II) oxide until copper(II) oxide is in excess Stage 5 filter the mixture Stage 6 obtain crystals from the filtrate

State why the acid is warmed in stage 2.

State how the student would know that the copper(II) oxide is in excess in stage 4.

State why the mixture is filtered in stage 5.

State the colour of the filtrate obtained in stage 5.

Describe how the student could obtain a pure, dry sample of hydrated copper(II) sulfate crystals from the filtrate in stage 6.

The overall equation for the formation of hydrated copper(II) sulfate crystals from copper(II) oxide is CuO(s) + H₂SO₄(aq) + 4H₂O(l) → CuSO₄.5H₂O(s)

In an experiment, a student completely reacts 9.54 g copper(II) oxide. Show that the maximum possible mass of CuSO₄.5H₂O crystals that can be obtained is about 30 g. [Mr of CuO = 79.5 Mr of CuSO₄.5H₂O = 249.5] Give your answer to an appropriate number of significant figures. mass = g

In this experiment, the actual yield of CuSO₄.5H₂O crystals is 23.92 g. Calculate the percentage yield of CuSO₄.5H₂O percentage yield = %

Hydrated ammonium iron(III) sulfate is a violet solid that has the formula (NH₄)₂SO₄.Fe₂(SO₄)₃.xH₂O The table shows some tests done on three separate samples of the solid. Test Observation Dissolve the solid in water and add acidified barium chloride solution. Dissolve the solid in water and add sodium hydroxide solution. Add sodium hydroxide solution to the solid and warm the mixture. Test the gas given off with moist universal indicator paper.

Complete the table to show the observation made in each test.

A student needs to find the value of x in the formula (NH₄)₂SO₄.Fe₂(SO₄)₃.xH₂O He uses this apparatus. The hydrated solid decomposes when heated gently. The equation for the reaction is (NH₄)₂SO₄.Fe₂(SO₄)₃.xH₂O → (NH₄)₂SO₄.Fe₂(SO₄)₃ + xH₂O The table shows the student's results

Calculate the mass of (NH₄)₂SO₄.Fe₂(SO₄)₃ produced by heating. mass of (NH₄)₂SO₄.Fe₂(SO₄)₃ = g

Calculate the mass of water produced. mass of water = g

Calculate the value of x. [Mr of (NH₄)₂SO₄.Fe₂(SO₄)₃ = 532 and Mr of H₂O = 18] Give your answer to the nearest whole number. value of x =