Edexcel GCSE Chemistry Paper 1 Higher November 2021 question paper 1CH0/1H

When heated, zinc carbonate decomposes to form zinc oxide and carbon dioxide gas.

A student investigated the decomposition of a sample of zinc carbonate.

The student used the following method.

step 1 the mass of an empty crucible was determined

step 2 a sample of zinc carbonate was placed into the crucible

step 3 the mass of the crucible and the zinc carbonate was determined

step 4 the crucible and zinc carbonate was heated for five minutes

step 5 the mass of the crucible and contents was determined.

Figure 1 shows the apparatus used.

Suggest how the student could confirm that the decomposition was complete.

The theoretical maximum yield of zinc oxide was 1.86 g.

The actual yield was 1.63 g.

Calculate the percentage yield of zinc oxide.

percentage yield =_........

Another student carried out the experiment using a similar method. The student used a blue, roaring Bunsen burner flame and placed a lid on the crucible.

State why the student used a blue, roaring flame and a lid.

why a blue, roaring flame_........

The scientist John Dalton lived over 200 years ago.

John Dalton suggested an early model of atoms.

When Dalton first described atoms he said that

• all elements are made of atoms

• atoms are not formed of any smaller particles

• all atoms of the same element are identical.

Give two differences between Dalton’s model of atoms and today’s model of atoms.

Dalton also investigated different gases.

One of the gases that Dalton investigated was ethene.

The structure of one molecule of ethene is shown in Figure 2.

Give the molecular formula and the empirical formula of ethene.

Another gas that Dalton investigated was chlorine.

Chlorine gas reacts with water. The two products are a solution of hydrogen chloride and the substance HC l O.

Complete the balanced equation for this reaction, including the three missing state symbols.

Hydrogen chloride solution is acidic.

The formulae of four ions are shown in Figure 3.

Give the formula of the ion in Figure 3 that causes the hydrogen chloride solution to be acidic.

An acid reacts with an alkali.

Give the name of this type of reaction.

A sample of potable water contains impurities.

Why is this sample of water potable even though it contains impurities?

Waste water can be used to produce drinking water. The processes used include sedimentation, filtration and chlorination.

What is sedimentation?

State why the waste water is filtered.

State the reason for chlorination.

Some salts can be added to waste water to remove impurities. In an experiment, different masses of salt A were added to 1000cm³ samples of waste water. The experiment was repeated with salt B. The percentages of impurities removed from the waste water are shown in Figure 4.

mass of salt in mg per 1000cm³ water

Figure 4

It was concluded that the best way to purify 1000cm³ of the waste water is to add 100 mg of salt B.

Use the information about salt A and salt B in Figure 4 to evaluate this conclusion.

Waste water may contain phosphate ions, PO₄^3-.

Aluminium ions react with phosphate ions to form aluminium phosphate.

Complete the ionic equation for the formation of aluminium phosphate in this reaction.

Aluminium alloys are used instead of pure aluminium in aircraft manufacture.

Explain, in terms of the arrangement of metal particles, why aluminium alloys are stronger than pure aluminium.

A 695.0 g sample of an aluminium-magnesium alloy contains 2.00% by mass of magnesium.

Calculate the mass of aluminium in this sample.

mass of aluminium =_........

Figure 5 shows a graph of the relative strength of aluminium-magnesium alloys when the percentage by mass of magnesium in the alloy is changed.

percentage by mass of magnesium in alloy

Figure 5

Describe what Figure 5 shows about the relative strength of these alloys when the percentage by mass of magnesium changes.

Determine, using Figure 5, the percentage by mass of aluminium in an aluminium‑magnesium alloy with a relative strength of 103.

percentage by mass of aluminium =_........

Metal objects can be electroplated with gold.

Give two reasons why metal objects are electroplated with gold.

This question is about electrolysis.

A sample of molten potassium bromide is electrolysed.

What are the two products formed?

Zinc chloride and zinc carbonate contain ions.

Zinc chloride mixed with water can be electrolysed. Zinc carbonate mixed with water cannot be electrolysed.

Explain this difference.

In the electrolysis of sodium chloride solution, bubbles of a colourless gas form at the cathode. This gas, when mixed with air, burns with a squeaky pop.

Identify this gas.

Explain how this gas is formed at the cathode.

A solution of copper sulfate in a beaker is electrolysed using copper electrodes.

Draw a labelled diagram to show how this experiment would be set up.

The beaker has been drawn for you.

During the electrolysis, the anode gets smaller, the cathode gets larger and the solution remains the same shade of blue.

Give the reason for each of these observations.

the anode gets smaller_........

the cathode gets larger_........

the solution remains the same shade of blue_........

Copper carbonate reacts with dilute nitric acid.

During the reaction the copper carbonate powder completely disappears.

State what can be deduced about the amount of acid used.

During the reaction, the pH of the mixture changed from 2 to 6.

By what factor has the concentration of the hydrogen ions in the mixture changed?

Using different reactants, a solution of copper sulfate was prepared.

Describe what should be done to obtain copper sulfate crystals from this copper sulfate solution.

When chloride ions are added to a pale blue solution containing copper ions, the mixture turns yellow.

This is a reversible reaction.

pale blue solution + chloride ions yellow solution + water

What effect does the removal of chloride ions have on the colour of the yellow mixture?

Hydrated copper sulfate has the formula CuSO₄.5H₂O. The formula tells us that each mole of copper sulfate contains 5 moles of water.

A sample of CuSO₄.5H₂O was heated gently until all the water was removed to form anhydrous copper sulfate, CuSO₄.

The mass of water formed was 4.5 g.

Calculate the mass of hydrated copper sulfate that was heated.

(relative atomic masses: H = 1.0, O = 16.0; relative formula mass: CuSO₄.5H₂O = 249.5)

mass of CuSO₄.5H₂O =_........

The order of reactivity of copper, magnesium and zinc can be determined by the displacement reactions between these metals and solutions of their salts.

You are provided with

• samples of the three metals

• solutions of copper sulfate, magnesium sulfate and zinc sulfate.

Describe the experiments that can be done to determine the order of reactivity of these metals by displacement reactions.

Metals can be extracted from ores found in the Earth’s crust.

Explain why aluminium cannot be extracted from its ore by heating with carbon but can be extracted by electrolysis.

Titanium is extracted from its ore in several stages.

In the first stage, titanium chloride is formed as a gas.

The gas is cooled to form liquid titanium chloride containing dissolved impurities.

Suggest how pure titanium chloride could be separated from the impurities.

In another stage, the pure titanium chloride, TiCl₄, is reacted with 500 moles of magnesium, an excess.

Calculate the number of moles in 45 000 grams of titanium chloride.

(relative atomic masses: C l = 35.5, Ti = 48.0)

number of moles titanium chloride =_........

Show that the 500 moles of magnesium added is an excess.

After this reaction, there is a mixture of the solids magnesium, titanium and magnesium chloride.

Titanium does not react with dilute hydrochloric acid.

Suggest a simple method to separate titanium from the mixture.

Hydrogen-oxygen fuel cells, rather than chemical cells, can be used to power some vehicles.

Give one advantage of using a hydrogen-oxygen fuel cell, rather than using a chemical cell, to power a vehicle.

Complete the half-equation for the reaction taking place at one of the electrodes in a hydrogen-oxygen fuel cell.

Calculate the volume of 48 g of oxygen at room temperature and pressure.

(relative atomic mass: O = 16, 1 mol of gas occupies 24 dm³ at room temperature and pressure)

volume of oxygen =_........

*(d) The hydrogen used in a hydrogen-oxygen fuel cell can be produced from methanol, CH₃OH.

In this reaction the forward reaction is endothermic and heat energy is taken in from the surroundings. The conditions used for this reaction are

• a nickel catalyst

• a temperature of 220 °C

Explain, in terms of their effects on the rate of attainment of equilibrium and the equilibrium yield of hydrogen, why the reaction is carried out using a catalyst at 220 °C rather than without a catalyst at a lower temperature.

An ion of element X can be represented as

This ion of element X has 54 electrons.

Calculate the number of protons and the number of neutrons in this ion.

A sample of silicon contains isotopes.

State, in terms of subatomic particles, how atoms of these isotopes are the same.

This sample of silicon contains three isotopes.

92% of the atoms are silicon-28 5% of the atoms are silicon-29 3% of the atoms are silicon-30

Calculate the relative atomic mass of silicon in this sample.

relative atomic mass =_........

*(c) Figure 6 shows some properties of three substances, A, B and C.

Deduce, using the information in Figure 6, the structure and bonding of substances A, B and C, explaining their properties in terms of their structure and bonding.

A sample of solid potassium hydroxide contained soluble, unreactive impurities.

A student tried to find the mass of potassium hydroxide in the sample, using the following method.

step 1 measure the mass of the sample of impure potassium hydroxide

step 2dissolve the sample in 250 cm³ of water in a beaker

step 3take a 25 cm³ sample of the potassium hydroxide solution using a measuring cylinder and pour into a conical flask

step 4 add 3 drops of indicator to the solution

step 5 put the conical flask on a white tile

step 6 using a burette, add dilute sulfuric acid of known concentration drop by drop to the solution, while swirling the flask

step 7 continue adding the sulfuric acid until the colour of the solution changes

step 8 record the volume of sulfuric acid added

step 9 use this result to calculate the mass of pure potassium hydroxide in the sample.

Suggest three ways to improve this method to obtain a more accurate mass of pure potassium hydroxide.

The indicator used was phenolphthalein.

Which row shows the colour change that would be seen in this titration?

Another student carried out the titration accurately.

12.15 cm³ of dilute sulfuric acid with a concentration of 0.140 mol dm^–3 reacted completely with 25.00 cm³ of potassium hydroxide solution.

Calculate the concentration of this potassium hydroxide solution.

concentration of potassium hydroxide solution =_........ mol dm

A different solution of potassium hydroxide had a concentration of 0.175 mol dm^–3.

This potassium hydroxide solution was made by dissolving 2.56 g of impure potassium hydroxide to form 250 cm³ of solution.

Calculate the percentage by mass of potassium hydroxide in the impure potassium hydroxide.

(relative formula mass: KOH = 56.0)

percentage by mass of potassium hydroxide =_........