OCR GCSE Chemistry B (21st Century) Paper 1 November 2020 question paper

Drinking cups can be made from poly(propene) or aluminium.

Poly(propene) is made from propene. Propene has the structural formula CH₃CH = CH₂.

Which is the correct displayed formula for propene?

Complete Fig. 1.1 to show the repeating unit of poly(propene).

Use one term from the list.

Aluminium has a metallic structure.

Label the metallic structure shown in Fig. 1.2 by completing the boxes.

Complete the sentence to explain why aluminium conducts electricity.

Aluminium conducts electricity because it contains........

which can move.

Apart from cost, suggest one advantage of poly(propene) plastic drinking cups instead of aluminium metal drinking cups.

Using Fig. 2.1, what was the temperature in 1910?

Using Fig. 2.1, calculate the temperature rise between 1980 and 2000.

Using Fig. 2.1, which two time periods show the greatest temperature rises?

Tick (✓) two boxes.

Some scientists believe that world temperatures have increased due to increased amounts of greenhouse gases in the air.

How do greenhouse gases increase world temperatures?

Tick (✓) one box.

Carbon dioxide is a greenhouse gas.

Draw lines to connect each question with one correct answer.

Ethene is a gas.

The formula of ethene is C₂H₄.

Name the two elements in ethene.

What is the empirical formula of ethene?

CH CH₂ C₂H₂ C₂H₄

Which homologous series does ethene belong to?

acids alcohols alkanes alkenes

Ethene reacts with bromine water to make dibromoethane.

Complete the sentences below to describe this reaction.

Use words from the list.

Each word can be used once, more than once or not at all.

addition colourless single

displacement oxidised double

This type of reaction is called........

The bromine water becomes........

Ethene reacts because it contains a........ bond.

Diamond and graphite are allotropes of carbon. They are both giant structures.

Fig. 4.1 shows models of diamond and graphite:

Diamond Graphite

Fig. 4.1

What do the black dots in Fig. 4.1 represent?

Name the type of bond that is represented by the solid black lines in Fig. 4.1.

Fig. 4.2 shows a model of sodium chloride, which has a giant ionic lattice structure.

Describe one similarity and one difference between the properties of sodium chloride and graphite.

Similarity........

Difference........

Lithium-ion batteries are used in phones, tablets and electric cars.

Lithium reacts with chlorine and with bromine.

Lithium is in Group 1. Chlorine and bromine are in Group 17.

Draw lines to connect each element with one correct property.

14 g of lithium reacts with 71 g of chlorine.

What mass of chlorine reacts with 5.6 g of lithium?

Jack reacts lithium with chlorine. He then reacts lithium with bromine.

Describe how the rates of these two reactions are different.

The iron nail in Tube B rusts much more slowly than the iron nail in Tube A.

Explain why.

Explain your answer to (a)(ii).

Mia collects the rust. She dissolves the rust in hydrochloric acid and adds some sodium hydroxide solution.

She sees a brown precipitate.

What is the name of this brown precipitate?

Tick (✓) one box.

Mia now reacts an iron nail with hydrochloric acid.

Write a word equation for this reaction.

Amir has a sample of a salt, Salt A, that is used as a fertiliser.

He does some tests to find out which elements are in the salt.

Amir finds that Salt A contains positive potassium ions.

Which colour flame does Amir see when he does a flame test?

green lilac red yellow

Potassium is an element. It is an essential nutrient for plants.

Name one other element that is an essential nutrient for plants.

Amir thinks Salt A is potassium sulfate.

Potassium sulfate contains K⁺ ions and SO₄^2– ions.

What is the chemical formula of potassium sulfate?

Amir tests Salt A to check it is potassium sulfate.

He dissolves some of Salt A in water and adds barium chloride solution.

Barium sulfate is formed.

Describe the colour and state of the barium sulfate formed.

Complete the word equation for the reaction.

Amir tests another unknown salt, Salt B, by looking at its emission spectrum.

Some emission spectra are shown in Fig. 7.1:

Using Fig. 7.1, name the metal ion in Salt B.

Convert 400 nm to metres.

Give your answer in standard form.

1 nm = 1 × 10^–9 m

Elements can be identified using flame tests or by comparing emission spectra.

Amir uses the internet to compare each method:

Amir is given 0.01 g of a compound to analyse.

Amir decides to use a flame test rather than comparing emission spectra.

Give one advantage and one disadvantage of using a flame test rather than comparing emission spectra.

Advantage........

Disadvantage........

Titanium is used for hip replacements.

Titanium, Ti, can be made from titanium oxide by two methods.

Method 1 uses magnesium which reacts with titanium oxide:

Use the symbol equation in Method 1 to help you.

Magnesium is more reactive than titanium oxide / titanium / magnesium oxide.

Magnesium reduces titanium oxide / titanium / magnesium oxide

to titanium oxide / titanium / magnesium oxide.

Calculate the relative formula mass of magnesium oxide (MgO).

Use the Periodic Table.

Calculate the percentage of magnesium in magnesium oxide (MgO).

Use relative formula mass of magnesium = 24.

Method 2 uses electrolysis to make titanium:

Method 2 has a higher atom economy than Method 1.

Some relative formula masses are given in the table.

Calculate the atom economy for Method 2.

Use the data from the table.

Give your answer to 1 decimal place.

Look at the equations again for Method 1 and Method 2.

Explain why Method 2 has a higher atom economy than Method 1.

Magnesium oxide (MgO) is formed in Method 1.

Fig. 8.1 shows the ‘dot and cross’ diagrams for a magnesium (Mg) atom and an oxygen (O) atom.

Complete Fig. 8.2 to show the ‘dot and cross’ diagrams for an Mg²⁺ ion and an O^2– ion.

Magnesium oxide can be formed by burning magnesium in oxygen.

Complete the balanced symbol equation for this reaction.

Ammonia is used to make synthetic fertilisers.

Ammonia is manufactured in the Haber process.

Which statements about this reaction are true and which are false?

Tick (✓) one box in each row.

Sundip makes ammonium sulfate from a solution of ammonia in the laboratory. The method is shown below but is not in the correct order.

Write a number from 1–6 in each box to give the correct order for the steps of the method.

Sundip makes 9.9 g of ammonium sulfate.

The maximum mass of ammonium sulfate she could have made is 13.2 g.

Calculate the percentage yield.

Layla does a titration to find out the concentration of some sodium hydroxide solution. She reacts hydrochloric acid with the sodium hydroxide solution.

Layla says, ‘The titration uses a neutralisation reaction.’

Define a neutralisation reaction.

This is Layla’s incomplete method for the titration:

• Put the hydrochloric acid in a burette.

• Put the sodium hydroxide solution in a flask.

• Add the hydrochloric acid to the sodium hydroxide solution.

• Stop adding the hydrochloric acid when the sodium hydroxide solution is neutralised.

Layla needs to add another substance to the flask so that she knows when to stop adding the hydrochloric acid.

Which substance does Layla need to add, and what will she see?

Layla needs to add........

Layla will see........

Layla titrates the hydrochloric acid into a flask from a burette. She wants to make sure her final burette reading is as accurate as possible.

Describe one thing Layla can do to make her reading as accurate as possible.

Layla’s results for her rough titration are shown in Table 10.1.

Complete Table 10.1 by calculating the volume for the rough titration.

Layla's repeat readings for her careful titrations are shown in Table 10.2.

Layla calculates that the mean titration volume is 24.60 cm³.

Explain why Layla is correct.

Use the information in Table 10.2 and a calculation in your answer.

Beth has some tablets that react by fizzing, and then dissolving, when water is added.

Beth puts a whole tablet into Tube A, and a broken-up tablet into Tube B.

Whole tablet
Broken-up tablet

Fig. 11.1

Beth wants to measure the rate of the two reactions. This is Beth’s method:

• Add the same volume of cold water to each test tube at the same time.

• Start a stopwatch.

When should Beth stop the stopwatch?

Tick (✓) one box.

Which type of tablet, whole or broken-up, will dissolve more quickly?

Explain your answer.

Use ideas from the particle model in your answer.

Suggest one reason why the reactions are much faster using hot water.

Fig. 11.2 shows how the mass of Tube A and its contents changes over time when cold water is added.

Using Fig. 11.2, explain why the mass of Tube A and its contents decreases during the reaction.

The rate of the reaction decreases with time.

Describe how Fig. 11.2 shows this.

Explain why the rate of reaction decreases with time.