OCR GCSE Chemistry B (21st Century) Paper 1 November 2021 question paper

In the early nineteenth century, a chemist called Dobereiner found sets of three elements with similar properties.

Table 1.1 shows an example:

State the Group number of lithium, sodium and potassium in the modern Periodic Table.

Which statements about lithium, sodium and potassium are true and which are false ?

Tick (✓) one box in each row.

The elements nitrogen, phosphorus and arsenic have similar properties.

Complete Table 1.2 by adding the symbols for these three elements.

Dobereiner called his sets of three elements ‘triads’. He had this idea:

‘The relative atomic mass of element 2 is approximately equal to the mean of the other two elements.’

Do the elements in Table 1.2 fit Dobereiner’s idea?

Use a calculation to help explain your answer.

Mendeleev arranged the elements in order of their relative atomic masses.

Mendeleev’s work was peer reviewed.

Describe the peer review process.

Water evaporates from lakes and oceans. It forms clouds of gaseous water.

In the right conditions the water falls as rain, as shown by the equation:

Which two processes does this equation show?

Tick (✓) two boxes.

Fig. 2.1 represents the three states of matter: solid, liquid and gas.

Write the word for the correct state under each model.

Fig. 2.1

Fig. 2.2 shows a molecule of oxygen, O₂.

Fig. 2.2

Draw a similar diagram to show a molecule of water, H₂O.

The table shows the percentage of nitrogen and carbon dioxide in air:

Calculate how many times more nitrogen there is than carbon dioxide in air.

........ times more nitrogen than carbon dioxide

Oxygen is 21% of air.

Plot the data for oxygen on the bar chart.

Draw lines to connect each gas with its correct property.

Relights a glowing splint.

Plastic bags are made of poly(ethene).

Poly(ethene) is made by polymerisation of ethene.

Complete the diagram to show the polymerisation of ethene, C₂H₄.

Ethene, C₂H₄, is made by cracking molecules such as decane, C₁₀H₂₂.

Complete the symbol equation for this reaction.

The table shows the energy required to make 1000 poly(ethene) bags and transport them to shops:

Calculate the total energy required per bag.

Use data from the table.

Calculate the percentage of the energy in the table required to make the raw materials for 1000 bags.

Give your answer to 2 significant figures.

Some plastic materials are described as ‘biodegradable’.

What does ‘biodegradable’ mean?

Amaya is given some coloured sweets.

She uses chromatography to find out the number of dyes in each sweet.

Amaya starts by drawing a line on a piece of filter paper using ink.

Describe one way in which Amaya can improve this part of her method.

Give one reason for your answer to (a)(i).

Sundip repeats the experiment, improving on Amaya’s method.

Her results are shown in the chromatogram:

Each sweet contains a mixture of dyes.

How many different dyes are there in all of the sweets that Sundip has used?

Use the chromatogram.

Which dye is the least soluble in the solvent?

Give one reason for your answer to (b)(ii).

R_f values can be calculated using this equation:

Which dye has the largest R_f value?

Ali has a mixture of carbon and copper sulfate crystals. Carbon is insoluble in water.

Complete the list to show the correct order of methods he needs to obtain pure copper sulfate crystals from the mixture.

Use the words.

You can use each word once, more than once, or not at all.

Crystallization Dissolving Distillation Heating

1........

2 Filtration

3........

4........

Chemists use models to describe things that are too small to be seen.

Fig. 5.1 shows an atomic model proposed by a scientist over 100 years ago:

Which scientist suggested the atomic model in Fig. 5.1 ?

Dalton Thomson Rutherford Bohr

The modern model of the atom is different from the model in Fig. 5.1.

Complete the sentences about the modern model of the atom.

Use the words.

You can use each word once, more than once, or not at all.

electrons ions neutrons nucleus protons

The centre of the atom is called the........

This is made up of positively charged........ and

neutral........

The........ are negatively charged.

In a neutral atom, there are equal numbers of........

and........

Fig. 5.2 shows a model of an ethanol molecule and a methane molecule:

The formula of methane is CH₄.

What is the formula of ethanol?

Use Fig. 5.2 to help you.

Which two statements do the models in Fig. 5.2 accurately show?

Tick (✓) two boxes.

Fig. 5.3 shows models of four types of giant structure.

Which two structures are compounds?

A B C D

Which structure conducts electricity when it is solid?

A B C D

Which two structures contain ions?

A B C D

Blue copper sulfate crystals turn white when heated:

• Kai weighs out five different samples of ‘blue copper sulfate’.

• He puts each sample in a test tube.

• He heats each test tube.

• He weighs each test tube and its contents after heating.

• He then calculates the mass of ‘white copper sulfate’.

Fig. 6.1 shows a graph of his results:

Mass of ‘blue copper sulfate’ at start (g)

Fig. 6.1

One result does not fit the pattern.

Kai thinks he made a mistake when he was heating the ‘blue copper sulfate’ for this result.

Suggest the mistake Kai made.

Calculate the mass of ‘white copper sulfate’ that is made when 2.0 g of ‘blue copper sulfate’ is heated.

Use the equation: mass of ‘white copper sulfate’ × 1.5625 = mass of ‘blue copper sulfate’

Jane and Kai discuss the results:

Explain why Jane and Kai are both correct.

Jane........

Kai........

100 g of ‘blue copper sulfate’ gives 64 g of ‘white copper sulfate’.

Calculate the mass of water that is formed.

Jane tests whether this reaction is reversible:

She adds water to ‘white copper sulfate’ in a test tube. The solid turns blue and the test tube gets hot.

Does her observation show that the reaction is reversible?

Explain your answer.

What name is given to a reaction that gives out heat?

Draw one line to show the energy level of ‘blue copper sulfate’ on the reaction profile in Fig. 6.2.

Label your line ‘blue copper sulfate’.

Crude oil contains many compounds that are used as fuels.

The table shows some of these compounds:

Which word describes crude oil?

Chemical Compound Element Mixture

Name the two compounds in the table that are gases at 25 °C.

Explain your answer to (b)(i).

Calculate the relative formula mass of methane.

Use the Data Sheet.

Describe the relationship between relative formula mass and boiling point for the compounds in the table.

Benzene has six carbon atoms but is not an alkane.

Alkanes have the general formula C_nH_2n+2.

Give the formula of the alkane with six carbon atoms.

The graph shows the boiling point and the number of carbon atoms for some alkanes.

Hexadecane has 16 carbon atoms. The boiling point of hexadecane is 287 °C.

Plot the point for hexadecane on the graph.

Draw a line of best fit.

Estimate the boiling point of the alkane with the formula C₁₂H₂₆.

Show your working on the graph.

Fractional distillation is used to separate the compounds in crude oil.

Which property is used to separate compounds in fractional distillation?

Tick (✓) one box.

The formula for butane is C₄H₁₀.

Draw the displayed formula for butane.

What is the simplest ratio of carbon atoms to hydrogen atoms in butane?

Ratio of carbon atoms: hydrogen atoms =........:........

State the empirical formula of butane.

Chlorine is used to make water safe to drink.

How does chlorine make water safe to drink?

James has a solution of chlorine in water.

He tests the solution with blue litmus paper.

State two colour changes that James will see.

Mia adds a solution of chlorine to a solution of sodium bromide.

This is the equation for the reaction that happens:

The solution changes colour.

State the colour of the solution at the end of the experiment.

What causes the colour change?

Potassium reacts with chlorine. Sodium also reacts with chlorine.

Is the reaction of sodium with chlorine faster or slower than the reaction of potassium with chlorine?

Explain why the rate of reaction is different.

Calcium also reacts with chlorine. Calcium forms Ca²⁺ ions and chlorine forms Cl^– ions.

What is the correct formula of calcium chloride?

CaCl Ca₂Cl₂ CaCl₂ ClCa₂ ClCa

The element astatine, At, is below iodine in Group 7 of the Periodic Table.

Which two properties of astatine are correct?

Tick (✓) two boxes.

Alex reacts zinc with excess hydrochloric acid.

Fig. 9.1 shows the apparatus Alex uses:

Alex measures the volume of gas made at the start and then again after every minute for 7 minutes.

Fig. 9.2 shows a graph of his results:

What is the gradient of the curve at 5 minutes?

Gradient =........ cm³ / minute

What happens to the reaction after 5 minutes?

Which value is a correct estimate for the rate at which the reaction starts?

Use Fig. 9.2.

Tick (✓) one box.

2.0 g of zinc makes a total of 800 cm³ of gas. (c)

Calculate the mass of zinc Alex used in his experiment.

Use the total volume of gas produced in Fig. 9.2.

Alex repeats the experiment with different metals and excess acid. He wants to compare the rate of reaction for the different metals.

State two factors that he should control in these experiments to get valid results.

Fig. 9.3 shows Alex’s results for zinc, magnesium and iron:

Which metal makes each curve in Fig. 9.3 ?

Curve A........

Curve B........

Curve C........