Formulations

Screenwash is a mixture designed to keep car windscreens clean.

The components in screenwash include glycerol, methanol and water.

Screenwash is made by mixing the components in carefully measured quantities so that the product has the required properties.

What name is given to this type of mixture?

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Glycerol has the formula C₃H₈O₃

How many atoms are there in one molecule of glycerol?

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Incomplete combustion happens when glycerol burns in limited oxygen.

Incomplete combustion produces carbon monoxide gas.

Why can the production of carbon monoxide gas be a problem?

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Complete combustion happens when methanol (CH₄O) burns in excess oxygen.

Balance the equation for the reaction.

Methanol can be produced by the reaction of carbon dioxide with hydrogen.

Describe the test for hydrogen gas.

Give the result of the test.

Carbon dioxide is a greenhouse gas.

An increase in greenhouse gases in the atmosphere has led to an increase in average global temperature.

The increase in average global temperature has caused global climate change.

Give two effects of global climate change.

Anhydrous cobalt chloride can be used to test for water.

The word equation for the reaction is:

anhydrous cobalt chloride + water hydrated cobalt chloride (blue) (pink)

Suggest one observation that could be made when water is added to anhydrous cobalt chloride.

The reaction between anhydrous cobalt chloride and water is exothermic.

What type of reaction is the reverse reaction?

This question is about methanol.

Methanol is used in screenwash.

Screenwash is used to keep car windscreens clean.

Screenwash is a formulation.

Define the term ‘formulation’.

Carbon monoxide and hydrogen are used to produce methanol.

The conditions used in the production of methanol are:

• high temperature

• high pressure

• a catalyst.

The equation for the reaction is:

91 kJ/mol of energy is transferred during the exothermic forward reaction.

How much energy is transferred when methanol is decomposed into carbon monoxide and hydrogen?

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A scientist developed a principle to predict the effect of changing conditions on a system at equilibrium.

What was the name of the scientist?

What is the effect of increasing the temperature on the proportion of methanol in the equilibrium mixture?

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What is the effect of using a catalyst on the proportion of methanol in the equilibrium mixture?

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Explain the effect of increasing the pressure on the proportion of methanol in the equilibrium mixture.

Explain the effect of using a catalyst on the rate of production of methanol.

The catalyst allows the reaction to take place at a lower temperature.

Explain one advantage of using a lower temperature in the production of methanol.

Do not refer to the position of equilibrium in your answer.

Methanol (CH₃OH) can also be produced by reacting carbon dioxide with hydrogen.

Water is the other product of the reaction.

Write a balanced equation for the reaction.

Printer ink is a mixture of chemicals.

What is the name given to a mixture that has been designed as a useful product?

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A student used chromatography to investigate the colours in a printer ink.

Figure 2 shows the chromatogram.

The student used a ruler for the start line.

What would the student have used to draw the start line?

Give one reason for your answer.

Determine the R_f value of the red colour.

Use the equation:

Distance moved by red colour

Distance moved by solvent

Table 2 shows the R_f values of four blue colours.

The student determined that the R_f value of the blue colour in the printer ink was 0.86

Suggest which blue colour was used in the printer ink.

Give one reason for your answer.

Crude oil is a mixture of many different compounds.

Give two reasons why crude oil is not a formulation.

Describe how crude oil is separated into fractions.

The fractions from crude oil contain alkanes. Explain why alkanes are cracked.

Cracking produces a mixture of products.

An equation for cracking decane (C₁₀H₂₂) is:

Describe a test to identify the gas produced in the reaction.

Alkenes are produced in cracking. The general formula for the homologous series of alkenes is C_nH_2n Which formula represents an alkene? Tick (✓) one box.

This question is about ammonia and its compounds.

A student heated a sample of ammonium chloride.

The equation for the reaction is:

One product is ammonia.

What is the name of the product with the formula HC l ?

Ammonia is a gas.

What is the state symbol for ammonia?

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How does the equation show that the reaction is reversible?

The industrial process to produce ammonia uses a catalyst.

Figure 5 shows the reaction profile for the reaction with and without a catalyst.

Which letter represents the activation energy for the reaction with a catalyst?

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Give one reason why using a catalyst reduces costs.

Do not answer in terms of activation energy.

Ammonia is in a mixture that is used as a household cleaner.

What is a mixture that has been designed as a useful product called?

This question is about mixtures.

Which substance is a mixture? Tick (✓) one box.

Food colourings are often mixtures of dyes. What name is given to mixtures that are designed as useful products?

A student investigated a purple food colouring, Y, using chromatography. The student compares Y with dyes A, B and C.

Figure 8 shows the apparatus used.

Chromatography involves a stationary phase and a mobile phase.

Draw one line from each phase to what is used for that phase. Use Figure 8. Phase What is used

Figure 9 shows the student’s results.

What three conclusions can you make about the dyes in food colouring Y ?

In a different experiment a student recorded these results: Distance moved by dye G = 60 mm Distance moved by solvent = 80 mm Calculate the R_f value of dye G.

Concrete contains cement, water, sand and small stones.

Concrete is a mixture designed as a useful product.

What do we call a mixture which has been designed as a useful product?

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Concrete contains cement.

Cement is made by heating a mixture containing silicon dioxide (SiO₂).

Why does silicon dioxide have a very high melting point?

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Student A investigated how the mass of the small stones in concrete affects the strength of a concrete beam. All other variables were kept the same.

The student added weights until the concrete beam broke.

Figure 1 shows the apparatus Student A used.

Draw one line from each type of variable to the correct example of the variable.

Table 1 shows Student A ’s results.

Plot the data from Table 1 on Figure 2.

The first three points are plotted for you.

Draw the line of best fit.

What mass of small stones would be needed to make the strongest concrete?

Give a reason for your answer.

Use Figure 2.

Student B did a similar investigation.

Figure 3 shows Student B ’s results.

How could Student B improve their investigation?

Use Figure 2 and Figure 3.

This question is about chromatography of food colouring.

Food colouring is a formulation. What is a formulation?

Explain how paper chromatography separates the dyes in a food colouring. Do not give details of how to do the experiment.

Explain how the student could tell from the chromatogram that the food colouring contained more than one dye.

Explain how the student could use chromatography to identify unknown dyes in the food colouring.

What percentage of the Earth’s atmosphere is nitrogen?

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During the first billion years of the Earth’s existence the amount of nitrogen in the atmosphere increased.

Give one source of this nitrogen.

Nitrogen is used to make ammonia.

The word equation for the reaction is:

Write the correct symbol in the equation to show that it is a reversible reaction.

A reversible reaction can reach equilibrium.

Complete the sentence.

Equilibrium is reached when the forward reaction and the reverse reaction happen at

Fertilisers are formulations containing nitrogen.

What is a formulation?

Table 4 shows percentages of chemical elements in a fertiliser.

Draw the bar for potassium on Figure 8

Use the information in Table 4

A fertiliser contains 0.225 g of iron per 3.0 g of fertiliser.

Which calculation gives the percentage of iron in the fertiliser?

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Figure 9 shows the use of fertiliser in four different countries, A, B, C and D, in 2003 and 2015

A student said:

‘ much more fertiliser was used in 2015 than in 2003’

Is the student correct?

Use data from Figure 9 to justify your answer.

Fertilisers are formulations.

What is a formulation?

A bag of fertiliser contains 14.52 kg of ammonium nitrate (NH₄NO₃). Relative formula mass (M_r): NH₄NO₃ = 80 Calculate the number of moles of ammonium nitrate in the bag of fertiliser. Give your answer in standard form to 2 significant figures.

The fertiliser also contains potassium chloride. Explain why potassium chloride has a high melting point.