Reversible reactions

Nitrogen is a gas found in the Earth’s atmosphere.

The table shows the percentages of different gases found in the Earth’s atmosphere.

Calculate the percentage of nitrogen in the Earth’s atmosphere.

Nitrogen reacts with hydrogen to form ammonia.

The word equation for the reaction is:

Describe how the word equation shows that the reaction is reversible.

The word equation for the forward reaction is:

Write the word equation for the backward reaction.

This table shows the percentage of ammonia produced in the reaction at different pressures.

Plot the data from the table on the graph. The first two points are already plotted.

Draw the curve of best fit.

Oxides of nitrogen released from cars cause acid rain.

Oxides of nitrogen responsible for acid rain are given the formula NO_x.

What is the value of x in nitrogen dioxide?

Normal rain water is slightly acidic.

Describe a test and its result to show that acid rain is more acidic than normal rain water.

Test........

Result........

The reversible reaction.

The reaction of a very reactive metal.

The reaction of a green gas.

The reaction where a more reactive metal displaces a less reactive metal.

The reaction where a metal is extracted using electrolysis.

When a solution of yellow Fe³⁺(aq) ions is mixed with a solution of colourless SCN^–(aq) ions they 16 react to form a solution of red FeSCN²⁺(aq) ions.

This is an example of a dynamic equilibrium.

Complete the equation for this reaction.

Plot the results from the table on the graph. Two points have already been plotted for

you.

Draw a line of best fit.

What is the time it takes for the reaction to reach equilibrium?

Give a reason for your answer.

Time to reach equilibrium =........ seconds

A student increases the concentration of SCN – (aq) ions in the mixture. (c)

The mixture turns darker red.

Use Le Chatelier’s principle to explain the change in colour.

The student thinks that the forward reaction shown in (a) for the equilibrium is exothermic

Describe what the student should do to the equilibrium mixture to show that the forward reaction is exothermic.

Predict the student’s observations.

Nitrogen, N₂, reacts with hydrogen, H₂, to make ammonia, NH₃.

What is the name of this type of reaction?

A Combustion

B Electrolysis

C Neutralisation

D Reversible

A student investigates heating hydrated copper(II) sulfate, CuSO₄.5H₂O.

The diagram shows the experiment they do.

The student:

• Measures the mass of a boiling tube.

• Puts about 5 g of hydrated copper(II) sulfate in the boiling tube and measures the mass.

• Gently heats the boiling tube for one minute.

• Lets the boiling tube cool down and measures the mass.

During the experiment the hydrated copper(II) sulfate turns from blue to white and water vapour is produced.

Look at the student’s results.

Calculate the mass of water produced in the experiment.

The student expected a greater mass of water to be produced.

How could they improve the experiment so a greater mass of water vapour is produced?

Complete and balance the symbol equation.

The student adds a few drops of water to a boiling tube containing some of the white solid.

Describe what the student observes happening to the white solid.

Give a reason for your answer.

Observation........

Reason........

As water reacts with the white solid, the temperature of the boiling tube increases.

What name is given to this type of reaction where heat is transferred to the surroundings?

The reaction between sulfur dioxide and oxygen is reversible.

In a closed system the reaction between sulfur dioxide and oxygen reaches a dynamic equilibrium.

Use a symbol from the list to complete the sentence.

At equilibrium, the rate of the forward reaction is …….... the rate of the reverse reaction.

What is meant by the term reversible reaction ?

Name one source of sulfur dioxide in the atmosphere.

Describe two problems caused by the release of sulfur dioxide into the atmosphere.

The table shows some relative atomic masses.

Calculate the percentage, by mass, of oxygen in SO₂.

Give your answer to 1 decimal place.

The amount of sulfur dioxide released in the UK is decreasing.

This graph shows how it has decreased since 1970.

How much did the sulfur dioxide decrease between 1975 and 2015?

Sulfur dioxide decrease =........ kilotonnes