C5 Chemical Energetics

The energy level diagram for the reaction between sodium hydrogen carbonate and dilute hydrochloric acid is shown.

Which row correctly describes the type of reaction and the energy of the reactants and products?

• A

• B

• C

• D

The energy level diagram for the reaction between magnesium and hydrochloric acid is shown.

Which statement about the reaction is not correct?

• Energy is given out during the reaction.

• The products are at a lower energy level than the reactants.

• The reaction is endothermic.

• The temperature increases during the reaction.

The energy level diagram shows the energy of the reactants and products in a chemical reaction.

Which row correctly describes the energy change and the type of reaction shown?

• A

• B

• C

• D

Which reaction is endothermic?

• acid neutralising alkali causing a temperature increase

• adding magnesium to hydrochloric acid

• calcium carbonate decomposing when heated

• combustion of fossil fuels

Solid hydrated sodium carbonate was added to solid citric acid.

The mixture was stirred and the temperature recorded every 10 seconds.

The results are shown on the graph.

Which row describes the reaction?

• A

• B

• C

• D

Which row correctly describes whether the reaction is exothermic or endothermic?

• A

• B

• C

• D

A metal reacts with an aqueous solution.

The graph shows the temperature before, during and after the reaction.

Which row describes the reaction?

• A

• B

• C

• D

The diagrams show four chemical reactions. Which reaction is endothermic?

• A

• B

• C

• D

Limestone can be changed into slaked lime in two chemical reactions.

1 When limestone, CaCO3, is heated it decomposes into lime, CaO.

2 Water is slowly dripped onto the cooled lime. The lime appears to expand and steam is produced. Slaked lime, Ca(OH)2, is formed.

Which row shows the correct description of each of the chemical reactions?

• A

• B

• C

• D

Which statements about exothermic and endothermic reactions are correct?

1. 1. During an exothermic reaction, heat is given out.

2. 2. The temperature of an endothermic reaction goes up because heat is taken in.

3. 3. Burning methane in the air is an exothermic reaction.

• 1, 2

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only