Topic 5 Energetics Pre-Study

When sodium is added to water it reacts violently and melts.

Which answer describes the type of reaction and how the temperature of the water changes during the reaction?

• The type of reaction is endothermic and the temperature of the water decreases

• The type of reaction is endothermic and the temperature of the water increases

• The type of reaction is exothermic and the temperature of the water decreases

• The type of reaction is exothermic and the temperature of the water increases

Hand warmers keep hands warm on a cold day.

Which statement describes how hand warmers work?

• An endothermic process occurs in which chemical energy is transformed into thermal energy

• An endothermic process occurs in which thermal energy is transformed into chemical energy

• An exothermic process occurs in which chemical energy is transformed into thermal energy

• An exothermic process occurs in which thermal energy is transformed into chemical energy

Which one of the following physical changes is exothermic?

• Melting

• Condensing

• Boiling

• Sublimation

Which statements are correct?

• Bond breaking is an endothermic process

• Bond breaking is an exothermic process

• Bond making is an endothermic process

• Bond making is an exothermic process

The graph represents the energy change associated with the reaction of a halogen with hydrogen.

Which type of reaction does the energy graph represent?

• Exothermic

• Endothermic

Which statement about chemical reactions is correct?

• Endothermic reactions result in a temperature decrease

• Endothermic reactions result in a temperature increase

• Exothermic rections always produce a large temperature rise

• Exothermic rections always produce a small temperature rise

What happens when an acid reacts with an alkali?

• Neutralisation takes place and the temperature falls

• Neutralisation takes place and the temperature rises

• Reduction takes place and the temperature falls

• Reduction takes place and the temperature rises

When sodium hydroxide and hydrochloric acid are mixed they react immediately. The graph shows how the temperature of the mixture changes over time.

Which type of chemical reaction takes place?

• Both exothermic and endothermic

• Endothermic

• Exothermic

• Neither

Which one of the following reactions is not exothermic?

• Combustion of methane

• Oxidation of magnesium

• Thermal decomposition of calcium carbonate

• Displacement of copper ions from solution by zinc metal

A diagram for the energy change during an exothermic reaction is shown.

For which reactions would this be an appropriate diagram?

1. CH₄ + 2O₂ → CO₂ + 2H₂O

2. 2H₂ + O₂ → 2H₂O

3. C + O₂ → CO₂

• 1 and 2

• 2 and 3

• 1 and 3

• All