Energy changes in reactions - end of topic test

Which of the following processes is always exothermic?

• Photosynthesis

• Boiling

• Combustion

• Thermal decomposition

Which of the following processes is always endothermic?

• Combustion

• Respiration

• Photosynthesis

• Freezing

If a reaction is endothermic what might you see?

• It might boil

• It might freeze

• It might give off sparks

• The test tube would feel warm

Why are some reactions exothermic?

• It doesn't take in any energy to break the bonds

• It doesn't give out any energy when you make bonds

• More energy is taken in to break bonds than given out to make bonds

• More energy is given out to make bonds than is taken in to break bonds

Describe the ΔH value for all exothermic reactions:

• Large

• Small

• Positive

• Negative

What is meant by activation energy?

• The energy that allows you to be active in the morning when you eat breakfast

• The energy needed to 'activate' bonds in a molecule

• The minimum energy needed for a reaction to occur

• The energy given off when an exothermic reaction happens

Tick all that apply:

When sodium is reacted with water, which of the following are true?

• The reaction is exothermic

• There is a purple flame

• The sodium melts into a ball

• There is effervescence of oxygen gas

Tick all that apply:

When calcium carbonate undergoes a thermal decomposition reaction, which of the following are true?

• The equation is: CaCO₃ --> CaO + CO₂

• The reaction is endothermic because heat energy must be put in

• The ΔH value for the reaction is negative

• If I start with 100g of CaCO₃, I will make 44g of CO₂ and 56g of CaO

Tick all that apply:

When respiration occurs, which of the following are true?

• The equation for the reaction is: 6CO₂ + 6H₂O --> C₆H₁₂O₆ + 6O₂

• The reaction releases heat energy

• It is the same reaction as the complete combustion of glucose

• ΔH is negative

Which letter shows the products?

• A

• B

• C

• D

• E