C3.2 Energetics

Question 1

What is exothermic reaction?

Answer 1

Gives out energy to the surroundings causing the temperature in the surroundings to rise.

Question 2

What is endothermic reaction?

Answer 2

Takes in energy from the surrounding causing the temperature of the surrounding to fall.

Question 3

What are examples of exothermic and endothermic reaction?

Answer 3

Exothermic - Combustion, Neutralisation , Heat Packs

Endothermic - Thermal Decomposition, Photosynthesis, cooler packs

Question 4

What is a reaction profile?

Answer 4

It is a chart that shows the energy involved.

Question 5

Definition of activation energy?

Answer 5

Activation energy is the minimum energy needed for a reaction to start.

Question 6

What is bond energy?

What reaction is bond breaking and bond making?

Answer 6

Bond energy is the amount of energy that must be transferred to break a mole of a particular covalent bond.
Bond breaking is endothermic
Bond making is exothermic

Question 7

What symbols does exothermic and endothermic present?

Answer 7

+ —> endothermic

- —> exothermic

Question 8

Two powders are soluble in water.
Describe a simple experiment you could carry out to see whether an exothermic change or an endothermic change happens when each powder dissolves in water.

Answer 8

Put some water into a beaker or insulated cup
Use a thermometer to measure the temperature of the water
Add some of the powder and stir it
Measure the new temperature
If the temperature goes up, the change is exothermic
If the temperature goes down, the change is endothermic

Question 9

One of these products produce a alkaline solution when it dissolves. Explain to precautions you could take to reduce the risk of harm from this hazard.

Answer 9

Avoid skin contact using gloves

Avoid eye contact using eye protection