Physical Chemistry

Question 1

What is exothermic?

Answer 1

An exothermic reaction is one where there has been more energy released from forming new bonds than there was needed to break them. This means that the surroundings of the reaction increase in temperature.

Question 2

What is endothermic?

Answer 2

A reaction that takes energy from the surroundings causing the temperature to drop. This is because the energy needed to break old bonds is greater than the energy released by forming new bonds.

Question 3

What are two ways of measuring the rate of reaction?

Answer 3

• The rate at which the products are being produced (e.g. use a syringe if gas is produced)
• The rate at which the reactants are being used up.

Question 4

What are the 5 ways that the speed of reaction can be increased?

Answer 4

1. Increasing temperature
2. Increasing concentration
3. Increasing pressure
4. Increasing surface area
5. Using a catalyst

Question 5

Increasing temperature

Answer 5

As there is more heat energy, this is converted into kinetic energy. As the particles move faster the reactions are more vigorous as the particles hit each other harder

Question 6

Increasing concentration

Answer 6

There are more particles in the same amount of area meaning they are more likely to hit into each other

Question 7

Increasing pressure

Answer 7

This means there is less volume for the reaction meaning that the particles are more likely to hit into each other.

Question 8

Increasing the surface area

Answer 8

As there is more area to hit it is more likely for the particles to hit one another

Question 9

Using a catalyst

Answer 9

A catalyst increases the rate of reaction and is a separate substance that is added