TOpic 6 Energy changes in chemical reactions

Question 1

What is an exothermic reaction (2)

Answer 1

A reaction that releases thermal energy to the surrounding

Increases the temperature of the surroundings

Question 2

What is an endothermic reaction (2)

Answer 2

A reaction that takes in thermal energy from the surroundings

decreases the temperature of the surroundings

Question 3

Define system

Answer 3

consists of particles that are involved in a chemical reaction

Question 4

Define surroundings

Answer 4

The matter surrounding the site of a chemical reaction that energy is either transferred into or out of

Question 5

Explain exothermic reaction in relation to bond energies(2)

Answer 5

The energy released when creating a new bond (exothermic)is greater than the energy needed to break the reactant bonds. (endothermic)

The surplus energy is released to the surroundings int he form of heat

Question 6

Explain endothermic reaction in relation to bond energies (2)

Answer 6

The energy needed to break the reactant bonds (endothermic) is greater than the energy released when creating new bonds (exothermic)

There is a shortage of energy and so energy is taken in from the surroundings

Question 7

Define enthalpy (2)

Answer 7

measure of the potential energy a chemical has

given the symbol H

Question 8

Define activation energy

Answer 8

minimum amount of energy required for a reaction to occur

Question 9

What process is breaking bonds

Answer 9

endothermic process

Question 10

Making/releasing bonds is what process

Answer 10

exothermic process