Topic 1 - 1.1 - Chemical Reactions

Question 1

What is a chemical reaction?

Answer 1

When one or more substances react together to produce one or more new chemical substances.

Question 2

Define the rate of reaction

Answer 2

It is a measure of how fast the reactants are being used up and how fast the products are made.

Question 3

What are reactants and products?

Answer 3

Reactant - Substances changed by the chemical reaction
Products - Substances produced by the chemical reaction

Question 4

Name and describe 4 signs of a chemical reaction

Answer 4

• Colour change - can happen during thermal decomposition
• Effervescence - when reaction occurs inside a liquid and produces bubbles of gas
• Precipitation - when soluble liquids react together to form an insoluble solid
• Energy Change - in the name (IT IS POSSIBLE TO GET NEGATIVE ENERGY CHANGES - IT MEANS THE REACTION IS ENDOTHERMIC

Question 5

What is an exothermic reaction?

energy change

Answer 5

Heat energy is RELEASED as reactant energy > product energy
* increases temperature of surroundings (because energy is release to surroundings)

Question 6

What is an endothermic reaction?

energy change

Answer 6

Heat energy is ABSORBED as reactant energy < product energy
* decreases temperature of surroundings (because reaction absorbs energy)