Chemical Reactions

What is a physical change?

Matter changes shape/state but no new substance is formed

Can you reverse physical changes?

Yes

What is a chemical change?

A chemical reaction occurs & a new substance is formed

Can you reverse a chemical change?

It is difficult to reverse

What do chemical changes involve?

Heat change

What is a chemical reaction?

2/more substances combine yo form a new substance

What occurs during a chemical reaction?

Energy changes

What is the law of conservation of Mass?

Matter can’t be created/destroyed in a chemical reaction. It’s only rearranged. The no. Of atoms on both sides of the reaction remain the same

what does exothermic mean?

Releases heat

What does endothermic mean?

Absorbs heat

What is the rate of reaction tell us?

How quickly/slowly a chemical reaction is taking place

What are factors that affect the rate of a chemical reaction?

Surface area & size of particles, catalysts, temperature, concentration of reactants

What will happen to a chemical reaction if heated?

They gain energy and more collisions occur

What happens if you increase the surface area in a chemical reaction?

Faster reaction time due to more collisions

How does the concentration of reactants affect a chemical reaction?

A concentrated solution will have more reactant particles and will react faster. A dilute solution has less reactant particles so it has a slower reaction time

What do catalysts do?

It speeds up a chemical reaction without being used up. It lowers the activation energy needed for a reaction to occur

What is an activation energy?

Minimum amount of energy needed for a reaction to take place

What does an energy profile diagram represent?

Energy changes that occur during a reaction