C6 & C7

Question 1

What is the collision theory?

Answer 1

Activation energy: Chemical reactions can only happen if
reactant particles collide with enough
energy. This initial energy is called the activation energy

Question 2

What are the two equations for rate?

Answer 2

Amount of reactant used up ÷ Time

Amount of product formed ÷ Time

Question 3

What happens to reactions when temperature is increased?

Answer 3

Particles convert the thermal energy into kinetic energy. The more they move the more frequent collisions - the more effective collisions. The faster the RATE OF REACTION

Question 4

What is a catalyst?

Answer 4

A substance that can increase the rate of reaction without being used up itself

Question 5

What happens to reaction when pressure/ concentration is increased?

Answer 5

With higher pressure concentration/ pressure come more particles which cause more collisions - more frequent collisions - more effective collisions. Faster RATE OF REACTION

Question 6

What happens to a reaction when the surface area is increased?

Answer 6

The larger the surface area the more particles are exposed to other reactants. There are more collisions - More effective collisions.

Question 7

What is Oxidation? What is reduction?

Answer 7

Oxidation is the addition of energy to a substance. It loses electrons.
Reduction is the removal of oxygen from a substance.
*Reduction and oxidation always take place together

Question 8

What is being oxidized and what is being reduced?

1. 2Ca + O2 —> 2CaO
2. NaBr + Cl2 —> NaCl + Br2

Answer 8

1. Ca = Oxidized, O = Reduced

2. Br = Oxidized, Cl = Reduced

Question 9

what are the rules for the arrangement of electrons

Answer 9

Up to 2 electrons can exist in the first shell
Up to 8 electrons can exist in the second and third shell

Top number - Mass number: number of protons + neutrons
Bottom number - Atomic number: number of protons = number of electrons

Question 10

What is an exothermic reaction?

Answer 10

An exothermic reaction is a reaction in which heat is given out so the temperature outside goes down. Bonds in the REACTANTS have more energy than the products.
*ΔH=negative

Question 11

What is an endothermic reaction?

Answer 11

An endothermic reaction is a reaction in which heat enters so the temperature outside decreases. The bonds in the REACTANTS have less energy than the PRODUCTS
*ΔH=positive