Kinetics

Question 1

Rate of Reaction

Answer 1

The decrease in the concentration of reactants per unit time, or the increase in the concentration of products per unit time

Question 2

Ea

Answer 2

The minimum energy the colliding particles need in order to react

Question 3

Reactions can be made faster in two ways:

Answer 3

1. Increasing collision frequency

2. Increasing fraction of successful collisions

Question 4

The rate of a chemical reaction can be changed in a number of ways:

Answer 4

1. by changing the concentration of the reacting particles
2. by changing the pressure of the system (if some of the reacting particles are in the gas phase)
3. by changing the particle size (if some of the reacting particles are in the solid state)
4. by changing the temperature of the system
5. by adding a catalyst

Question 5

An increase in concentration + pressure increases the rate of reaction because

Answer 5

the number of particles per unit volume increases so the collision frequency increases

Question 6

A decrease in particle size increases the rate of reaction because

Answer 6

the surface area increases so the collision frequency increases

Question 7

An increase in temperature increases the rate of reaction because

Answer 7

The mean collision energy of the particles increases so more of the particles have a collision energy greater than the activation energy so the fraction of successful collisions increases and the particles are moving faster so the collision frequency increases

Question 8

A catalyst is a

Answer 8

Substance which changes the rate of a chemical reaction without itself being chemically altered at the end of the reaction.

Question 9

A catalyst increases the rate of reaction because

Answer 9

The activation energy of the particles decreases so more of the particles have a collision energy greater than the activation energy so the fraction of successful collisions increases