Rate of Reaction and Equilibrium Systems

Question 1

Collision Theory

Answer 1

1) Reactants must collide
2) with sufficient energy (greater that activation energy)
3) and correct orientation

Question 2

Maxwell-Boltzmann Distribution

Answer 2

For a reaction to occur, the particles must have energy greater than the activation energy. These particles are shown under the curve, to the right of the activation energy.

Question 3

Rate of Reaction

Answer 3

speed at which a reaction occurs measured by the change in concentration of a reactant or product per unit time.

Question 4

SURFACE AREA

Answer 4

• If a solid reactant is broken into small pieces or ground into a powder:
• Its surface area is increased.
• More particles are exposed to the other reactant and the collision frequency
increases.
• There is a greater frequency of successful collisions between particles. • The
rate of reaction increases.

Question 5

TEMPERATURE

Answer 5

• If the temperature of a reaction is increased:
• The average kinetic energy of particles is increased.
• This results in a greater proportion of particles having energy equal to or
greater than the activation energy
• This results in a higher proportion of collisions being successful, and
therefore a higher frequency of successful collisions.
• The rate of reaction increases

Question 6

CONCENTRATION

Answer 6

• If the concentration of a reactant is increased:
• There is a higher number of reactant particles per unit volume.
• This results in an increase in collision frequency.
• There is a greater frequency of successful collisions between particles.
• The rate of reaction increases.

Question 7

Activation energy

Answer 7

minimum amount of energy required for a reaction to take place

Question 8

catalyst

Answer 8

substance that speeds up the rate of reaction by lowering activation energy, remaining unchanged by the reactions

Question 9

Dynamic Equilibrium

Answer 9

• rate of the forward reaction equals the rate of the reverse reaction, resulting in no observable change overtime
• forward reaction : more products than reactants
• reverse reaction : more reactants than products

Question 10

Le Chatelier’s Principle

Answer 10

• a system at equilibrium has a tendency to partially oppose every change that you make to it, assuming the change disrupts equilibrium somehow.
• If the forward reaction is favoured we say the equilibrium has moved to the right
• If the reverse reaction is favoured we say the equilibrium has moved to the left

Question 11

Endothermic

Answer 11

• +ve
• absorbs heat from its surroundings
• more products that reactants

Question 12

Exothermic

Answer 12

• -ve
• releases heat to its surroundings
• more reactants than products

Question 13

Effect of Changing Temperature on Equilibrium

Answer 13

Increasing temperature will always favour the endothermic forward reaction shifting equilibrium to the right.

Decreasing temperature will always favour the exothermic reverse reaction shifting equilibrium to the left.

Question 14

Effect of Changing Concentration on Equilibrium

Answer 14

more reactants : forward
less reactants : reverse
more products : reverse
less products : forwards