10: Kinetics And Equilibrium

Question 1

Kinetics def

Answer 1

Is the study of the rate at which reactant molecules are converted to products in a chemical rx.

Question 2

Equilibrium

Answer 2

The point in a chemical rx at which conc of reactants and products doesn’t change.

Question 3

Conditions for bond breaking and bond making to occur

Answer 3

Reactant molecules must collide with sufficient energy, to break bonds, and proper orientation, to form new bonds.

Question 4

What is activated complex or transition state

Answer 4

It’s a high energy arrangements of atoms that reactants form before products can be made

Question 5

Catalyst facts

Answer 5

• increase the rate of the reaction by lowering the activation energy.
• doesn’t change the equilibrium of a rx
• not consumed in the rx.

Question 6

Factors the affect reaction rate

Answer 6

• conc. Of reactants (for gases, by increasing pressure which increases conc, or solutions, not pure solids or liquids that can’t be compressed)
• surface area of reactants ( for only solids, grinding, and liquids, spraying)
• temperature ( foremost, due to increase of rate of reactant’s collision and energy involved)
• Nature of reactants ( strong or weak bonds, rx btn dissolved ions is rapid due to absence of bonds.
• catalyst (lowers activation energy needed to form the activated complex)

Question 7

Factors affecting frequency of collision, and factors affecting energy of collision, which affect reaction rate

Answer 7

Factors affecting frequency of collision
- temperature
- conc. of reactants
- surface area of reactants
Factors affecting energy of collision
 - temperature
- nature of reactants
- catalyst

Question 8

What does equilibrium NOT mean

Answer 8

It doesn’t mean that the concentrations of reactants and products are equal. It simply means that whatever the conc. of products or reactants doesn’t change, is constant, at equilibrium.

Question 9

Which species that do not belong in the equilibrium expression

Answer 9

Solids and pure liquids bcs their conc. Doesn’t vary.

Question 10

Effects of Keq on the direction of rx

Answer 10

• Keq > 1, forward rx favoured (conc. of products greater than that of reactants)
• Keq < 1, reverse rx favoured (conc. of products less than that of reactants)

Question 11

Let chatelier’s principle

Answer 11

If some stress is placed on a reaction at equilibrium, then the equilibrium will shift in the direction that relieves the stress

Question 12

Which equilibrium of a rx would NOT be affected by change in pressure or volume

Answer 12

The equi of a rx that involves equal moles of gaseous reactants and products.

Question 13

Effects of catalyst on equilibrium

Answer 13

It doesn’t; it only affects the rx rate.

Question 14

What is solubility product constant (Ksp)

Answer 14

It is the equilibrium btn a so called insoluble ionic solid and it’s dissolved ions

• even the most insoluble ionic precipitate dissolves into ions in water to a certain degree.
• since the forward reaction is so insignificant, the Ksp values are very small. The smaller the Ksp the more insoluble is the ionic solid.