Equilibrium

What are the three conditions required for equilibrium?

1. Constant macroscopic properties

2. Forward rate equals to reverse rate

3. Closed system

What is not required for a system to be in equilibrium?

The concentration of reactants and products being same

what does equilibrium look like on a [ ] vs time graph?

The [ ] stay constant

what does equilibrium look like on a RATE vs time graph?

The forward and reverse reaction rate converge (equal to each other)

Chemical reactions favour the side with … enthalpy, so … reactions are favoured because …

Minimum; exothermic; more stable

Define entropy

The amount of randomness in a system

Systems tend towards … entropy

Maximum

from solid to gas, entropy …

Increases

As number of particles decreases, entropy …

Decreases

solely looking at enthalpy and entropy, if the forward reaction is favoured by one, and the reverse reaction by the other. The reaction will …

Reach equilibrium

when a stress is placed on an equilibrium, it will … to counteract the stress, and a … will be reached

Shift, new equilibrium

Define a shift

The rate that is initially faster

The E is will shift towards the side with … concentration

Lower

Changes in concentration only applies to …, and not … because they have …

Solutions and gases; pure solids and liquids; constant concentrations

increasing [reactant] shifts …, [product] …, and [reactant] …

To the right/ product/ forward rxn ; increase; decrease

An increase pressure will shift the equilibrium in the direction of … molecules

Fewer

A change in pressure only affects equilibrium when there is an … # of mols of … on either side of the equilibrium

Unequal; gas

Why does an increase in pressure favor the side with fewer particles? (AP)

For example 2H2 + H2O $\lrArr$ 2H2O

Overall, there are more collisions, but the % of effective collisions of the forward direction increased more relative to the increase of the % of effective collisions of the reverse reaction, so the forward reaction is initially higher.

Using the same logic explain why a increase in volume / decrease in pressure favor the side with more particles (AP)

The decrease in the percentage of effective collisions of the reaction with more particles will be greater than the same decrease in the reaction with less particles.

In addition, if the change in pressure is due to a non-reactive gas there will be … shift in the equilibrium. Because the … pressure of substances has stayed same. (AP)

No; partial

for example 2H2 + O2 $\lrArr$ 2H2O, reduce volume, what is the shift and result?

Shift right, increase in products, and reactants decrease

An increase in temperature will favor the rate of the …

Endothermic reaction

Why does an increase / decrease in temperature favour the endothermic / exothermic reaction? Chem 12

Reaction will want to remove excess / increase the heat

Why does an increase in temperature favour endothermic reaction? AP

Endothermic reaction has a greater increase in the % of effective collisions so the rate is faster initially.

Using the same logic why does a decrease in temperature favor the exothermic reaction?

The % decrease of effective collisions of the endothermic reaction will be greater than the same decrease of the exothermic reaction, initially the exothermic reaction will be faster / favored.

Catalyst will have … equilibrium, only how … the system gets to equilibrium

No affect on; fast