S_04

Question 1

A reversible chemical reaction has reached equilibrium at macroscopic level when:

Answer 1

the concentrations of the reactants and products dont change anymore

Question 2

A reversible chemical reaction has reached equilibrium at molecular level when:

Answer 2

The rate of the formula rxn is equal to the rate of the reverse reaction

Question 3

Reaction that never stops is in —

Answer 3

dynamic equilibrium

Question 4

Equation for equilibrium

Answer 4

K = ( [C]^c [D]^d ) / ([A]^a [B]^b)

Question 5

Equation for reaction quotient (Q)

Answer 5

Q = ( [C]^c [D]^d ) / ([A]^a [B]^b)

Question 6

Calculate the equilibrium constant at a given T for the reaction 2 SO3(g) —-> 2 SO2(g)
+ O2(g), if at equilibrium [SO2] = 0.44 M; [O2] = 0.22 M; [SO3] = 0.11 M.

Answer 6

3.5 p.3

Question 7

If K > 1

Answer 7

Products predominate -> forward reaction is favoured

Question 8

If K < 1

Answer 8

Reactants predominate -> reverse reaction is favoured

Question 9

If K = 1

Answer 9

Neither products or reactants are favoured

Question 10

Equation for reversed reaction

Answer 10

Kforward = k^-1 reverse

Question 11

When equations are added what happens to K

Answer 11

K is multiplied

Question 12

In heterogeneous equilibria the concentration only depends on ?

Answer 12

density of pure solid or liquid

Question 13

n heterogeneous equilibria the quantity of a solid or pure liquid affects K how?

Answer 13

Does not influence K

Question 14

The partial pressure of a gas is proportional to its

Answer 14

Concentration

Question 15

Relationship between Kp and Kc Equation

Answer 15

Kp = Kc (RT) ^(∆n)
R = 0.08206 L x atm/mol x K

Question 16

∆n = ?

Answer 16

moles of gaseous products - moles of reactants

Question 17

For equilibrium reactions, Keq increases with?

Answer 17

Increasing temperature

Question 18

For equilibrium reactions, Keq decreases with?

Answer 18

Decreasing temperature

Question 19

The reaction quotient (Q) predicts what

Answer 19

the direction of a chemical change

Question 20

If Q=Keq

Answer 20

Reaction has reached equilibrium

Question 21

If Q < Keq

Answer 21

Reaction proceeds to form more products

Question 22

If Q > Keq

Answer 22

Reaction proceeds to form more reactants

Question 23

Chateliers principle

Answer 23

any chnage to a chemical reaction at equilibrium causes the reaction to proceed in the direction that reduces the effect of the change

Question 24

Types of change (3)

Answer 24

[reactant] or [product]
Pressure (by changing volume of reactor)
Temperature

Question 25

Formation of precipitate Q > Ksp =?

Answer 25

The system will react to form solid

Question 26

Formation of precipitate Q < Ksp =?

Answer 26

Equilibrium cannot be established

Question 27

Free energy under nonstandard conditions ∆Grxn =?

Answer 27

∆Grxn = ∆G^* rxn + RTlnQ R = 8.314 J/mol x K

Question 28

If only reactants are present Q=0 ->?

Answer 28

lnQ = ln0 = -inf ∆ Grxn large and negative Reaction will proceed in forward direction

Question 29

If only reactants are present Q=inf ->?

Answer 29

lnQ = ln(inf) = +inf ∆ Grxn large and positive Reaction will proceed in reverse direction

Question 30

If ∆Grxn < 0

Answer 30

Reaction is spontaneous in forward direction

Question 31

If ∆Grxn > 0

Answer 31

Reaction is spontaneous in reverse direction

Question 32

If ∆Grxn = 0

Answer 32

Reaction is at equilibrium Q=K Keq = e^(-∆g^*/RT)

Question 33

Equilibrium cnst K and temperature

Answer 33

∆G = ∆G*+RTlnK = 0 LnK = -∆G* / RT -> lnK = (-∆H*/R) (1/T) + (∆s*/R)