How far?

Question 1

What is kp?

Answer 1

the equilibrium constant for a gas phase reaction

Question 2

What does a large kc value mean?

Answer 2

means the position of equilibrium lies to the right

Question 3

what does a very small kc value mean?

Answer 3

position of equilibrium lies to the left.

Question 4

what would a kc value of one suggest?

Answer 4

that the reaction lies half way between the reactants and the products

Question 5

What happens to the number of molecules during reversible reaction? (equilibrium moles)

Answer 5

the total number of moles of substance is not conserved or constant (although the total number of atoms are conserved) e.g. the dehydrogenation of ethane to produce ethene and hydrogen

Question 6

in a reversible reaction to her dies cincersin of the reactants into products result in?

Answer 6

the number of moles of products increasing and the number of moles of reactants decreasing. (opposite can also occur, if there is a mixture of reactants and products, or just products.
Given the change in one of the components of the mixture we can deduce all the others.)

Question 7

when do we not need to work out the equilibrium concentrations?

Answer 7

if there are an equal number of moles on both sides (volumes cancel in Kc(because c=n/vx1000))

Question 8

What is kc only affected by?

Answer 8

change in temp

Question 9

If you have a mixture of gases (A, B, C, etc), how is the moles fraction of gas a worked out?

Answer 9

by dividing the number of moles of A by the total number of moles of gas

Question 10

What symbol is the mole fraction of gas A and gas Bgiven?

Answer 10

XA
XB etc

Question 11

What is the equation of type mole fraction of gas A?

Answer 11

XA = number of moles of gas A/total number of moles of gas

Question 12

What is the partial pressure of one of the gases in a mixture,

Answer 12

the pressure which it would exert if it alone occupied the whole container

Question 13

What symbol partial pressure of gas A often given?

Answer 13

PA

Question 14

what is the total pressure of gases due to? (first relationship)

Answer 14

both molecules hitting the walls - in other words, the sum of the partial pressures.

Question 15

what is the equation to work out PA?

Answer 15

PA- mole fraction of A (XA) x total pressure

Question 16

What is partial pressure measured in?

Answer 16

ATM

Question 17

What is homogenous equilibrium?

Answer 17

which everything in the equilibrium mixture is present in the same phase. In this case, to use Kp, everything must be a gas

Question 18

when can the partial pressures of the everything be worked out?

Answer 18

if you allow the reaction to reach equilibrium

Question 19

What do kc and kp always have provided you don’t change the temperature?

Answer 19

same temp

Question 20

what is the format of kp?

Answer 20

same as kc except partial pressure is used instead of conc

Question 21

What is the effect of temp on kc/kp?

Answer 21

inc temp shifts the equilibrium in the direction of the endothermic reaction
to absorb the heat energy (lowers or increases the reactant concentration)
Dec temp shifts the equilibrium in the direction of the exothermic reaction to release the heat energy and (lowers or increases the reactant concentration)

Question 22

what happens be lays the reactants are on the bottom of the kc or kp expression (concentration)

Answer 22

reactant concentration increases, Kc/Kp decreases in magnitude.
If reactant concentration decreases, Kc/Kp increases in magnitude.

Question 23

What happens if you change the concentration or pressure of an equilibrium mixture? (one mark)

Answer 23

Kc/Kp does not change

Question 24

State and explain the hat happens in a system when the conc or pressure of an equilibrium mixture changes-

Answer 24

1. write kp expression
2. when pressure is increased, pp of all gases will increase (denom/num will increase if there are more moles on one side
   3.Le chateliers principe
   4 what happens to kp after the shift -Denominator decreases and Kp is restored to its original value.
   (numerator also increases but you don’t need to explain both changes)

Question 25

is the dissociation of chlorine exothermic or endothermic?

Answer 25

This reaction is endothermic; when T is increased the equilibrium shifts to
the RHS, this shift absorbs energyby making the forward reaction increase its rate.

Question 26

why does the dissociation of chlorine happen more readily in the stratosphere than the atmosphere?

Answer 26

pressure decreases as you go higher in the atmosphere. At lower pressure the equilibrium will shift to the RHS; this means dissociation is greater.