5.1.2 How Far?

Question 1

What is Kc

Answer 1

Equilibrium constant

Question 2

Kc equation

Answer 2

mA + nB -> pC + qD

Kc = ([C]^p x [D]^q) all divided by ([A]^m x [B]^n)
Products/ reactants

Question 3

How do you work out units for Kc?

Answer 3

Place units for each reactant/product into the equation and cancel out

Question 4

Calculating moles at equilibrium

Answer 4

Moles of reactant= initial - moles reacted

Moles of products = initial moles + moles formed

Question 5

Calculating Kc

Answer 5

Use MICE
moles
Initial 
change
Equilibrium

Question 6

Practical to work out equilibrium constant Kc

Answer 6

Ethanoic acid and ethanol reacted with sulfuric acid catalyst to make ethyl ethanoate

Question 7

Stages to work out Kc in the practical

Answer 7

Work out initial amount of moles using mass density volume and then moles mass mr
Work out equilibrium moles of acid present from titre
Work out all equilibrium moles
Calculate Kc

Question 8

Partial pressure definition

Answer 8

Pressure a gas would have alone if it occupied the volume occupied by the whole mixture

Question 9

how do tou calculate partial pressure of a gas

Answer 9

Mole fraction x total pressure of gas

Question 10

Mole fraction equation

Answer 10

number of moles of a gas divided by total number of moles of all gases

Question 11

All partial pressures added together should equal what

Answer 11

Total pressure of gases

Question 12

Kp

Answer 12

Equilibrium constant for gases
Using partial pressures
Products/ reactants

Question 13

Kp expressions only contain what

Answer 13

Gaseous substances

Heterogeneous equilibria

Question 14

What do Kc anx Kp change with

Answer 14

Temperature

Question 15

Effect of temperature on Kc and Kp

Answer 15

Position of equilibria will change
Temp increased reaction favours endothermic
Shifts left
Kc decreases

Question 16

Effect of concentration on Kc and Kp

Answer 16

Shift equilibrium but values dont change
Increases concentration moves equilibrium to right and increases other concentration
Restores equilibrium

Question 17

Effect of catalysts on Kc and Kp

Answer 17

No effect

Speeds forwards and backwards reactions at same rate

Question 18

Effect of pressure on Kc

Answer 18

Increased pressure reaction will shift to side with fewer moles of gas
Shifts right
Kc stays same
Increases conc on bottom of equation so top increases and bottom decreases to restore values

Question 19

Effect of pressure on Kp

Answer 19

Kp stays constant
Increases pressure on bottom of equation so shifts right to increase mole fraction of products to decrease mole fraction of reactants
Kp is restored