A5 Equilibria

Question 1

Using Le Chatalier’s principale explain the effect of increasing temperature

Answer 1

• Forwards reaction is exo/endothermic
• So increasing temperautre favours forwards/backwards reaction
• Equilibrium concentration of XXX increases

Question 2

Define dynamic equilibria

Answer 2

• Exists only in a closed system
• The rate of the forward reaction is equal to the rate of the reverse reaction
• The concentrations of reactants and products do not change

Question 3

Using Le Chatalier’s principale explain the effect of increasing pressure

Answer 3

• Fewer gas moles on the left/right
• Increasing pressure shifts equallibrium to the left/right hand side
• Equilibrium concentration of XXX incresaes

Question 4

Using Le Chatalier’s principale explain the effect of increasing concentration of reactants

Answer 4

• More reactant particles in mixture per unit volume
• Equilibrium shifts to right hand side

Question 5

Using Le Chatalier’s principale explain the effect of a catalyst

Answer 5

• Increases the rate of both the forwards and backwards reactions in the equilibria by the same ammount
• The position of equalibria remains unchanged

Question 6

In equilibria industry, what are the advantageous/disadvantages to temperature

Answer 6

• High temperature = quicker rate
• High temperature is expensive

Question 7

In equilibria industry, what are the advantageous/disadvantages to pressure

Answer 7

• High pressure = quicker rate
• High pressure = expensive
• High pressure = dangerous

Question 8

Why is it difficult to know the effect on equalibria if it is affected by both temperature and pressure

Answer 8

Difficult to predict relative contributions of two opposing factors

Question 9

Why is nitrogen accesible in industry

Answer 9

Occurs naturally in the air

Question 10

Explain the effect of changing temperature on the position of Kc

Answer 10

• If temperature change causes equilibria to shift to the right hand side, Kc value increases
• If temperature change causes equilibria to shift to the left hand side, Kc value decreases
• Kc value is not affected by pressure, or catalysts

Question 10

Stages required for Kc with brief explaination of each one if applicable

Answer 10

• Initial moles
• Change in moles (use molar ratio, and oppostie sides of the equation are positive and negative)
• Equilibrium moles
• Concentration (Conc=mol/vol)

Question 11

What should always be ignored in Kc calculations

Answer 11

Solids

Question 12

Stages for calculating Kp with a brief explaination of each one if applicaible

Answer 12

• Initial moles
• Change in moles (use molar ratio and opposite sides of equation have opposite signs)
• Equilibrium moles
• Mole fraction (E moles over total moles)
• Partial pressure (multiply by volume)

Question 13

What reactants and products should only be used in a Kp calculations

Answer 13

Gases only

Question 14

Explain the effect of increasing pressure (causing right hand shift) on the Kp equation

Answer 14

• Equallibrium shifts right, as right hand side has fewer moles
• Increased pressure results in denominator of Kp experssion increasing more than numerator
• Numerator expression must increase to restore Kp

Question 15

Explain how increasing temperature affects the value of Kp

Answer 15

• If temperature change causes equalibira to shift to right hand side, Kp value increases
• If temperature change causes equalibira to shift to left hand side, Kp value decreases
• Kp value is not affected by pressure, or catalysts