Chemical equilibria

Question 1

what effect does increasing the pressure have on equilibira

Answer 1

Increasing the Pressure -
- the equillibria shifts to the side with fewer molecules. if products have lower moles then yeild increases. the equilibria shifts to oppose this change and decrease the pressure

Question 2

what effect does decreasing the pressure have on equilibira

Answer 2

Decreasing the Pressure -
- the equilibira shifts to the side with more molecules, the equilibira shifts to oopose the change and increase the pressure.

Question 3

what effect does increasing temeperature have on equilibira
- for eg - if the forwards reaction was exothermic

Answer 3

in the example, increasing the temp, favours the endothermic reaction, the equilibrium shift towards the backwards reaction to oppose this so shift in the endothermic reactions direction to decrease the temp.
- decreasing the yeild of product

Question 4

What effect does decreasing the temperature have on equilibira
- for eg - if the forwards reaction was exothermic

Answer 4

decreasing the temperature favours the exothermic reaction, the equilibrium shifts to the forwards reaaction to oppose this so and shifts towards the exothermic reaction and increases the temp.
- increasing the yeild of product.

Question 5

evaluate the benefits and drawbacks of using low temperatures industrially.

Answer 5

Low temperatures may give a higher yield of product but will also result in slow rates of reaction. Often a compromise temperature is used that gives a reasonable yield and rate.

Question 6

evaluate the benefits and drawbacks of using high pressures industrially.

Answer 6

Increasing pressure may give a higher yield of product and will produce a faster rate. Industrially high
pressures are expensive to produce ( high electrical energy costs for pumping the gases to make a
high pressure) and the equipment is expensive (to contain the high pressures)

Question 7

what effect does increasing the concentration of one of the reactants have on the equilibria

Answer 7

increasing the conc of the reactants shifts the equilibira in the forwards direction to oppose this and increasing the yeild of products. and ice versa if the conc of the products increase.

Question 8

what effect do catalysts have on equilibria

Answer 8

they have no effect, they only increaase the rate at which equilibria is reached but not it’s position. this is because it speeds up the rate at which the forwards and the backwards reactions by the same amount.

Question 9

equaion for the hydration of ethene to produce ethanol

Answer 9

CH2 =CH2 (g) + H2O (g) ⇌ CH3CH2OH(l)
Delta H = -ve

Question 10

what factor changes the value of Kc
Only 1

Answer 10

Temperature only.