Unit 1: Section 5- Kinetics + RP3 Flashcards
What is dynamic equilibrium?
The rates of the forwards and backwards reaction are the same, the concentrations of the products and reactants are constant.
What is Le Châtelier’s Principle?
Equilibria will change their position to counteract any change in their conditions.
How does increasing pressure effect equilibrium?
If the pressure of a system is increased, the equilibrium opposes the change by shifting to the side which produces the fewest moles of gas to reduce the pressure.
How does decreasing pressure effect equilibrium?
If the pressure of a system is decreased, the equilibrium opposes the change by shifting to the side which produces the most moles of gas to increase the pressure.
How does increasing temperature effect equilibrium?
If the temperature of a system is increased, the equilibrium shifts in the endothermic direction to oppose the change and reduce the temperature by absorbing heat.
How does decreasing temperature effect equilibrium?
If the temperature of a system is decreased, the equilibrium shifts in the exothermic direction to oppose the change and increase the temperature by giving out heat.
How does increasing the concentration of something effect equilibrium?
The equilibrium system will shift in the direction that reduces the concentration of that species.
What happens if you change the pressure of a reaction where there are the same number of moles of gas on each side?
Changes in pressure will have no effect on the position of the equilibrium.
What effect do catalysts have on the position of equilibrium?
Catalysts do not affect the position of equilibrium as they speed up the rate of the reaction of both the forward and backward reaction by the same amount. Catalysts will however cause the system to reach equilibrium more quickly.
What is used in industry to maximise yield of chemical reactions?
Le Châtelier’s principle is used in industry to maximise yield
What is the contact process?
Stage 1: S(s) +O2(g)→SO2(g)
Stage 2: SO2(g) + 1/2 O2(g) ⇌SO3(g)
ΔH=−97 kJ mol −1 (dont need to know numbers)
What temperature is need for the contact process and why?
Stage 2 of the contact process is exothermic so a low temperature is needed to increase the yield. However, a low temperature would cause a slow rate so a compromise is made of 450°C
What pressure is needed for the contact process? (no numbers)
Having a high pressure would lead to high energy costs for marginal gains. This is because the effect of high pressure on yield is only slightly better.
What is the Haber process?
N2(g) +3H2(g) ⇌2NH3(g)
ΔH=−92kJ mol−1
What catalyst is used in the Haber process?
Iron