Equilibria Flashcards
State the effect on the equilibrium position and the rate of attainment of equilibrium if the concentration of a catalyst were to be increased
- Equilibrium position would no change
- Rate of attainment of equilibrium would increase
Ethanolic acid and ethanol react together to form the ester ethyl ethanoate and water
Give the expression for Kc
Kc = [CH3COOCH2CH3(l)] [H2O(l)] / [CH3COOH(l)] [CH3CH2OH(l)]
Explain why Kc sometimes has no units
-If units on top and bottom of the equation are equal, units cancel
Identify which bonds are broken and which bonds are made in this reaction:
CH3COOH + CH3CH2OH CH3COOCH2CH3 + H2O
Explain why ΔH is not exactly zero
BONDS BROKEN:
C-O and O-H
BONDS MADE:
C-O and O-H
- Bond enthalpies are different in different molecules
- Bond enthalpies are average values
State the relationship between ΔStotal and the equilibrium constant, K, of a reaction
ΔStotal = R Ink
Equation for preparing ethyl ethanoate using ethanoyl chloride
CH3CH2OH + CH3COCl –> CH3COOCH2CH3 +HCl
Ethanoyl chloride reacts with concentrated ammonia. Give the structural formula of the product
CH3CONH2
AMIDE
Equation for the alkaline hydrolysis of ethyl ethanoate using sodium hydroxide
CH3COOCH2CH3 + NaOH –> CH3COONa + CH3CH2OH
Explain why alkaline hydrolysis gives a better yield of alcohol compared with acid hydrolysis of ethyl ethanoate
-Reaction with NaOH is not reversible/goes to completion
State the effect on the value of Kp of increasing the pressure of the reaction
-No effect on Kp value
Increasing the pressure on a heterogeneously-catalysed reaction has very little effect on the rate of reaction. Suggest why this is so
-Reaction takes place on surface of catalyst
–Catalyst surface saturated with reactant molecules
Write the equation for the thermal decomposition of potassium hydrogencarbonate
2KHCO3 –> K2CO3 + CO2 + H2O
Although industrial processes are often discussed in terms of equilibria, they are rarely allowed to reach equilibrium. Suggest why, apart from insufficient reaction time, this is so
- Balance between time and yield
- More product in unit time which is more economically viable
