AS/A-Level Chemistry - Calculations with Kc

Kc From Equilibrium Constants 

N₂O₄⇌ NO₂ 

N₂O₄ and NO₂ are at equilibrium. The amounts present at equilibrium are 3.60g N₂O₄ and 14.70g NO₂. The volume of the container is 200cm³. 

Kc From Initial Amounts 

1 mol ethanoic acid was added to 0.5 moles of ethanol and was left to reach equilibrium. At equilibrium 0.58 mol of ethanoic acid was left.   

CH₃COOH+ CH₃CH₂OH ⇌ CH₃COOCH₂CH₃+ H₂O 

In this instance, the “V”s cancel out and Kc can be derived from moles. 

The Composition of a Reaction Mixture 

1 mole of ethanoic acid was added to one mole of ethanol. If Kc = 4,  calculate the number of moles of ethyl ethanoate and equilibrium. 

CH₃COOH+ CH₃CH₂OH ⇌ CH₃COOCH₂CH₃+ H₂O 

Calculating the Amount of a Reactant Needed 

CH₃COCH₃+ HCN ⇌ CH₃C(CN)(OH)CH₃ 

If Kc = 30 dm³mol^-1 calculate the number of moles of HCN required to produce one mole of produce if you start with 4 moles of propane in 2 dm³ of ethanol (acting as asolvent). 

X = 1.022 mol of HCN 

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