Download Equilibrium calculations 2

Equilibrium calculations 2
Calculating the equilibrium constant, Kc, given the balanced equation, the
initial concentrations (or amounts) and the equilibrium concentration (or
amount) of at least one substance
1. 6.75 g of SO2Cl2 was put into a 2.00 dm3 vessel, the vessel was sealed and
its temperature raised to 375 oC. At equilibrium the vessel contained
0.0345 mol of Cl2. Calculate the equilibrium constant for the reaction
SO2Cl2 (g)
SO2 (g) + Cl2 (g)
a. Note that the number of molecules does change, so we have to calculate
concentrations from amounts.
b. Write the balanced equation, leaving room for initial concentrations and
equilibrium concentrations below each species.
c. Calculate the initial concentrations and put the values above the
appropriate formulae in the equation. You need to use n = m / Mr and then c
= n / V.
d. Now work out the equilibrium concentrations from the data and the
equation.
Write these equilibrium concentrations under your equation.
e. Write the equilibrium law expression and put in the numbers you’ve just
worked out. Don’t forget the units for Kc.
2. Ethanoic acid, CH3COOH, and pent-1-ene, C5H10, react to produce pentyl
ethanoate (an ester) in an inert solvent. A solution was prepared containing
0.020 mol of pent-1-ene and 0.010 mol of ethanoic acid in 600 cm3 of
solution. At equilibrium there was 9.0 x 10-3 mol of pentyl ethanoate.
Calculate the value of Kc from these data.
CH3COOH + C5H10
CH3COOC5H11
What do you think the structure of the product is?
3. A mixture of 1.90 mol of hydrogen and 1.90 mol of iodine was allowed to
reach equilibrium at 710 K. The equilibrium mixture was found to contain 3.00
mol of hydrogen iodide. Calculate the equilibrium constant, Kc, at 710 K for
the reaction.
H2 (g) + I2 (g)
2 HI (g)
4. If a mixture of 6.0 g of ethanoic acid and 6.9 g of ethanol is allowed to
reach equilibrium, 7.0 g of ethyl ethanoate is formed. Calculate Kc.
CH3CO2H + C2H5OH
CH3CO2C2H5 + H2O