19. Equilibrium

Question 1

Kc expression for:
N2(g) + 3H2(g) <—> 2NH3(g)

Answer 1

Kc = ( [NH3(g)]^2 ) / ( [N2(g)] [H2(g)]^3 )

Question 2

units of Kc:

Answer 2

sub mol dm^-3 into expression
cancel common terms

Question 3

units of Kc:
H2 + I2 = 2HI

Answer 3

( (moldm^-3)^2 ) / ( (moldm^-3)^2 )
= no units

Question 4

units of Kc:
2SO2 + O2 = 2SO3

Answer 4

(x^2) / (x^2) (x)
= 1/x
= dm^3 mol^-1

Question 5

homogenous equilibria

Answer 5

all species have the same state or phase.
N2 (g) + 3H2 (g) <-> 2NH3 (g)

Question 6

heterogenous equilibria

Answer 6

species have different states or phases
C (s) + H2O (g) <-> CO (g) + H2 (g)

Kc = ( [co2] [h2] ) / ( [h2o] )
units = mol dm^-3

Question 7

calculate Kc:
2NO (g) + O2 (g) <-> 2NO2 (g)
1.60 mol NO (g), 1.40 mol O2 (g) mixed together in a container with a volume 4.00 dm^3.
at equilibrium, 1.20 mol NO2 (g) has formed.

Answer 7

= 45 dm^3 mol^-1 (page 32 kerboodle)

Question 8

determine Kc from experimental results part 1
[A] CH3COOH + [B] C2H5OH <-> [C] CH3COOC2H5 + [D] H2O
carboxylic acid + alcohol reaction.

Answer 8

1. in a conical flask, mix 0.100 mol [A] and 0.100 mol [B].
   add 0.050 mol of HCl (aq) as an acid catalyst to the flask.
   total volume= 20.0 cm3
   the amount of water in the aqueous acid catalyst is 0.500 mol.
2. add 0.05 mol HCl into 2nd flask as control
3. stopper both flasks and leave for a week to reach equilibrium.
4. carry out titration on the equilibrium mixture using a standard solution of sodium hydroxide
5. repeat with control to determine the amount of acid catalyst that had been added.