1.At 20°C the vapour pressure of benzene (C6H6) is 76.0 mm Hg, and that of toluene (C7H8) is 21.8 mm Hg. Hence both components are volatile. What is the mole fraction of each component in an ideal solution of benzene and toluene that has a vapour pressure of 35.4 mm Hg at 20°C? b) List the following solutions in order of decreasing freezing point: 0.04 molal glycerol (C3H8O3); 0.025 molal KBr; 0.030 molal phenol (C6H5OH). 2.At 250°C, an equilibrium mixture contains 0,096 mol.dm–3 CO, 0,191 mol.dm–3 H2, and 0,015 mol.dm–3 CH3OH. (a) What is the value of Kc at 250°C for the following reaction? CO (g) + 2 H2 (g) ⇌ CH3OH (g) (b) What is the value of Kc for the following reaction? 2 CO (g) + 4 H2 (g) ⇌ 2 CH3OH (g) 3.A mixture of SO3, SO2 and O2 at 727°C is at equilibrium according to the equation: SO2 (g) + ½ O2 (g) ⇌ SO3 (g) (a) The mixture is 0,0160 mol.dm–3 SO3, 0,0056 mol.dm–3 SO2 and 0,0021 mol.dm–3 O2. What is the value of Kc? (b) If Kp is given by: Kp = Kc·(RT)Δn, what is the value of Kp at 727°C? 4.Dinitrogen tetroxide, N2O4, dissociates at room temperature to give nitrogen dioxide, NO2. N2O4 (g) ⇌ 2 NO2 (g) (a) The equilibrium constant Kc at 25°C is 0,125. What percentage of dinitrogen tetroxide is dissociated when 0,0300 mol N2O4 is placed in a 1,00 dm3 flask and left to reach equilibrium? (b) The amount of nitrogen dioxide formed increases as the temperature rises. Is the dissociation of N2O4 endothermic or exothermic? 5. Dinitrogen trioxide decomposes to NO and NO2 in an endothermic process (∆H = + 40,5 kJ/mol). N2O3 (g) ⇄ NO (g) + NO2 (g) Predict the effect of the following changes on the position of the equilibrium; that is, state which way the equilibrium will shift (left, right, or no change) when each of the following changes is made. Motivate each prediction fully. (a) Adding more N2O3 (g) (b) Adding more NO2 (g) (c) Decreasing the temperature (d) Increasing the container volume
1.At 20°C the vapour pressure of benzene (C6H6) is 76.0 mm Hg, and that of toluene
(C7H8) is 21.8 mm Hg. Hence both components are volatile. What is the mole fraction
of each component in an ideal solution of benzene and toluene that has a vapour
pressure of 35.4 mm Hg at 20°C?
b) List the following solutions in order of decreasing freezing point: 0.04 molal glycerol
(C3H8O3); 0.025 molal KBr; 0.030 molal phenol (C6H5OH).
2.At 250°C, an equilibrium mixture contains 0,096 mol.dm–3 CO, 0,191 mol.dm–3 H2, and
0,015 mol.dm–3 CH3OH.
(a) What is the value of Kc at 250°C for the following reaction?
CO (g) + 2 H2 (g) ⇌ CH3OH (g)
(b) What is the value of Kc for the following reaction?
2 CO (g) + 4 H2 (g) ⇌ 2 CH3OH (g)
3.A mixture of SO3, SO2 and O2 at 727°C is at equilibrium according to the equation:
SO2 (g) + ½ O2 (g) ⇌ SO3 (g)
(a) The mixture is 0,0160 mol.dm–3 SO3, 0,0056 mol.dm–3 SO2 and 0,0021 mol.dm–3 O2.
What is the value of Kc?
(b) If Kp is given by: Kp = Kc·(RT)Δn, what is the value of Kp at 727°C?
4.Dinitrogen tetroxide, N2O4, dissociates at room temperature to give nitrogen dioxide, NO2.
N2O4 (g) ⇌ 2 NO2 (g)
(a) The equilibrium constant Kc at 25°C is 0,125. What percentage of dinitrogen tetroxide
is dissociated when 0,0300 mol N2O4 is placed in a 1,00 dm3 flask and left to reach
equilibrium?
(b) The amount of nitrogen dioxide formed increases as the temperature rises. Is the
dissociation of N2O4 endothermic or exothermic?
5. Dinitrogen trioxide decomposes to NO and NO2 in an endothermic process (∆H = + 40,5
kJ/mol).
N2O3 (g) ⇄ NO (g) + NO2 (g)
Predict the effect of the following changes on the position of the equilibrium; that is, state
which way the equilibrium will shift (left, right, or no change) when each of the following
changes is made. Motivate each prediction fully.
(a) Adding more N2O3 (g)
(b) Adding more NO2 (g)
(c) Decreasing the temperature
(d) Increasing the container volume
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