ECHE 311-Spring 2015
Quiz 7
1. For a system in which the following reactions occurs,
A  B  C  3D
assume there are present initially 2 mol A, 1 mol B, 1 mol C and 4 mol D. Determine
expression for the mole fraction
Hint:
yi 
yi as functions of  .
ni nio   i

n no  
(15 points)
1
2. For the above reaction
(a) specify the data that are necessary for calculation of the equilibrium constant.
(b) show the routine for calculation of the equilibrium constant at given temperature.
(15 points)
2
3. For the reaction
CO( g )  H 2O( g )  CO2 ( g )  H 2 ( g )
the reactants consist of 1 mole of H2O vapor and 1 mol of CO. Assume the mixture
behaves as an ideal gas, define
of
K
K y . Also write equation which defines the dependence
on the fraction of steam that reacts
.
( 25 points)
3
4. Equation
d ln K H o

dT
RT 2
gives the effect of temperature on the equilibrium constant. Equilibrium expression
displaying the pressure and the composition for ideal gas phase reactions is given by:
 ( yi )vi = (
i
P 
) K
o
P
The above two equation can be used to predict the shift of the reaction as a function of
temperature for exothermic and endothermic reactions.
(a) Define the conditions when
(b) Define the conditions when
(c) Define the conditions when
 e will decrease
 e will increase
 e will increase with an increase of P at constant T.
(25 points)
4
5. Equilibrium constant at 600oC for the reaction
H 2( g )  I 2( g )  2HI
is 70.5. If initial mixture consists of “a” moles of hydrogen and “b” moles of iodine
determine the equilibrium concentrations (moles of hydrogen, moles of iodine and moles
of HI).
(20 points)
5