Page 162 - Modelling in Transport Phenomena A Conceptual Approach

142 CHAPTER 5. RATE OF GENERATION

Solution
Using Eq. (5.3-lo), the number of moles of each species is expressed as

nl = 3 - 2~ = 3 - (2)(1.1) = 0.8mol
n2 =4-3~=4-(3)(1.1)=0.7mol
n3 = E = 1.1mol
n4 = 2~ = (2)(1.1) = 2.2mol

Therefore, the total number of moles is 4.8 moles and the mole fraction of each
species is
0.8
51 = - = 0.167
4.8
0.7
x2=-- - 0.146
4.8
1.1
23 = - = 0.229
4.8
2.2
q=-= 0.458
4.8
The fractional conversion, X, based on the limiting reactant A2 is
4 - 0.7
x=-- - 0.825
4

Molar concentration of the ith species, 4, is defined by
ni
q=- (5.3-14)
V
Therefore, division of h. (5.3-10) by the volume V gives

(5.3- 15)

(5.3-16)
where q, is the initial molar concentration of the ith species and E is the intensive
mtent of the reaction in moles per unit volume. Note that 5 is related to conversion,
x,
by
(5.3- 1 7)
I I
The total molar concentration, c, of a reacting mixture at any instant can be
calculated by the summation of Eq. (5.3-16) over all species, i.e.,

(5.3-18)