Page 117 - Elements of Chemical Reaction Engineering 3rd Edition

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See. 3.3 Stoichiclmetric Table

NaOH + (C17 H,,COO),C, H, __j C,,H,,COONa + C, H,(OH),
Choosing a basis
of calculation
A + JB * C + fD
3
We may then perfom the calculations shown in Table E3-4.1. Because this is a liq-
uid-phase reaction, the density p is considered to be constant; therefore, V = V,>.

TABLE E3-4.1. STOICHIOMETRIC TABLE FOR LIQUID-PHASE SOAP REACTION
Species Symbol Initially Change Remaining Concentration

NaOlH

Stoichiometric
. table (batch)

Example 3-5 What Is the Limiting Reactant?

Having set up thle stoichiometric table in Example 3-4, one can now readily use it to
calcullate the concentrations at a given conversion. If the initial mixture consists
solely of sodium hydroxide at a concentration of 10 mol/L (Le., 10 mol/dm3 or 10
kmoil’m3 ) and of glyceryl stearate at a concentration of 2 g mol/L, what is the con-
centration of glycerine when the conversion of sodium hydroxide is (a) 20% ,and
(b) 90%?

Solution
Only the reactants NaOH and (CI7 H3,COO),C, H, are initially present; therefore,
0, = 0, = 0.
(a) For 20% conlversion:

CD = CAo(:] = (10)k) 0.67 g moVL = 0.67 mol/dm3
=

= lO(0.133) = 1.33moVdm3