Answer :
Answer:
In this problem, we need to determine the concentrations of A and B to achieve a mole ratio of 100:1 and calculate the initial concentration of D required for the reaction.
Given:
Mixture consists of 90 mole% A (45 mol/liter) and 10 mole% B (5 mol/liter)
Desired mole ratio of A to B is 100:1
Reactions: A + D → R and B + D → S
Reaction rates: -rA = 21CACD and -rB = 147CBCD
Step 1: Determine the concentrations of A and B to achieve a mole ratio of 100:1.
Let the concentration of B be x mol/liter.
Then, the concentration of A will be 100x mol/liter.
Total concentration = Concentration of A + Concentration of B
50 mol/liter = 100x + x
50 mol/liter = 101x
x = 50/101 ≈ 0.495 mol/liter
Concentration of A = 100 × 0.495 ≈ 49.5 mol/liter
Concentration of B ≈ 0.495 mol/liter
Step 2: Calculate the initial concentration of D required for the reaction.
We can use the reaction rate equations to determine the concentration of D.
-rA = 21CACD
-rB = 147CBCD
Since both reactions consume D, we can equate the reaction rates:
-rA = -rB
21CACD = 147CBCD
Substitute the concentrations of A and B:
21 × 49.5 × CD = 147 × 0.495 × CD
1039.5CD = 72.765CD
CD = 72.765/1039.5 ≈ 0.07 mol/liter
Therefore, the initial concentration of D should be approximately 0.07 mol/liter.