A substance undergoes first order decomposition. The decomposition follows two parallel first order reaction as: k 1=1.26 × 10-4 s -1 ; k 2=3.8 × 10-5 s -1 The percentage distribution of B and C are

Question

A substance undergoes first order decomposition. The decomposition follows two parallel first order reaction as: <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/chemistry/701bd0b3839e8bca7b2b20327277f8b0-.png" /> k 1=1.26 × 10-4 s -1 ; k 2=3.8 × 10-5 s -1 The percentage distribution of B and C are (A) 75 % B and 25 C (B) 80 % B and 20 % C (C) 90 % B and 10 % C (D) 76.83 % B and 23.1 % C

Tardigrade Admin · Accepted Answer

% of B =( k 1/ k 1+ k 2)=(1.26 × 10-4/1.26 × 10-4+3.8 × 10-5) × 100 =(1.26 × 10-4/10-4(1.26+0.38)) × 100=76.83 % % of C=100-76.83=23.17 %

Q. A substance undergoes first order decomposition. The decomposition follows two parallel first order reaction as:

$k_{1} = 1.26 \times 1 0^{- 4} s^{- 1}; k_{2} = 3.8 \times 1 0^{- 5} s^{- 1}$
The percentage distribution of $B$ and $C$ are

$75% B$ and $25 C$

$80% B$ and $20% C$

$90% B$ and $10% C$

$76.83% B$ and $23.1% C$

$%$ of $B = \frac{k _{1}}{k _{1} + k _{2}} = \frac{1.26 \times 1 0 ^{- 4}}{1.26 \times 1 0 ^{- 4} + 3.8 \times 1 0 ^{- 5}} \times 100$
$= \frac{1.26 \times 1 0 ^{- 4}}{1 0 ^{- 4} ( 1.26 + 0.38 )} \times 100 = 76.83%$
$%$ of $C = 100 - 76.83 = 23.17%$

Q. A substance undergoes first order decomposition. The decomposition follows two parallel first order reaction as: k1​=1.26×10−4s−1;k2​=3.8×10−5s−1 The percentage distribution of B and C are

75%B and 25C

80%B and 20%C

90%B and 10%C

76.83%B and 23.1%C