The reaction ${C H}_{3} - {C H}_{2} - {N O}_{2} + {O H}^{-} ⟶ {C H}_{3} - C H - {N O}_{2} + H_{2} O$ obeys the rate law for pseudo first-order kinetics in the presence of a large excess of hydroxide ion. If 1% of nitroethane undergoes reaction in half a minute when the reactant concentration is 0.002 M. What is the pseudo-first-order rate constant? (log 99 = 1.996)

Open in App

Solution

$C H_{3} - C H_{2} - N O_{2} + O H^{-} ⟶ C H_{3} - C H - N O_{2} + H_{2} O$
$P x^{n}$ in first order w.r.t $C H_{3} - C H_{2} - N O_{2}$
$∴ r = R [C H_{3} - C H_{2} - N O_{2}]$
Rate law equation
$- R \times t = \frac{l n [C H_{3} - C H_{2} - N O_{2}]_{t}}{[C H_{3} -]_{0}}$
$\Rightarrow - R \times 30 = l n (\frac{99 % o f i n i t i a l}{i n i t i a l})$
$\Rightarrow - R \times 30 = ln (\frac{99}{100})$
$\Rightarrow + R \times 30 = (2 - 1.99 %)$
$\Rightarrow R = \frac{0.004}{30} = \frac{4}{3} \times 10^{- 4}$
$= 1.33 \times 10^{- 4} 8^{- 1}$

Suggest Corrections

Similar questions

Q. The reaction

{C H}_{3} - {C H}_{2} - {N O}_{2} + {O H}^{-} ⟶ {C H}_{3} - \oplus C H - {N O}_{2} + H_{2} O

obeys the rate law for pseudo-first-order kinetics in the presence of a large excess of hydroxide ion. If

1

% of nitroethane undergoes reaction in half a minute when the reactant concentration is

0.002 M

. What is the pseudo-first-order rate constant?
(

log 99 = 1.996

)

Q. The reaction

C H_{3} - C H_{2} - N O_{2} + O H^{-} \to C H_{3} - C H - N O_{2} + H_{2} O

obeys the rate law for pseudo first order kinetics in the presence of a large excess of hydroxide ion. If 1 percent of nitro ethane undergoes reaction in half a minute when the reactant concentration is

0.002 M

, the pseudo first order rate constant is :

The value of rate constant of a pseudo first order reaction ..... .
(a) depends on the concentration of reactants present in small amount.
(b) depends on the concentration of reactants present in excess
(c) is independent of the concentration of reactants
(d) depends only on temperature

Q. Which order reaction obeys the expression

t_{1 / 2} = \frac{1}{k . a}

in chemical kinetics?

(

a

= concentration of reactant,

k

= rate constant,

t_{1 / 2}

= half-life)

Q. The value of rate constant of a pseudo first order reaction

Join BYJU'S Learning Program

CH3−CH2−NO2+OH−⟶CH3−CH−NO2+H2OPxn in first order w.r.t CH3−CH2−NO2∴r=R[CH3−CH2−NO2]Rate law equation−R×t=ln[CH3−CH2−NO2]t[CH3−]0⇒−R×30=ln(99%ofinitialinitial)⇒−R×30=ln(99100)⇒+R×30=(2−1.99%)⇒R=0.00430=43×10−4=1.33×10−48−1