1 Marks Question

Question 11 Mark

For a reaction, A + B → Product; the rate law is given by, r = k [ A]^1/2 [B]². What is the order of the reaction?

Answer

The order of the reaction is sum of the powers on concentration.
So that sum will.
r = k [A]^1/2[B]²
Order of reaction = 12 + 2 = 2.5.12 + 2 = 2.5.

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Question 21 Mark

In a reaction, 2A → Products, the concentration of A decreases from 0.5 mol L^–1 to 0.4 mol L^–1 in 10 minutes. Calculate the rate during this interval?

Answer

$\text{Average Rate}=\frac{-1}{2}\frac{\triangle\ [\text{A}]}{\triangle\ \text{t}}=\frac{-1}{2}\frac{\text{[A]}_2-\text{[A]}}{\text{t}_2-\text{t}_1}$
$=\frac{-1}{2}\frac{(0.4-0.5)}{10}=\frac{-1}{2}\frac{(-0.1)}{10}$
= 5 × 10^-3 M min^-1

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Question 31 Mark

For the reaction R → P, the concentration of a reactant changes from 0.03M to 0.02M in 25 minutes. Calculate the average rate of reaction using units of time both in minutes and seconds.

Answer

Average rate of reaction
$=-\frac{\triangle[\text{R}]}{\triangle\text{t}}$
$=-\frac{[\text{R}]_2-[\text{R}]_1}{\text{t}_2-\text{t}_1}$
$=-\frac{0.02-0.03}{25}\text{M mim}^{-1}$
$=-\frac{-0.01}{25}\text{M mim}^{-1}$
= 4 × 10^-4 M min^-1
^{$=\frac{4\times10^{-4}}{60}\text{M s}^{-1}$}
= 6.67 × 10^-6 Ms^-1

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Question 41 Mark

Define 'order of a reaction'.

Answer

The sum of powers of the concentration terms of the reactants in the rate law expression is called the order of that chemical reaction.

Alternate answer

rate = k[A]^P [B]^q
Order of reaction = P+q.

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Question 51 Mark

Write the differential velocity equation for the reaction 2A+B→ Product.

Answer

Rate $=-\frac{1}{2} \frac{d[A]}{d t}=-\frac{d[B]}{d t}$