A) Order of reaction: The order of reaction with respect to a reactant is the exponent to which its concentration term is raised in the rate law. It indicates how the rate of reaction is affecte
This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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e)
i)
A) Order of reaction: The order of reaction with respect to a reactant is the exponent to which its concentration term is raised in the rate law. It indicates how the rate of reaction is affected by a change in the concentration of that specific reactant. The overall order of reaction is the sum of the orders with respect to all reactants.
B) Instantaneous reaction rate: This is the rate of a chemical reaction at a particular moment in time. It is determined by calculating the slope of the tangent to the concentration-time curve at that specific time.
ii) Determine the half-life of the reaction:
The half-life ($t_{1/2}$) is the time required for the concentration of a reactant to decrease to half of its initial value.
Let's examine the data:
From $[A] = 0.40 \text{ mol dm}^{-3}$ (at $t = 8 \times 10^3 \text{ s}$) to $[A] = 0.20 \text{ mol dm}^{-3}$ (at $t = 16 \times 10^3 \text{ s}$).
The concentration has halved. The time taken is $(16 - 8) \times 10^3 \text{ s} = 8 \times 10^3 \text{ s}$.
From $[A] = 0.28 \text{ mol dm}^{-3}$ (at $t = 12 \times 10^3 \text{ s}$) to $[A] = 0.14 \text{ mol dm}^{-3}$ (at $t = 20 \times 10^3 \text{ s}$).
The concentration has halved. The time taken is $(20 - 12) \times 10^3 \text{ s} = 8 \times 10^3 \text{ s}$.
From $[A] = 0.58 \text{ mol dm}^{-3}$ (at $t = 4 \times 10^3 \text{ s}$), half of this is $0.29 \text{ mol dm}^{-3}$. This value is very close to $0.28 \text{ mol dm}^{-3}$ at $t = 12 \times 10^3 \text{ s}$. The time taken is approximately $(12 - 4) \times 10^3 \text{ s} = 8 \times 10^3 \text{ s}$.
Since the half-life is constant, the reaction is first order.
The half-life of the reaction is $\boxed{8 \times 10^3 \text{ s}}$.
iii) Determine the order of the reaction with respect to A:
As observed in part (ii), the half-life of the reaction is constant and independent of the initial concentration of A. This is a characteristic property of a first-order reaction.
Therefore, the order of the reaction with respect to A is $\boxed{first order}$.
d) Define an acid according to Brønsted and Lowry:
According to the Brønsted-Lowry theory, an acid is a proton donor. It is a chemical species that donates a hydrogen ion ($\text{H}^+$) to another substance in a chemical reaction.
