A reaction is of first order when — Chemical Kinetics Chemistry Question

💡 Solution & Explanation

I need to explain the characteristics of a first-order reaction, but I notice the options (A, B, D) aren't provided in your question. I'll explain the defining feature of a first-order reaction: **A first-order reaction is characterized by:** The rate of reaction depends on the **first power of concentration** of one reactant (or the sum of exponents equals 1). **Mathematical definition:** $$\text{Rate} = k[A]^1 = k[A]$$ where $k$ is the rate constant and $[A]$ is the concentration of reactant. **Key characteristics:** 1. **Half-life is constant** — independent of initial concentration 2. **Integrated rate law:** $\ln[A] = -kt + \ln[A]_0$ (linear when plotting $\ln[A]$ vs. time) 3. **Units of $k$:** $\text{s}^{-1}$ or $\text{min}^{-1}$ (time$^{-1}$) 4. **Rate depends linearly on concentration** — doubling $[A]$ doubles the rate **Without seeing option C**, the correct answer typically states: *"the rate is directly proportional to the first power of the concentration of reactant"* OR *"the half-life is independent of the initial concentration"* OR *"a plot of $\ln(\text{concentration})$ vs. time is linear"* If you provide the options, I can confirm which specific statement defines option C correctly.