The reactant concentration in a first-order reaction was 7.30 × 10^(-2) M after 25.0 s and 9.50 × 10^(-3) M after 95.0 s. What is the rate constant for this reaction?

For the reaction A →  B, the rate constant is 0.0837 M^–1•sec^–1. How long would it take for [A] to decrease by 85%?

The following reaction has a rate constant of 3.7 × 10^–3 M•s^–1 at 25°C:

A → B + C

Calculate the concentration of C after 2.7 × 10^–3 sec where [A]₀ was 0.750 M at 25°C; assume [C]₀ = 0 M.

For the decomposition of urea, NH₂CONH₂ (aq) + H⁺(aq) + 2 H₂O (l) → 2 NH₄⁺ (aq) + HCO₃^– (aq), the rate constant is 3.24 × 10^–4 s^–1 at 35°C. The initial concentration of urea is 2.89 mol/L. What fraction of urea has decomposed after 3.5 minutes?