Question

Urea (NH₂CONH₂) is the end product in protein metabolism in animals. The decomposition of urea in 0.1 M HCl occurs according to the reaction: NH₂CONH₂(aq) + H⁺(aq) + 2H₂O(l) → 2 NH₄⁺(aq) + HCO₃⁻(aq). The reaction is first order in urea and first order overall. When [NH₂CONH₂]= 0.200 M, the rate at 61.05 °C is 8.56 x 10⁻⁵ M/s.

What is the rate constant?

a. 8.56 x 10⁻⁵ s⁻¹
b. 1.23 x 10⁻³ s⁻¹
c. 5.67 x 10⁻⁷ s⁻¹
d. 2.34 x 10⁻⁴ s⁻¹

Answer 1

The rate constant for the decomposition of urea in the given reaction is calculated using the rate law equation. However, the calculated value (4.28 x 10⁻⁴ s⁻ⁱ) does not exactly match the options given, suggesting the closest correct option is likely 2.34 x 10⁻⁴ s⁻ⁱ.

Step-by-step explanation:

The question requires the determination of the rate constant for the decomposition of urea in an acidic solution. The reaction is given to be first order in urea and first order overall. Since the reaction order is one, the rate law can be expressed as Rate = k[NH₂CONH₂]. We are given that the rate is 8.56 x 10⁻⁵ M/s when the concentration of urea is 0.200 M.

To find the rate constant k, we use the rate law equation:

Rate = k[NH₂CONH₂]

8.56 x 10⁻⁵ M/s = k(0.200 M)

k = (8.56 x 10⁻⁵ M/s) / (0.200 M)

k = 4.28 x 10⁻⁴ s⁻ⁱ

This value is not listed in the choices provided, indicating a possible typo or error in the question or answer choices. If we are to choose from the closest available option, 2.34 x 10⁻⁴ s⁻ⁱ would likely be the intended correct rate constant.