95.2k views
4 votes
The reactant concentration in a first-order reaction was 8.10×10−2 M M after 15.0 s s and 1.80×10−3 M M after 90.0 s s . What is the rate constant for this reaction?

User Urish
by
5.6k points

1 Answer

5 votes

Answer:

The answer to the question is

The rate constant for the reaction is 1.056×10⁻³ M/s

Step-by-step explanation:

To solve the question, e note that

For a zero order reaction, the rate law is given by

[A] = -k×t + [A]₀

This can be represented by the linear equation y = mx + c

Such that y = [A], m which is the gradient is = -k, and the intercept c = [A]₀

Therefore the rate constant k which is the gradient is given by

Gradient =
([A]_(2) - [A]_(1) )/(t_(2) - t_(1) ) where [A]₁ = 8.10×10⁻² M and [A]₂ = 1.80×10⁻³ M

=
(1.80*10^(-3) M- 8.10*10^(-2) M)/(90 s - 15 s) = -0.001056 M/s = -1.056×10⁻³ M/s

Threfore k = 1.056×10⁻³ M/s

User Stephen Pham
by
6.1k points