Question

At a certain temperature this reaction follows first-order kinetics with a rate constant of 0.086 s^-1:

2H3PO4(aq)=P2O5(aq)+3H2O(aq)

Suppose a vessel contains H3PO4 at a concentration of 1.27 M . Calculate how long it takes for the concentration of H3PO4 to decrease to 7.0% of its initial value. You may assume no other reaction is important.

Round your answer to 2 significant digits.

Please, need this ASAP

Answer 1

It takes 31 s for 1.27 M H₃PO₄ to decrease its concentration to 7.0% of its initial value following first-order kinetics.

What is first-order kinetics?

First-order kinetics occur when a constant proportion of a reactant disappears per unit time.

Let's consider the following first-order kinetics reaction with a rate constant k = 0.086 s⁻¹.

2 H₃PO₄(aq) = P₂O₅(aq) + 3 H₂O(aq)

Given the initial concentation is [H₃PO₄]₀ = 1.27 M, the concentration representing 7.0% of this value is:

[H₃PO₄] = 7.0% × 1.27 M = 0.089 M

We can calculate the time elapsed (t) using the following expression.

ln ([H₃PO₄]/[H₃PO₄]₀) = - k × t

ln (0.089 M/1.27 M) = - 0.086 s⁻¹ × t

t = 31 s

It takes 31 s for 1.27 M H₃PO₄ to decrease its concentration to 7.0% of its initial value following first-order kinetics.

Learn more about first-order kinetics here: https://brainly.com/question/18916637

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