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# rate constant? ?

A reactant decomposes with a half-life of 21.7 s when its initial concentration is 0.379 M. When the initial concentration is 1.25 M, this same reactant decomposes with a half‑life of 71.5 s. ( 0 Order reaction)

What is the value and unit of the rate constant for this reaction?

### 1 Answer

Relevance

- micatkieLv 72 months ago
When the initial concentration is 0.379 M, rate = (0.379/2 M) / (21.7 s) = 0.00873 M/s

When the initial concentration is 1.25 M, rate = (1.25/2 M) / (71.5 s) = 0.00874 M/s

No matter what the initial concentration is, the rate is constant.

Hence, it is a zero-order reaction, and thus Rate = k

The value of the rate constant, k, is 0.00874 in M/s.

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