What is the rate constant of a first-order reaction when 20.0% of a reactant remains after 73.5 s?

Half-lives of first order reactions

Explanation:

Notice the the half-life is independent of initial concentration. This is not the case with other reaction orders. The half-life of a first-order reaction was found to be 10 min at a certain temperature. hope this helps you :)

in the given question, the partial pressure is calculated by using the ideal gas equation, that is, pv = nrt

here, p is pressure, v is volume = 25 l, n is number of moles = 0.0104 moles, r is gas constant = -0.0821 l.atm / mol.k

t is temperature = 273 k

p = nrt / v

p = (0.0104 mol × 0.0821 l.atm / mol.k × 273 k) / 25 l

= 0.0093 atm