PLEASE HELP!!!! THANK YOU SO MUCH A certain first-order reaction (Arightarrowpro

Question

PLEASE HELP!!!! THANK YOU SO MUCH

A certain first-order reaction (Arightarrowproducts) has a rate constant of 1.00times10^-2 s^-1 at 45 degreeC. How many minutes does it take for the concentration of the reactant, [A], to drop to 6.25% of the original concentration? Express your answer with the appropriate units. A certain second-order reaction (Brightarrowproducts) has a rate constant of 1.55times10^-3 M^-1 s^-1 at 27 degreeC and an initial half-life of 252 s. What is the concentration of the reactant B after one half-life? Express your answer with the appropriate units.

Explanation / Answer

rate equation for the first order

rate constant k = 2.303/ t x log [A0/A]

where A0 = intial concentration = 100%

A is the concentration after certain time = 6.25%

K = rate constant = 1.0 x 10-2 s-1

1.0 x 10-2 = 2.303 / t log [100 / 6.25]

t = 2.773 / 0.01

t = 277.3 s

partB

t1/2 = 1 / k [A]

252 = 1/ 1.55 x 10-3 x [A]

[A] = 2.56 M

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