Consider the below chemical reaction that occurs via first-order kinetics with a rate constant of 5.12 x 10–3 s–1 at a particular temperature. how long will it take for 30% of substrate a to be consumed? a → b 83.7 s

- Answer is 69.7 second.

Solution:- For solving problems based on first order equations is:

where, is the initial concentration and [A] is final concentration.

k is rate constant and t is the time.

It asks to calculate the time in which 30% of the substrate would be consumed. Let's say the initial amount of the substrate is 100 then 30 is used and remaining would be, 100 - 30 = 70

So, = 100

[A] = 70

t = ?

Let's plug in the values in the equation and solve it for t:

4.248 = -0.00512(t) + 4.605

4.248 - 4.605 = -0.00512(t)

-0.357 = -0.00512(t)

we have negative sign on both sides, so it is canceled out.

0.357 = 0.00512(t)

t = 69.7 seconds

So, it would take 69.7 seconds for 30% substrate to be consumed.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.