Calculate the initial mass of A given that 2.77g of A remains after 1.66min

Question

The rate constant for this first order reaction is 0.0176s^-1 at 300 degrees C

Answer 1

There are several ways to approach the problem. I think the easiest is to find the half life then the mass for a first order reaction is

t1/2 = 0.693/k0.0176 = 39.38 sec

1.66 min = 99.6 sec = 99.6/39.38 = 2.53 half lives

fraction remaining = 0.5ⁿ where = #half lives = 2.53

fraction remaining = 0.5^2.53 = 0.17

0.17x = 2.7 g

x = 15.9;g