What fraction of a reactant has been consumed after 4 half-lives in a first-order reaction?

Answer 1

For a first order reaction, after

1 half life, there is 0.5 remaining or 0.5 consumed

2 half lives, there is 0.25 remaining or 0.75 consumed

3 half lives, there is 0.125 remaining or 0.875 consumed

4 half lives, there is 0.0625 remaining or 0.9375 consumed

The other way to see this is as follows:

fraction remaining = 0.5ⁿ where n is the number of half lives that have elapsed. So, for 4 half lives you have...

fraction remaining = 0.5⁴ = 0.0625 meaning 0.9375 has been consumed