Half-Life Calculations-More Practice

Front

What is Half-Life?

Back

Half-Life is the time required for half of the radioactive atoms in a sample to decay.

Front

How do you calculate the remaining amount of a substance after a certain number of half-lives?

Back

Remaining Amount = Initial Amount × (1/2)^(number of half-lives)

Front

If the half-life of an isotope is 3 days, how much of a 100g sample remains after 6 days?

Back

25g remains after 6 days (2 half-lives).

Front

What percentage of a radioactive isotope remains after 1 half-life?

Back

50% of the original amount remains after 1 half-life.

Front

What percentage of a radioactive isotope remains after 2 half-lives?

Back

25% of the original amount remains after 2 half-lives.

Front

What is the half-life of an isotope if 12.5% remains after 3 half-lives?

Back

The half-life is the time it takes for the amount to reduce to half, which can be calculated from the remaining percentage.

Front

If an isotope has a half-life of 10 seconds, how much of a 40g sample remains after 30 seconds?

Back

5g remains after 30 seconds (3 half-lives).

Front

What is the formula to find the initial amount needed if you know the final amount and the half-life?

Back

Initial Amount = Final Amount / (1/2)^(number of half-lives)