Half-Life Calculations and Concepts

The video tutorial explains how to solve half-life problems using different methods, including the box method, formulas, and common sense. It covers calculating the number of half-lives, finding the fraction of a sample remaining, and determining the mass remaining after a given time. The tutorial uses chromium-51 as an example to demonstrate these calculations and also explains how to work backward to find the original mass of a sample.

Which method can be used to solve half-life problems if you prefer not to use formulas?

• Guessing

• Trial and error

• Box method

• Graphical method

What do you need to calculate the number of half-lives a sample has undergone?

• Temperature and pressure

• Decay constant and initial concentration

• Total time elapsed and time for one half-life

• Initial mass and final mass

How do you find the fraction of a sample remaining after a certain number of half-lives?

• Divide the number of half-lives by 2

• Multiply the number of half-lives by 2

• Raise 1/2 to the power of the number of half-lives

• Subtract the number of half-lives from 1

If a sample has undergone three half-lives, what fraction of the original sample remains?

• 1/10

• 1/8

• 1/6

• 1/4

What is the half-life of chromium-51 as mentioned in the sample problem?

• 84 days

• 56 days

• 28 days

• 14 days

After six half-lives, what fraction of the original sample remains?

• 1/16

• 1/32

• 1/64

• 1/128

How do you calculate the remaining mass of a sample after a certain number of half-lives?

• Multiply the original mass by the fraction remaining

• Add the original mass to the fraction remaining

• Divide the original mass by the fraction remaining

• Subtract the fraction remaining from the original mass

What is the remaining mass of a 52-gram sample after six half-lives?

• 0.8125 grams

• 3.125 grams

• 2.5 grams

• 1.625 grams

How do you determine the original mass of a sample if you know the remaining mass after a certain number of half-lives?

• Multiply the remaining mass by the number of half-lives

• Divide the remaining mass by the number of half-lives

• Double the remaining mass for each half-life

• Subtract the remaining mass from the original mass

If 0.75 milligrams remain after six half-lives, what was the original mass?

• 60 milligrams

• 48 milligrams

• 36 milligrams

• 24 milligrams