Half-Life Calculations and Concepts

Max explains the concept of half-lives, which describe the rate of decay for radioactive elements. He provides a detailed explanation of how to solve problems involving half-lives through three practice problems. The first problem involves calculating the remaining mass of Caesium-137 after a certain period. The second problem focuses on determining the age of a Carbon-14 sample. The third problem involves finding the half-life of a substance given initial and final masses. Each problem is solved step-by-step, emphasizing the importance of defining variables and using the correct equations.

What is the primary purpose of understanding half-lives in radioactive elements?

• To stop the decay process

• To measure the speed of decay

• To create new elements

• To increase the decay rate

How is a half-life denoted in scientific terms?

• T full

• T one half

• T zero

• T double

In the cesium-137 problem, what is the initial mass of the sample?

• 0.25 kilograms

• 2.00 kilograms

• 1.00 kilograms

• 0.5 kilograms

How many half-lives does cesium-137 undergo in 151 years?

• Six

• Three

• Four

• Five

What is the final mass of the sample in the cesium-137 problem after 151 years?

• 0.03125 kilograms

• 0.0625 kilograms

• 0.125 kilograms

• 0.25 kilograms

What is the half-life of carbon-14 as mentioned in the practice problem?

• 57300 years

• 573000 years

• 573 years

• 5730 years

How many times do you need to divide 24 grams by 2 to reach 1.5 grams in the carbon-14 problem?

• Three times

• Two times

• Four times

• Five times

In the third practice problem, what is the initial mass of the sample?

• 32 grams

• 16 grams

• 8 grams

• 64 grams

How many half-lives are needed to reduce 64 grams to 2 grams?

• Three

• Five

• Four

• Six

What is the calculated half-life duration in the third practice problem?

• 3.5 hours

• 4.5 hours

• 2.5 hours

• 1.5 hours