Question

Technetium has a half-life of six hours. If you obtain 100g of a pure technetium sample, after 18 hours how much of the pure substance will be remaining?

Answer 1

Answer: 12.5 grams.

Explanation:

You can find the amount of pure substance remaining by using the half-life formula:

$Q_{1}=Q(\frac{1}{2})^{\frac{t}{t2} }$

Where t is the amount of time, and t2 is the half life of the substance.

Substituting our values for the variables, we get this equation:

$Q_{1} = 100(\frac{1}{2})^3\\\\Q_{1} = 100(\frac{1}{8})\\\\Q_{1} = 12.5$

After 18 hours, there will be 12.5 grams of the substance remaining.