Half-Life Calculations

Question

The half-life of Ruthenium-97 is approximately three days. If a 450 g sample of the compound is left to decay during the month of April, how much of the compound will be left? Round your answer to two decimal places and write a word answer, including units.

Answer 1

Fraction remaining = 0.5ⁿ where n is the number of half lives that have elapsed

n = 30 days/3 days = ~10 half lives have elapsed

fraction remaining = ?

fraction remaining = 0.5¹⁰ = 0.0009766

amount remaining = 450 g x 0.0009766 = 0.439 g = 0.44 g (rounded to 2 decimal places)

After one month (April) containing 30 days, there will be 0.44 g of ruthenium left.