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:

After 18 hours, the amount of pure technetium that will be remaining is 12.5 grams

Explanation:

To solve the question, we note that the equation for half life is as follows;

$N(t) = N_0 (\frac{1}{2} )^{\frac{t}{t_{1/2}}$

Where:

N(t) = Quantity of the remaining substance  = Required quantity

N₀ = Initial radioactive substance quantity  = 100 g

t = Time duration  = 18 hours

${t_{1/2}$ = Half life of the radioactive substance  = 6 hours

Therefore, plugging in the values, we have;

$N(t) = 100 (\frac{1}{2} )^{\frac{18}{6}} = 100 (\frac{1}{2} )^{3} = \frac{100 }{8} = 12.5 \ grams$

Therefore, after 18 hours, the amount of pure technetium that will be remaining = 12.5 grams.