Answer to Question #150668 in Organic Chemistry for Peter

Question

Tc-99 is used by hospitals for brain scans. Tc-99 has a half life of 6 hours. If 400 grams of technetium-99 is injected into you, how much remains when you are released from the hospital 18 hours later

Answer 1

The general formula is:

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

where N(t) is the amount at given time, N₀ is the initial amount, t is the given time and t_1/2 is the half-life.

Therefore,

$N(18hrs)=400g(\frac{1}{2})^{\frac{18}{6}}=50.0g$

Answer: 50.0 g