Question

223Ra decays by alpha emission with a half-life of 11.43 days. For a 1.0g sample of 223Ra, after one half-life, what mass of 223Ra remains? What has happened to the remaining mass?

Answer 1

Explanation:

The reaction that shows the alpha decay of $^{223}_{88}Ra$ is:

$^{223}_{88}Ra\rightarrow ^{219}_{86}Rn+^{4}_{2}He$

Half life is the time at which the concentration of the reactant reduced to half. So,

$Mass\ of\ ^{223}_{88}Ra\ remained=\frac {Initial\ concentration}{2}=\frac {1.0\ g}{2}=0.5\ g$

The remaining mass is converted to $^{219}_{86}Rn$.