The concentration of Rn−222 in the basement of a house is 1.45 × 10−6 mol/L. Assume the air remains static and calculate the concentration of the radon after 3.00 days. The half-life of Rn−222 is 3.82 days.

Respuesta :

Answer: The concentration of radon after the given time is [tex]3.83\times 10^{-30}mol/L[/tex]

Explanation:

All the radioactive reactions follows first order kinetics.

The equation used to calculate half life for first order kinetics:

[tex]t_{1/2}=\frac{0.693}{k}[/tex]

We are given:

[tex]t_{1/2}=3.82days[/tex]

Putting values in above equation, we get:

[tex]k=\frac{0.693}{3.82}=0.181days^{-1}[/tex]

Rate law expression for first order kinetics is given by the equation:

[tex]k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}[/tex]

where,  

k = rate constant = [tex]0.181days^{-1}[/tex]

t = time taken for decay process = 3.00 days

[tex][A_o][/tex] = initial amount of the reactant = [tex]1.45\times 10^{-6}mol/L[/tex]

[A] = amount left after decay process =  ?

Putting values in above equation, we get:

[tex]0.181days^{-1}=\frac{2.303}{3.00days}\log\frac{1.45\times 10^{-6}}{[A]}[/tex]

[tex][A]=3.83\times 10^{-30}mol/L[/tex]

Hence, the concentration of radon after the given time is [tex]3.83\times 10^{-30}mol/L[/tex]