What is the age of a sample if there are 6 grams of an element that have not decayed out an original 24 grams and has a half-life of 8yrs. a. 8yrs b. 50yrs c. 29yrs d. 16yrs

Respuesta :

Answer:

16 years is the age of a sample.

Explanation:

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

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

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

where,  

k = rate constant 

[tex]t_{1/2}[/tex]= half life of the sample

t = time taken for decay process

[tex][A_o][/tex] = initial amount of the sample

[A] = amount left after decay process 

We are given:

[tex][A_o][/tex] = 24 grams

[A] = 6 grams

[tex]t_{1/2}= 8 years[/tex]

Putting values in above equation, we get:

[tex]k=\frac{0.693}{8 years}=0.086625 year^{-1}[/tex]

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

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

On substituting the values we get value of t:

t = 16.00 years

16 years is the age of a sample.