Respuesta :
Answer: If it has a 1/2 life of 14 days, after 14 days there will be half of it left correct?
Explanation:So, how many half-lifes are in 42 days?
42 / 14 = 3
This means it will divide 3 times.
1st half life period: 10 / 2 = 5g
2nd period: 5 / 2 = 2.5g
3rd period: 2.5 / 2 = 1.25g
10 g at start, 5 g at 14 days, 2.5 g at 28 days, 1.25 g at 42 days.
Answer: The amount of substance left will be 0.316 grams.
Explanation:
All the decay processes follow first order kinetics.
The equation used to calculate half life for first order kinetics:
[tex]t_{1/2}=\frac{0.693}{k}[/tex]
where,
[tex]t_{1/2}[/tex] = half life of the reaction = 14 days
k = ?
Putting values in above equation, we get:
[tex]k=\frac{0.693}{14days}=0.0495days^{-1}[/tex]
Rate law expression for first order kinetics is given by the equation:
[tex]t=\frac{2.303}{k}\log\frac{a}{y}[/tex]
where,
k = rate constant = [tex]0.0495days^{-1}[/tex]
t = time taken for decay process = 70 days
a = initial amount of the reactant = 10 grams
y = amount left after decay process = ? grams
Putting values in above equation, we get:
[tex]70days=\frac{2.303}{0.0495days^{-1}}\log\frac{10g}{y}\\\\y=0.316g[/tex]
Hence, the amount of substance left will be 0.316 grams.
