228k views
5 votes
Leutium-176 has a half-life of 3.85 mc012-1.jpg 1010 years. After 1.155 mc012-2.jpg 1011 years, how much leutium-176 will remain from an original 16.8-g sample?

2.10 g
3.00 g
5.56 g
8.40 g

2 Answers

3 votes

Answer:

A.

Step-by-step explanation:

User Nellute
by
6.8k points
4 votes

Answer : The amount left of leutium-176 will be, 2.10 g

Solution :

First we have to calculate the rate constant, we use the formula :


k=(0.693)/(t_(1/2))


k=\frac{0.693}{3.85* 10^(10)\text{years}}


k=0.18* 10^(-10)\text{years}^(-1)

Now we have to calculate the amount left of the sample.

Expression for rate law for first order kinetics is given by :


t=(2.303)/(k)\log(a)/(a-x)

where,

k = rate constant =
0.18* 10^(-10)\text{years}^(-1)

t = decay time =
1.155* 10^(11)\text{ years}

a = initial amount of the sample = 16.8 g

a - x = amount left after decay process = ?

Now put all the given values in above equation, we get


1.155* 10^(11)\text{years}=\frac{2.303}{0.18* 10^(-10)\text{years}^(-1)}\log(16.8)/(a-x)


a-x=2.10g

Therefore, the amount left of leutium-176 will be, 2.10 g

User Machtyn
by
6.8k points