Question

Astatine -211 has half a life of seven hours. If u start with 50.0 grams of astatine-211, how much will remain after 28 hours

Answer 1

3.125 grams

Step-by-step explanation:

Applying,

R = (
`2^(t/n)`)R'............... Equation 1

Where R = Original mass of Astatine-211, R' = mass of Astatine-211 left after decay, t = total disintegeration time, n = halflife of Astatine-211

make R' the subject of the equation

R' = R/(
`2^(t/n)`)............ Equation 2

From the question,

Given: R = 50 grams, t = 28 hours, n = 7 hours

Substitute into equation 2

R' = 50/(
`2^(28/7)`)

R' = 50/(2⁴)

R' = 50/16

R' = 3.125 grams