Question

The isotope chromium-51 has a half-life of 28 days. If the original sample had a mass of 28.0 grams, what mass of the chromium-51 sample remains after 84 days?

Answer 1

`3.50g`

Explanation:

To find the mass of the chronium-51 sample that remains after `84` days, we can use the half-life formula.

Recall the half-life formula:

`color(blue)(|bar(ul(color(white)(a/a)A=A_0(1/2)^(t/h)color(white)(a/a)|)))`

where:
`A=`final amount
`A_0=`initial amount
`t=`time elapsed
`h=`time for half of initial amount to remain after decay (also known as half-life)

Plugging in our known values,

`A=28.0g(1/2)^((84color(white)(i)"days")/(28color(white)(i)"days"))`

`A=color(green)(|bar(ul(color(white)(a/a)color(black)(3.50g)color(white)(a/a)|)))`