Question

How many grams of rubidium are in 2.39 x 1024 atoms of rubidium? the answer i put in for this question was wrong

Answer 1

Answer:

339 g of Rb.

Explanation:

First, we have to convert 2.39 x 10²⁴ atoms of rubidium (Rb) using Avogadro's number which is 6.022 x 10²³ atoms/mol. The conversion will look like this:

$2.39\cdot10^{24}\text{ atoms Rb}\cdot\frac{1\text{ mol}}{6.022\cdot10^{23}\text{ atoms}}=3.968\text{ moles Rb}\approx3.97\text{ moles Rb,}$

and now, let's convert this to grams using the molar mass of Rb which is 85.5 g/mol:

$3.97\text{ moles Rb}\cdot\frac{85.5\text{ g Rb}}{1\text{ mol Rb}}=339.4\text{ g Rb}\approx339\text{ g Rb.}$

With correct significant figures (3 significant figures), the answer would be 339 g of Rb.