Question

Calculate the mass in grams of a sample of Bi containing 7.35 x1023 atoms.Write your answer using three significant figures.

Answer 1

The mass in grams of the sample is 254.956g

- First, we need to know how many moles of Bi are represented in 7.35x10^23 atoms. So, we use the Avogadro's number (6.022x10^23) to make that calculation:

$\frac{7.35x10^{23}atoms.1mol}{6.022x10^{23}\text{atoms}}=1.22\text{ mol}$

Now, we know that 1.22 moles of Bi have 7.35x10^23 atoms.

- As the molar mass of bismuth (Bi) is 208.98 g/mol we calculate the mass in grams:

$\frac{1.22\text{mol . 208.98g}}{1\text{mol}}=254.956\text{ g}$

So, the mass in grams of the sample is 254.956g (using three significant figures).