Question

the atomic mass of calcium is 40.08. what is the mass of 6.02×10²³ atoms of calcium?

a. 40.08 kg
b. 400.8 g
c. 40.08 g
d. 6.02 kg
e. 6.02 g

Explanation:

Step1: Recall Avogadro's number

1 mole of any substance contains $6.02\times 10^{23}$ particles.

Step2: Relate atomic mass and molar mass

The atomic mass of calcium is 40.08 u. The molar mass of calcium has the same numerical value as the atomic mass but in grams per mole. So, the molar mass of calcium $M = 40.08\ g/mol$.

Step3: Calculate the mass

If $N = 6.02\times 10^{23}$ atoms of calcium, this is 1 mole of calcium. The mass $m$ of 1 - mole of calcium is equal to its molar mass. So, $m=40.08\ g$.

Answer:

C. 40.08 g