Question

Please help me, I'm stuck and I don't know how to do it.

How many atoms are there in 7.02 g Si ?

Answer 1

Answer:

1.51e23 atoms

Explanation:

First, using the molar mass of Si (28.1 g/mol), determine the # of moles of Si we have. Then use Avogadro's number (6.022e23 atoms = 1 mol) to convert the # of moles to the # of Si atoms.

(7.02 g Si)($\frac{1 mol}{28.1 g}$) = 0.250 mol Si              

(0.250 mol Si)($\frac{6.022*10^{23} atoms }{1 mol}$) = 1.51e23 atoms