# How do you calculate the number of sodium ions, Na^+, in 14.2 g of sodium sulfate? [Relative atomic masses Na = 23, S = 32, O = 16]?

Oct 1, 2016

Use the number of moles of sodium per mole of sodium sulfate.

#### Explanation:

Sodium sulfate is $N {a}_{2}$$S {O}_{4}$
First, calculate the moles of sodium sulfate you have in a 14.2g sample.

1. Find the molar mass of sodium sulfate
molar mass = atomic mass in grams
2(23) + 32 + 4(16) = 142 grams per mole
2. Divide the mass of the sample by the molar mass to obtain moles
$\frac{14.2 g}{142 g m o {l}^{-} 1}$ = 0.1 mol

Now, for every 1 mol of $N {a}_{2}$$S {O}_{4}$ you have 2 moles of $N {a}^{+}$ ions. Multiple the moles of $N {a}_{2}$$S {O}_{4}$ that you found just then by 2 to obtain the moles of sodium ions.

Use Avogadro's number (6.022 x ${10}^{23}$) to find the number of ions present. (Recall that Avogrado's number is the number of particles per mole of a substance).

6.022 x ${10}^{23}$ x 0.2 mol = 1.2044 x ${10}^{23}$ ions