Compute the number of ions present in 5.85 g of sodium chloride.
The molar mass of NaCl = The atomic weight of Na + The atomic weight of Cl
Atomic weight; Na = 22.99 g, Cl = 35.45 g
Thus, molar mass of NaCl = 23 + 35.5 = 58.5g/mole.
The number of moles = 
Each NaCl particle contains one Na+ and one Cl– ion = 2 ions
Total moles of ions = 0.1 × 2 = 0.2 moles
Number of ions = total number of moles of ions X Avogadro's number
Therefore,
No. of ions = 0.2 × 6.022 ×1023
= 1.2042 ×1023 ions
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