Compute the number of ions present in 5.85 g of sodium chloride?

The formula unit mass of sodium chloride (NaCl) is

= 1 X atomic mass of sodium + 1 X atomic mass of chlorine

= 1 X 23 + 1 X 35.5

= 58.5u

So, 58.5g of sodium chloride will consist of 6.022 X 10²³ ions of sodium and 6.022 X 10²³ ions of chlorine. Thus

58.5g of NaCl = 6.022 X 10²³ ions of sodium

1g of NaCl = (6.022 X 10²³ / 58.5) ions of sodium

5.85g of NaCl = (6.022 X 10²³ X 5.85) / 58.5 ions of sodium

= 6.022 X 10²² ions of sodium