Question

How many grams of NaCl equal a mole of NaCI?

Answer 1

`"58.44247 g"`

Explanation:

The problem essentially wants you to find the molar mass of sodium chloride, `"NaCl"`. As you know, the molar mass of an ionic compound gives you the mass of one mole of formula units of that compound.

Now, as given by the compound's chemical formula, one formula unit of sodium chloride contains

• one sodium cation, `1 xx "Na"^(+)`
• one chloride anion, `1 xx "Cl"^(-)`

This means that the mass of one mole of formula units will be equal to the sum of the mass of one mole of sodium cations and the mass of one mole of chloride anions.

Since the mass of an ion is basically the same as the mass of the neutral atom, you can say that the molar mass of sodium chloride will be equal to the sum of the molar mass of sodium, `"Na"`, and the molar mass of chlorine, `"Cl"`.

As given in the Periodic Table of Elements, these are equal to

`M_("M Na") = "22.98977 g mol"^(-1)`

`M_("MCl") = "35.4527 g mol"^(-1)`

You thus have

`M_("M NaCl") = "22.98977 g mol"^(-1) + "35.4527 g mol"^(-1)`

`M_("M NaCl") = "58.44247 g mol"^(-1)`

This means that the mass of one mole of sodium chloride is equal to

`color(green)(|bar(ul(color(white)(a/a)color(black)(m_("NaCl / 1 mole") = "58.44247 g")color(white)(a/a)|)))`