# Question c894f

Oct 13, 2015

Here's what you need to do.

#### Explanation:

To get the formula mass of sodium chloride, $\text{NaCl}$, you need to add the molar masses of its constituent atoms, sodium and chlorine.

The atomic masses of sodium and of chlorine are

$\text{Na: " "22.990 u}$

$\text{Cl: " "35.453 u}$

Since a formula unit of sodium chloride cotnains *one* sodium atom and one** chlorine atom, the formula mass of sodium chloride will be

$1 \times \text{22.990 u" + 1 xx "35.453 u" = "58.443 u}$

To get the percent composition of the compound, use the atomic masses of each constituent atom and the formula mass

$\text{For Na: " (22.990color(red)(cancel(color(black)("u"))))/(58.443color(red)(cancel(color(black)("u")))) xx 100 = "39.34% Na}$

$\text{For Cl: "(35.453color(red)(cancel(color(black)("u"))))/(58.443color(red)(cancel(color(black)("u")))) xx 100 = "60.66% Cl}$

So, according to the percent composition of sodium chloride, every $\text{100 g}$ of sodium chloride will contain "39.34% sodium and 60.66%# chlorine.