# Which has more atoms: 17.031 grams of ammonia, NH_3, or 72.922 grams of hydrogen chloride, HCl?

Mar 11, 2017

$72.922 g$ of $H C l$

#### Explanation:

the answer to this would be the substance that has more moles.

$n = \frac{m}{M}$

(number of moles = mass/molar mass)

molar mass (g/mol) = atomic mass (g/mol), which can be found on the Periodic Table on the top-left of each element symbol.

${A}_{r} \left(N\right) = 14$
${A}_{r} \left(H\right) = 1$
${A}_{r} \left(C l\right) = 35.5$

${M}_{r} \left(N {H}_{3}\right) = \left(14 \cdot 1\right) + \left(1 \cdot 3\right)$
$= 14 + 3$
$= 17$

${M}_{r} \left(H C l\right) = 1 + 35.5$
$= 36.5$

$N {H}_{3}$:

$n = \frac{m}{M}$

$= \frac{17.031}{17}$

$\approx 1$ mole

$H C l$:

$n = \frac{m}{M}$

$= \frac{72.922}{36.5}$

$\approx 2$ moles

$1$ mole of atoms= $6.02 \cdot {10}^{23}$ atoms

$\therefore 2$ moles of atoms = $1$ mole of atoms $+ 6.02 \cdot {10}^{23}$ atoms

hence, there are more atoms in $72.922 g$ of $H C l$.