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

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Answer 1 · 2017-03-11T15:18:59

$72.922g$ of $HCl$

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

$n = m/M$

(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.

$A_r (N) = 14$
$A_r (H) = 1$
$A_r (Cl) = 35.5$

$M_r(NH_3) = (14 * 1) + (1 * 3)$
$= 14+3$
$= 17$

$M_r(HCl) = 1 + 35.5$
$= 36.5$

$NH_3$ :

$n = m/M$

$=17.031/17$

$~~1$ mole

$HCl$ :

$n = m/M$

$=72.922/36.5$

$~~2$ moles

$1$ mole of atoms= $6.02 * 10^23$ atoms
(Avogadro's constant)

$therefore 2$ moles of atoms = $1$ mole of atoms $+6.02 * 10^23$ atoms

hence, there are more atoms in $72.922g$ of $HCl$ .

Which has more atoms: 17.031 grams of ammonia, NH_3NH_3, or 72.922 grams of hydrogen chloride, HClHCl?