Question

How many moles is 118 grams of Argon

Answer 1

Answer:

$\boxed {\boxed {\sf About \ 2.96 \ moles \ of \ Argon}}$

Explanation:

To convert from grams to moles we must use the molar mass, which is found on the Periodic Table.

• Argon: 39.9 g/mol

Use the molar mass as a ratio.

$\frac{39.9 \ g \ Ar}{1 \ mol \ Ar}$

Multiply by the given number of grams: 118

$118 \ g \ Ar *\frac{39.9 \ g \ Ar}{1 \ mol \ Ar}$

Flip the fraction so the grams of argon will cancel each other out.

$118 \ g\ Ar * \frac{1 \ mol \ Ar}{39.9 \ g \ Ar}$

$118 * \frac{ 1 \ mol \ Ar}{39.9 \ g \ Ar}$

$\frac {118 \ mol \ Ar }{ 39.9 }$

$2.95739348 \ mol \ Ar$

The original measurement of grams had 3 significant figures, so our answer must have 3 sig figs.

For the number we calculated, that is the hundredth place. The 7 in the thousandth place tells us to round the 5 to a 6.

$2.96 \ mol \ Ar$

There are about 2.96 moles of Argon in 118 grams.