# What is the mass of 3 moles of "C"_2"H"_2 ?

Feb 26, 2018

$\text{78 g}$

#### Explanation:

Every mole of ${\text{C"_2"H}}_{2}$ (acetylene) has a mass of $\text{26.04 g}$, i.e. acetylene has a molar mass of $\text{26.04 g/mol}$.

Thus,

$\text{26.04 g/mol " * " 3 mol}$

gives you the mass of $3$ moles, $\text{78 g}$

Feb 26, 2018

Molar mass of ${C}_{2} {H}_{2} \implies 26 g$, that's the mass of 1 mole.

Therefore, mass of 3 moles of ${C}_{2} {H}_{2}$ would be 26 xx 3 = color(red)(78g

Feb 27, 2018

$78 \setminus \text{g}$

#### Explanation:

Acetylene $\left({C}_{2} {H}_{2}\right)$ has a molar mass of $26.04 \setminus \text{g/mol}$.

To find out the mass of moles, we have to multiply the number of moles by the molar mass of the substance, i.e. we can form an equation like this:

$\text{mass"="moles"*"molar mass}$

So, the mass of three moles of acetylene is

$\text{mass"_(C_2H_2)=3color(red)cancelcolor(black)"mol"*(26.04 \ "g")/(color(red)cancelcolor(black)"mol")=78.12 \ "g}$

Now, we can round off to the nearest whole number to make the answer more reasonable, so it'll be

$78.12 \setminus \text{g"~~78 \ "g}$