Question #8b7ec

1 Answer
Apr 25, 2016

2.75 moles #xx# molar mass of carbon dioxide


(n) = number of moles,
(m) = mass of substance,
(M) = molar mass (equivalent to atomic weight on the periodic table)

#n = m -: M#

2.75 moles (n) has been provided for you

The next step is to find out the molar mass (M) of carbon dioxide before proceeding to find the mass of substance (m).

To be able to find the molar mass, you have to know what are the elements present in carbon dioxide.
Since the formula of carbon dioxide is #CO_2#, the elements present are carbon and oxygen.

The molar mass of carbon is 12.0 g/mol and oxygen is 16.0 g/mol.
Since there are two oxygens present, you have to times 16.0 by 2 and it becomes 32.0 g/mol.
The molar mass (M) of #CO_2# is [12.0 g/mol + 32.0 g/mol] = 44.0 g/mol.

Since you've found the molar mass (M) and number of moles (n), you can now find the mass (m).

Looking back at the #n = m -: M# formula, make the (m) become the unknown. #(m = M xx n) #

The mass of #CO_2# is [44.0 g/mol #xx#2.75 moles] = 121 grams.

Therefore, the mass of 2.75 moles of #CO_2# is 121 grams.