Question

What is the molar mass of lactic acid, `C_3H_6O_3`?

Answer 1

90.08 g/mol

Explanation:

Before we begin here's a tip:

atomic weight of element `xx`number of atoms given by subscript `=` molar mass

First, you want to have your handy dandy periodic table available so you can determine the atomic weight of C, H, O

C has an atomic weight of 12.01 g/mol
H has an atomic weight of 1.008 g/mol
O has an atomic wight of 16.00 g/mol

Based on the chemical formula, we have 3 atoms of carbon so you would multiply the atomic weight of C by 3 to obtain 36.03 g/mol.

You do the same for hydrogen, we have 6 atoms of H so you multiply the atomic weight of H by 6 to get 6.048 g/mol

Lastly, for O you would multiply 16.00g/mol by 3 to obtain 48.00 g/mol

Now you want to add the mass of each atom together to obtain the molecular weight of the entire compound:

48.00 g/mol + 6.048 g/mol + 36.03 g/mol = 90.08 g/mol