How many moles are there in 4.56 g of lactic acid?

Question

I have 90.08 g/mol for molar mass, where do I go from there?

Answer 1

If you have 90.08 g/mol and 4.56g and you want to get mol
Lets try a few things:
1) 90.08g/mol * 4.56g = 410.8g^2/mol <-- not the right units we want!
2) 90.08g/mol / 4.56g = 19.75 1/mol <-- the right unit but inversed! (you can choose to inverse this answer to get the correct answer and stop here)
3) 4.56g / 90.08g/mol = 0.05062 mol <-- success!

A bit of a long explanation, but I hope this helps with unit manipulation now and for later on in your education!

Answer 2

Divide the Gram of lactic acid in the molar mass
4.56g *(1mol/90.08)

Answer 3

simple you divide your mass by the molecular weight so


4.56/90.08 =0.0506 mole

Answer 4

use dimensional analysis, multply 4.56 g to (1 mole/90.08 gram) then you can already get the moles