posted by Max .
You need to find the number of moles in 5mL of a substance given the density and the molecular weight.
How do you do this?
lets take oxygen to be the substance given. the molecular weight also called the molar mass given as 16. the density always remain constant as 1g/ml. so lets comvert everything together as
5ml*1g/ml*1mole/16g = 0.313moles.
remember that 16g/mol is the molarmass or molecular weight.
The infor by chinomso is good except that the molar mass oxygen is 32 and not 16. Let's use something besides oxygen (especially since it doesn't have a density of 1.0 g/mL.)
H2O can be used and it does have a density of 1.0 g/mL.
So 5 mL x (1.0 g/mL) x (1 mol/18 g) = moles H2O where 18 is the molar mass of H2O.