Sammy R. answered 11/04/20
HS Chemistry Teacher with 8 years of Experience
hi there, I will need a little bit more info about your question to 100% help but here are some basics I can give you based on the info provided...lets start with molar mass.
to calculate to the molar mass, you find the atomic mass on the periodic table, multiply it by the number of that particular element then add up all the atoms in the compound. for example: H2O-H has an atomic mass of 1.008 amu x 2 (bc there are 2 atoms of Hydrogen) = 2.016amu then O has an atomic mass of 15.999amu and there's only one of them so you just add that together with H. 2.016+15.999=18.015g
in order to convert from grams to moles, you will need to the given amount of grams and divide that by the molar mass. for example: lets say you had 2.0g of water to convert that to moles you will divide 2.0g by the molar mass we calculated earlier (18.015g). 2.0g/18.015g=0.111mol H2O
hope this helps, if you want to comment and add more info about your question I can try to help further.