text: how do you calculate molar mass of liquid? i would like to know what i need to know and how to calculate this value. i would like a formula that would be nice or any other help. there are many ways to go about this problem.  what do you know about the liquid?  if you don't know the molecular formula, then experimentally you need to determine the moles of the liquid and the mass of the liquid.  the mass is easy, you can either weigh the liquid, or you can measure it's volume and if you know the density, you can calculate the mass.  weighing is the more accurate method.  calculating the moles of a liquid.  there are many different types of experiments to do that... but the experiment that you do depends on the type of compound you have.  sorry, but this question is a little vague and i'd need to know specifics to help you any more.