Username:
   
Password:

I forgot my username or password.

In support of all the students who are displaced from school due to the Corona virus. Access to physics zone and chemistry zone lessons are now available free of charge. This will be maintained at least through August 1st 2020. Learn and be well.

Chemistry Lessons Review Links

Molecular Formula from Epirical Formula and Mass

Problem: A compound has an empirical formula of ClCH2 and a molecular weight of 98.96 g/mol. What is its molecular formula?

Strategy:

  1. Find the mass of the empirical unit.
    Mass of empirical unit = mass Cl + mass C + 2(mass H)

    Mass of empirical unit = 35.45 + 12.00 + 2(1.008) = 49.47 g/mol
     
  2. Figure out how many empirical units are in a molecular unit.
     
    # of empirical units = (mass of molecular unit/ mass of empirical unit)
    (98.96 g/mol) / (49.47 g/mol) = 2.000 empirical units per molecular unit
     
  3. Write the molecular formula.

Go back Go Next Step