To find the molecular formula of a compound with a given empirical formula and molar mass, you can use the following steps:
Determine the molar mass of the empirical formula. The molar mass of a compound is the mass of one mole of the compound, and it is calculated by adding together the atomic weights of all the atoms in the compound. To determine the molar mass of the empirical formula C2OH4, you can add up the atomic weights of carbon (12.01 g/mol), hydrogen (1.01 g/mol), and oxygen (16.00 g/mol): 2 * 12.01 + 4 * 1.01 + 16.00 = 44.03 g/mol.
Divide the molar mass of the compound by the molar mass of the empirical formula. In this case, you can divide the molar mass of the compound (88 g/mol) by the molar mass of the empirical formula (44.03 g/mol): 88 / 44.03 = 1.999. This number is the multiple of the empirical formula that you need to multiply by to get the molecular formula.
Multiply the empirical formula by the multiple determined in step 2 to get the molecular formula. In this case, you can multiply the empirical formula C2OH4 by the multiple 1.999 to get the molecular formula C3.998OH7.996. However, since you cannot have fractional atoms, you need to round this formula to the nearest whole number. Rounding to the nearest whole number gives you C4OH8 as the molecular formula.
Therefore, the molecular formula of the compound with an empirical formula of C2OH4 and a molar mass of 88 g/mol is C4OH8.
It is important to note that the empirical formula only gives you the relative proportions of the atoms in a compound, not the actual number of atoms. The molecular formula, on the other hand, gives you the actual number of atoms of each element in the compound.