Final answer:
To determine the molecular formula of a compound with an empirical formula of CH and a molar mass of 78.12 g/mol, divide the molar mass of the compound by the molar mass of the empirical formula, and multiply the empirical formula by this number to get the molecular formula, which is C6H6.
Step-by-step explanation:
A student asked what the molecular formula of a compound is if its empirical formula is CH and its molar mass is 78.12 g/mol. To find the molecular formula, we first calculate the molar mass of the empirical formula. In this case, the empirical formula CH has a molar mass of approximately 13.02 g/mol (carbon is about 12.01 g/mol and hydrogen about 1.01 g/mol). Next, you divide the molar mass of the compound by the molar mass of the empirical formula: 78.12 g/mol ÷ 13.02 g/mol = 6. So, the molecular formula contains six times more atoms than the empirical formula, which means that the molecular formula is C6H6.