Final answer:
To determine the molecular formula of a compound with an empirical formula of CH and a molar mass of 78.11 g/mol, you must find the mass of the empirical formula, divide the molar mass by this value, and multiply the empirical formula by the resultant number. The molecular formula is found to be C6H6.
Step-by-step explanation:
Determining the Molecular Formula:
To find the molecular formula of a compound with an empirical formula of CH and a molar mass of 78.11 g/mol, we must first find the mass of the empirical formula. The molar mass of carbon (C) is approximately 12.01 g/mol and for hydrogen (H) it is about 1.008 g/mol. Therefore, the empirical formula mass of CH is 12.01 g/mol + 1.008 g/mol which equals 13.018 g/mol.
Next, we divide the molar mass of the compound by the empirical formula mass to find the multiple of the empirical formula needed to get the molecular formula: 78.11 g/mol ÷ 13.018 g/mol, which equals approximately 6. Therefore, the molecular formula of the compound is 6 times the empirical formula. Since the empirical formula is CH, multiplying this by 6 gives us C6H6, which is the molecular formula of the compound.
This process of determining the molecular formula from the empirical formula and molar mass is a key aspect of molecular characterization in Chemistry.