Benzene has the empirical formula and an empirical formula weight of 13.0 amu. If the molecular weight is 78.0 amu, what is the molecular formula? (Enter the elements in the order: C, H.)

Molecular formula for benzene is C₆H₆

Explanation:

Benzene has this empirical formula → CH

Empirical weight = 13 amu

12 amu from C + 1 amu from H = 13 amu

To determine the molecular formula we can think this equation:

12 amu X, from C + 1 amu X from H = 78 amu

13 amu X = 78 amu

X = 78 amu / 13 amu = 6 → Molecular formula for benzene is C₆H₆

The empirical formula indicates what proportion of atoms there is for a given compound. Sometimes it can match the molecular formula of the compound

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6