Question

A compound has an empirical formula of `HCO_2` and a molecular mass of 90 grams per mole. What is the molecular formula of this compound?

Answer 1

The molecular formula is always a multiple of the empirical formula: `("empirical formula")_n ="molecular formula"`.

Explanation:

So `(1.00794 + 12.011 + 2xx15.999)*g*mol^-1xxn` `=` `90*g*mol^-1`.

We solve for `n`, and clearly `n` `=` `2`.

So empirical formula is `C_2H_2O_4`.