# The mineral greenockite is a yellow sulfide of cadmium that is 78.0% cadmium and 22.0% sulfur. How do you determine the empirical formula of greenockite?

##### 1 Answer

#### Answer:

The empirical formula is

#### Explanation:

Start by assuming a mass of

i.e. there are

Convert each mass to moles:

#"Cd: " "78 g" / "112.4 g/mol" = "0.694 mol"#

#"S: " "22 g" / "32.06 g/mol" = "0.686 mol"#

To two digits, these values are equal, so the whole number ratio of mol (and therefore atoms) in the compound is

The empirical formula is

Note, if it is not obvious how to get a whole number ratio as above, the best way to proceed is to divide each number of moles by the smallest value. This should make it easier to get the ratio.