Question

How do I find the percentage composition of Chlorine in `CoCl_2`?

Answer 1

The percent composition of chlorine in `"CoCl"_2"` is `54.611%`.

Explanation:

First determine the molar mass of cobalt chloride `("CoCl"_2")` and the mass of chlorine in the compound. Divide the mass of chlorine by the molar mass of cobalt chloride, then multiply by 100.

Molar Mass of Cobalt Chloride

`"CoCl"_2":` `overbrace((1xx58.933195 "g/mol"))^color(blue)"cobalt"+overbrace((2xx35.453 "g/mol"))^color(red)"chlorine"=overbrace"129.839 g/mol"^color(purple)"cobalt chloride"`

Mass of Chlorine in Cobalt Chloride

`"Cl"_2":` `(2xx35.453 "g/mol")="70.906 g/mol"`

Percent Composition of Chlorine

`%"Composition of Cl"=(70.906 cancel"g/mol")/(129.839 cancel"g/mol")xx100="54.611%`