Question

A mixture contains 20% iron ions by mass. What mass of iron chloride (FeCl) would

you need to provide the iron ions in 50 g of the mixture? A of Fe = 56, A of Cl = 35.5.
.

Answer 1

Mass of iron chloride (FeCl₂) : 22.68 g

Further explanation

Proust stated the Comparative Law that compounds are formed from elements with the same Mass Comparison so that the compound has a fixed composition of elements

In the same compound, although from different sources and formed by different processes, it will still have the same composition/comparison

With this law, we can calculate how many grams an element is needed to make a compound with a certain mass, as desired

`\tt mass~Fe=(Ar~Fe)/(MW~FeCl_2)* mass~FeCl_2`

The iron ions in 50 g mixture :

`\tt 20\%* 50~g=10~g`

`\tt 10=(56)/(127)* mass~FeCl_2\\\\mass~FeCl_2=22.68~g`