A mixture of FeO and Fe_(3)O_(4) was heated in air to a constant mass. It was found to gian 10% in its mass. Calculate the percentage composition of the origincal mixture.

A mixture of FeO and Fe_(3)O_(4) was heated in air to a constant mass.

1.	A mixture of FeO and Fe_(3)O_(4) was heated in air to a constant mass. It was found to gian 10% in its mass. Calculate the percentage composition of the origincal mixture.
Answer» Solution :On heating in air, both FeO and `Fe_(3)O_(4)` are oxidized to `Fe_(2)O_(3)` as follows : `underset(=144g)underset(2(56+16))(2FE)+(1)/(2)O_(2) rarrunderset(=160g)underset(2xx56+3xx16)(Fe_(2)O_(3)),""underset(=464 g)underset(2(3xx56+4xx16))(2Fe_(3)O_(4))+(1)/(2)O_(2) rarr underset(=480g)underset(3xx160)(3Fe_(2)O_(3))` Suppose `FeO` in the mixture `=X%` Then `Fe_(3)O_(4)` in the mixture `=(100-x)%` `Fe_(2)O_(3)` produced from x g of `FeO=(160)/(144)xx xg` Total `Fe_(2)O_(3)` produced from 100 g of the mixtuer `=100+10=110g` `therefore""(160x)/(144)+(480(100-x))/(464)=110` `"or"(10x)/(9)+(30(100-x))/(29)=110` `"or290x+270(100-x)=110xx9xx29 or 20x=1710 or x=85.5` `therefore FeO` present in the mixture `=85.5% and Fe_(3)O_(4)=100-85.5=12.4%`.