Determine the empirical formula `(EF)` of the oxide of chomium containing `68.4% Cr` by mass.
A. `Cr O_(3)`
B. `Cr_(2) O_(3)`
C. `Cr O_(5)`
D. `Cr_(3) O_(4)`
A. `Cr O_(3)`
B. `Cr_(2) O_(3)`
C. `Cr O_(5)`
D. `Cr_(3) O_(4)`
Correct Answer – B
`n_(Cr) = (68.4g)/(52g mol^(-1)) = 1.32, n_(O) = (31.6g)/(16g mol^(-1)) = 1.98`
`(n_(Cr))/(n_(O)) = (1.32)/(1.98) = (132)/(198) = (2xx66)/(3xx66) = (2)/(3)`
`:. EF` is `Cr_(2) O_(3)`.