Question

The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are $x , y$ and $z$. The sum of $x , y$ and $z$ is______.

$\underset{(A)}{Na_4[Fe(CN)_5NOS)]} \,\,\, \underset{(B)}{Na_4[FeO_4]} \,\,\, \underset{(C)}{[Fe_2(CO)_9]}$

Answer 1

(A) $Na _{4}\left[ \overset{x}{Fe} ( CN )_{5}( NOS )\right]$

$(+1) 4+ x +(-1) 5+(-1) 1=0$

$x =+2$

(B) $Na _{4}\left[ \overset{y}{Fe} O _{4}\right]$

$(+1) 4+ y +(-2) 4=0$

y $=+4$

(C) $\left[ \overset{z}{Fe} _{2}( CO )_{9}\right]$

$2 z +0 \times 9=0$

$z =0$

so $( x + y + z )=+2+4+0$

$=6$