Question #306cf

1 Answer
Jul 20, 2017

Left side:

"K"K: 1+1+

"Cl"Cl: 7+7+

"O"O: 2-2

Right side:

"K"K: 1+1+

"Cl"Cl: 1-1

"O"O: 00

Explanation:

We're asked to assign an oxidation state to each element on both sides of the equation.

All pure elements have an oxidation state of 00, so the oxygen on the right side has an oxidation state of 00.

An important fact worth knowing is that oxygen will almost always have an oxidation state of 2-2 when in a compound. (The most common exception to this are superoxides, such as "KO"_2KO2).

Thus, oxygen on the left side has an oxidation state of 2-2.

Group 11 metals such as "Na"Na and "K"K will almost always have a 1+1+ oxidation state, so the potassium on both sides has an oxidation state of 1+1+.

Now, we only have "Cl"Cl left.

All neutral compounds have a net oxidation state of 00, so we use a little simple math to find the oxidation state of chlorine on both sides:

Left side:

"KClO"_4KClO4: overbrace(1+)^"K" + overbrace(x)^"Cl" + overbrace(4(2-))^(4color(white)(l)"O atoms") = 0

x = color(red)(+7

The oxidation state of "Cl" on the left side is thus color(red)(7+.

Right side:

"KCl": overbrace(1+)^"K" + overbrace(x)^"Cl" = 0

x = color(blue)(-1

The oxidation state of "Cl" on the right side is thus color(blue)(1-.