Question

What are the oxidation numbers of K, C, and O in K2CO3?

Answer 1

The oxidation number of potassium in compounds is always +1 and that of oxygen is almost always -2. Call the oxidation number of carbon in potassium carbonate n. Then, since the sum of the products of all the oxidation numbers of the elements in a compound multiplied by the number of atoms of that element must be 0, n + 2(1) + 3(-2) must be zero, or n must be +4.

Answer 2

K = +1

O = -2

C = +4

Step-by-step explanation:

1. Find the oxidation number for K:

As the potassium is a metal from the group I in the periodic table, it has the number of oxidation +1

`K^(+1)_(2)CO_(3)`

2. Find the oxidation number for O:

As the number of valence electrons of the oxygen is 6, its oxidation number is -2, that is the number of electrons left to complete the octet rule.

`K^(+1)_(2)CO^(-2)_(3)`

3. Find the oxidation number for C:

To find this oxidation number first multiply the oxidation numbers of the other elements by the quantity of each element in the molecular formula.

K = +1 * 2 = +2

O = -2 * 3 = -6

Therefore the oxidation number for C will be +4 because the addition of the oxidation numbers in the molecule must be equal to zero.

`K^(+1)_(2)C^(+4) O^(-2)_(3)`