Question

/1/hydrocarbons

What is the formal oxidation state of carbon in CH4?

2/polyatomic anion

What is the oxidation state of oxygen in chlorate ([ClO₃]^-)?

3/polyatomic anion again

What is the oxidations tate of Br in bromate ([BrO₃]^-)?

Answer 1

1)

Oxidation number of H = +1

lets the oxidation number of C be x

use:

4* oxidation number (H) + 1* oxidation number (C) = net charge

4*(+1)+1* x = 0

4 + 1 * x = 0

x = -4

So oxidation number of C = -4

Answer: -1

2)

Oxidation number of O = -2

lets the oxidation number of Cl be x

use:

3* oxidation number (O) + 1* oxidation number (Cl) = net charge

3*(-2)+1* x = -1

-6 + 1 * x = -1

x = 5

So oxidation number of Cl = +5

Answer: +5

3)

Oxidation number of O = -2

lets the oxidation number of Br be x

use:

3* oxidation number (O) + 1* oxidation number (Br) = net charge

3*(-2)+1* x = -1

-6 + 1 * x = -1

x = 5

So oxidation number of Br = +5

Answer: +5