Question

Assign oxidation state to elements whose atoms are underlined in each of the following compounds or ions:

1. KNO₃
2. AlH₃
3. NH₄⁺
4. H₂PO₄^-

Short answer

The respective oxidation states are:

1. N = +5
2. Al = +3
3. N = -3
4. P = +5

Step-by-step solution

Determine oxidation state of part (a)

Write the oxidation state of the elements.

K = +1 because it is an alkali metal.

O = +2

Let Nbe x as we need to find its value.

Plugging the values

+1 + x + (-2 x 3) = 0, as it is neutral compound.

x = +5

Therefore, N = +5.

Determine oxidation state of part (b)

Write the oxidation state of the elements.

H = -1

Let AI be x as we need to find its value.

Plugging the values

x + (-1 x 3) = 0, as it is neutral compound.

x = +3.

Therefore, Al = +3.

Determine oxidation state of part (c)

Write the oxidation state of the elements.

H = +1

Let N be x as we need to find its value.

Plugging the values

x + 1 x 4 = +1, as the total value will be equal to the charge given on the compound.

x = -3.

Therefore, N= -3.

Determine oxidation state of part (d)

Write the oxidation state of the elements.

H = +1

O = -2

Let P be xas we need to find its value.

Plugging the values

2 x 1 + x + (-2 x 4) = -1, as the total oxidation state equals to the charge given on the compound.

x = +5

Therefore, P= +5.