Question

1. give the oxidation number for each element in the following:

a) \\(\text{cl}_2\\)
b) \\(\text{hno}_3\\)
c) \\(\text{kmno}_4\\)
d) \\(\text{no}_3^{-1}\\)
e) \\(\text{h}_2\text{so}_4\\)
f) \\(\text{nh}_4^{+1}\\)

Explanation:

Identify rules for oxidation states

We apply standard rules to assign oxidation numbers:

1. Free elements in their molecular state have an oxidation number of \(0\).
2. Hydrogen is typically \(+1\) when bonded to nonmetals.
3. Oxygen is typically \(-2\) in most compounds.
4. Group 1 alkali metals (like \(\text{K}\)) always have an oxidation number of \(+1\).
5. The sum of oxidation numbers in a neutral compound is \(0\), and in a polyatomic ion, it equals the ion's charge.

Determine oxidation numbers for a, b, and c

• For a) \(\text{Cl}_2\):

This is a pure elemental form.

$$\text{Cl} = 0$$

• For b) \(\text{HNO}_3\):

Hydrogen is \(+1\), oxygen is \(-2\).

$$(+1) + \text{N} + 3(-2) = 0 \implies \text{N} = +5$$

$$\text{H} = +1, \quad \text{N} = +5, \quad \text{O} = -2$$

• For c) \(\text{KMnO}_4\):

Potassium is \(+1\), oxygen is \(-2\).

$$(+1) + \text{Mn} + 4(-2) = 0 \implies \text{Mn} = +7$$

$$\text{K} = +1, \quad \text{Mn} = +7, \quad \text{O} = -2$$

Determine oxidation numbers for d, e, and f

• For d) \(\text{NO}_3^{-1}\):

Oxygen is \(-2\). The sum equals the charge \(-1\).

$$\text{N} + 3(-2) = -1 \implies \text{N} = +5$$

$$\text{N} = +5, \quad \text{O} = -2$$

• For e) \(\text{H}_2\text{SO}_4\):

Hydrogen is \(+1\), oxygen is \(-2\).

$$2(+1) + \text{S} + 4(-2) = 0 \implies \text{S} = +6$$

$$\text{H} = +1, \quad \text{S} = +6, \quad \text{O} = -2$$

• For f) \(\text{NH}_4^{+1}\):

Hydrogen is \(+1\). The sum equals the charge \(+1\).

$$\text{N} + 4(+1) = +1 \implies \text{N} = -3$$

$$\text{N} = -3, \quad \text{H} = +1$$

Answer:

Question 7

a) \(\text{Cl}_2\):

• \(\text{Cl} = 0\)

b) \(\text{HNO}_3\):

• \(\text{H} = +1\)
• \(\text{N} = +5\)
• \(\text{O} = -2\)

c) \(\text{KMnO}_4\):

• \(\text{K} = +1\)
• \(\text{Mn} = +7\)
• \(\text{O} = -2\)

d) \(\text{NO}_3^{-1}\):

• \(\text{N} = +5\)
• \(\text{O} = -2\)

e) \(\text{H}_2\text{SO}_4\):

• \(\text{H} = +1\)
• \(\text{S} = +6\)
• \(\text{O} = -2\)

f) \(\text{NH}_4^{+1}\):

• \(\text{N} = -3\)
• \(\text{H} = +1\)