what is the oxidation number of Mg(ClO4)2
The correct answer and explanation is :
To determine the oxidation number of magnesium in ( \text{Mg(ClO}_4)_2 ), we need to analyze the oxidation states of all elements involved in the compound.
Step 1: Assign oxidation numbers to known components
We know the following:
- The oxidation number of magnesium (Mg) in most of its compounds is +2. This is because magnesium is an alkaline earth metal (Group 2 of the periodic table), and it tends to lose two electrons to form a 2+ ion.
- The perchlorate ion (( \text{ClO}_4^- )) is a polyatomic ion. In this ion:
- Oxygen typically has an oxidation number of -2.
- The overall charge of the perchlorate ion is -1.
Let’s calculate the oxidation number of chlorine in ( \text{ClO}_4^- ).
Step 2: Calculate the oxidation number of chlorine in the perchlorate ion
For the perchlorate ion ( \text{ClO}_4^- ), the sum of the oxidation numbers of all atoms must equal the charge of the ion, which is -1. Let the oxidation number of chlorine in ( \text{ClO}_4^- ) be ( x ). Since oxygen is typically -2, the four oxygens contribute ( 4 \times (-2) = -8 ).
The total oxidation number for the ion is:
[
x + (-8) = -1
]
Solving for ( x ):
[
x – 8 = -1 \
x = +7
]
Thus, the oxidation number of chlorine in ( \text{ClO}_4^- ) is +7.
Step 3: Determine the oxidation number of magnesium
Now, we know the oxidation number of chlorine in ( \text{ClO}_4^- ) is +7, and the oxidation number of oxygen in ( \text{ClO}_4^- ) is -2. The compound ( \text{Mg(ClO}_4)_2 ) contains two ( \text{ClO}_4^- ) ions. The total charge from the two ( \text{ClO}_4^- ) ions is ( 2 \times (-1) = -2 ).
The overall charge of the compound is neutral, so the charge from magnesium must balance out the total charge of the two ( \text{ClO}_4^- ) ions. Since the two ( \text{ClO}_4^- ) ions contribute -2 charge, the magnesium ion must have a +2 charge to balance the equation.
Thus, the oxidation number of magnesium (Mg) in ( \text{Mg(ClO}_4)_2 ) is +2, as expected from its position in the periodic table and its typical chemical behavior.