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What is the oxidation number (i) of oxygen in H₂O, and (ii) of bromine in KBrO? - Leaving Cert Chemistry - Question g - 2004
Question g
What is the oxidation number (i) of oxygen in H₂O, and (ii) of bromine in KBrO?
Worked Solution & Example Answer:What is the oxidation number (i) of oxygen in H₂O, and (ii) of bromine in KBrO? - Leaving Cert Chemistry - Question g - 2004
Step 1
(i) of oxygen in H₂O
Answer
In H₂O, the oxidation number of oxygen is typically -1. This is because hydrogen has an oxidation state of +1, and to maintain electroneutrality in H₂O, the oxygen must have an oxidation state of -2, since there two hydrogen atoms. Therefore, the calculation confirms that
o + 2(+1) = 0
o = -2.
Step 2
(ii) of bromine in KBrO
Answer
In KBrO, potassium (K) has an oxidation number of +1, and oxygen generally has an oxidation number of -2. Let’s denote the oxidation state of bromine (Br) as x. The sum of all oxidation states should equal 0, resulting in the equation:
x + 1 + (-2) = 0.
Solving for x, we find that:
x - 1 = 0 ightarrow x = +1.
However, the oxidation state of bromine here is +5 as it is in the +5 oxidation state in this compound, considering the overall oxidation numbers balance.