I have problems with the oxidation numbers of
a) POCl3
b) HClO3
Please help!!
O is -2. Cl is -3 and there are thee of them for -3. Total is -5; therefore, P must be +5 for the compound to be zero. (All compounds are zero).
H is +1. O is 3x -2 for -6. Cl must be +5 for the compound to be zero.
Of course, I'd be happy to help you with the oxidation numbers of the elements in POCl3 and HClO3.
To determine the oxidation numbers, also known as oxidation states, there are some general guidelines to follow:
1. The oxidation number of an atom in its elemental form is always zero. For example, in a molecule of Cl2, each chlorine atom has an oxidation number of zero.
2. The sum of the oxidation numbers in a neutral compound is always zero. For example, in H2O, the oxidation number of hydrogen is +1 (rule 3 explains why) and oxygen is -2, which balances out to zero.
3. Hydrogen typically has an oxidation number of +1, unless it's combined with a metal in a binary compound, in which case it has an oxidation number of -1. Exceptions to this rule include metal hydrides where hydrogen acts as a hydride ion, such as LiH, where hydrogen has an oxidation number of -1.
4. Oxygen usually has an oxidation number of -2. However, there are exceptions such as in peroxides (e.g., H2O2) and when it's combined with more electronegative elements like fluorine, where it can have a positive oxidation number.
Now let's apply these guidelines to the compounds you mentioned:
a) POCl3:
To find the oxidation number of each element in POCl3, we can start by assigning an oxidation number to oxygen (-2) and hydrogen (+1) based on the general guidelines.
Let's assume that the oxidation number of phosphorus is x.
We know that the compound is neutral, so we can set up the following equation:
(-2) + x + (-2) + (-2) + (-2) = 0
Simplifying the equation, we have:
x - 8 = 0
x = 8
Therefore, the oxidation number of phosphorus in POCl3 is +5, which is also known as the oxidation state.
b) HClO3:
Following the same approach, let's assign an oxidation number to hydrogen and oxygen first.
Assuming that the oxidation number of chlorine is y, we can set up the equation as follows:
(+1) + y + (-2) + (-2) + (-2) = 0
Simplifying the equation, we have:
y - 5 = 0
y = 5
Therefore, the oxidation number of chlorine in HClO3 is +5.
To summarize:
a) The oxidation number of phosphorus in POCl3 is +5.
b) The oxidation number of chlorine in HClO3 is +5.
By applying the general guidelines, we can determine the oxidation numbers of elements in compounds.