I need help understanding oxidation I have a problem that states:
The proper assignment of oxidation numbers to the elements in the compound LiAsO3 would be:
I think the answer is +1 for Li, +3 for As and -2 for O.
I think I am confusing oxidation with ionic charge.
PLEASE HELP
Li is right as is O. As is not right. As is +5
Here is a good site that explains how to do oxidation numbers.
http://www.chemteam.info/Redox/Redox-Rules.html
You're on the right track, but let me clarify the concept of oxidation numbers for you.
Oxidation numbers are assigned to individual atoms in a compound to determine their relative electron distribution. They are different from ionic charges, although they can sometimes be the same when dealing with simple ions.
To assign oxidation numbers, we follow a set of rules:
1. Elements in their elemental state (such as Li or As) have an oxidation number of zero.
2. For monoatomic ions, the oxidation number is equal to the charge of the ion. For example, Li+ has an oxidation number of +1.
3. In compounds, some elements tend to have specific oxidation numbers:
- Hydrogen (H) usually has an oxidation number of +1 when bonded to non-metals and -1 when bonded to metals.
- Oxygen (O) usually has an oxidation number of -2, except in peroxides (such as H2O2) where it is -1.
- Fluorine (F) always has an oxidation number of -1 when it is in a compound.
4. The sum of the oxidation numbers in a compound must equal zero for neutral compounds or the overall charge for polyatomic ions.
Now, let's determine the oxidation numbers for LiAsO3.
Since Li is an alkali metal, it typically has an oxidation number of +1.
For oxygen, we assume the usual oxidation number of -2. We have three oxygen atoms in the compound, so their total oxidation number contribution is -2x3 = -6.
To find the oxidation number for As, we can set up the equation:
(+1) + x + (-6) = 0
Simplifying, we have:
x - 5 = 0
x = +5
Therefore, the proper assignment of oxidation numbers to the elements in LiAsO3 is +1 for Li, +5 for As, and -2 for O.
I hope this clears up any confusion. Let me know if you have any further questions!
Oxidation numbers are different from ionic charges, but they are related. Oxidation numbers represent the hypothetical charge that an atom would have if all bonds in the compound were purely ionic. They are assigned by a set of rules and allow us to keep track of the transfer of electrons during chemical reactions.
To assign oxidation numbers, you can follow these general rules:
1. For elements in their elemental form (such as Li), the oxidation number is always zero.
2. For monatomic ions (such as Li+), the oxidation number is equal to the charge of the ion.
3. For compounds, some elements have typical oxidation numbers. For example, oxygen (O) usually has an oxidation number of -2, unless it is in a peroxide (such as H2O2) where its oxidation number is -1.
4. Hydrogen (H) usually has an oxidation number of +1 when bonded to nonmetals and -1 when bonded to metals.
5. The sum of all oxidation numbers in a compound must equal the overall charge of the compound, if it is a charged species.
Now, let's assign oxidation numbers to the elements in the compound LiAsO3:
1. Lithium (Li) is a Group 1 element, so it typically has an oxidation number of +1.
2. Oxygen (O) usually has an oxidation number of -2, so in this compound, there are three oxygen atoms, resulting in a total oxidation number of -6 (-2 x 3 = -6).
3. Now we need to find the oxidation number of arsenic (As) to balance the total oxidation number. Let's assume it is x.
The compound LiAsO3 has no overall charge specified, so the sum of the oxidation numbers should be zero.
The equation to represent the sum of oxidation numbers is:
(+1) + x + (-6) = 0
Simplifying the equation, we have:
x - 5 = 0
Solving for x, we find:
x = +5
Therefore, the proper assignment of oxidation numbers in the compound LiAsO3 would be +1 for Li, +5 for As, and -2 for each O atom.
Remember, assigning oxidation numbers is not based on the actual charge but rather on a hypothetical ionic charge if the compound were purely ionic.