determine the oxidation number of
MgBR2(s)
and
NH4No3(s)
You want the numbers for the molecule to add to zero. For example, Mg is in group II so it is +2. Br is -1(group VIIA or 17 depending upon the system you are using), there are two of them for a total if -2. +2 and -2 = 0
Here are a set of simple rules for helping determine the oxidation state of elements in compounds. Read those and do NH4NO3.
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To determine the oxidation numbers of the elements in a compound, you need to consider the electronegativity and the known rules or guidelines for assigning oxidation numbers.
Let's start with MgBr2(s):
MgBr2 is composed of magnesium (Mg) and bromine (Br).
1. Magnesium (Mg) typically has an oxidation number of +2. This is because magnesium readily loses two electrons to form stable cations.
2. Bromine (Br) is part of Group 17 (or Group VIIA) in the periodic table, which means it has a common oxidation number of -1. However, in this compound, it is combined with another bromine atom. Therefore, the total charge must add up to zero to maintain neutrality.
Since there are two bromine atoms in MgBr2, each with an oxidation number of -1, the total charge is -2. Since the overall charge of the compound must be zero, the oxidation number of magnesium (Mg) can be calculated as +2 to balance the bromine's -2.
Therefore, the oxidation number of magnesium (Mg) in MgBr2(s) is +2.
Now let's consider NH4NO3(s):
NH4NO3 is composed of ammonium ions (NH4+) and nitrate ions (NO3-).
1. The ammonium ion (NH4+) is a positively charged ion. Since there is only one nitrogen (N) atom in this compound, and the overall charge is +1, each hydrogen (H) atom must have an oxidation number of +1. Therefore, the oxidation number of nitrogen (N) in NH4+ is -3. To determine this, you need to know that the sum of the oxidation numbers in a compound equals the overall charge.
2. The nitrate ion (NO3-) is a negatively charged ion. The oxygen atoms (O) in NO3- generally have an oxidation number of -2. Since there are three oxygen atoms in the nitrate ion, they contribute -6 to the overall charge.
To calculate the oxidation number of nitrogen (N), subtract the total contribution of the oxygen atoms (-6) from its overall charge (-1). Therefore, the oxidation number of nitrogen (N) in NO3- is +5.
In NH4NO3, you have four ammonium ions (NH4+) with an overall charge of +4 (+1 × 4 = +4), and one nitrate ion (NO3-) with an overall charge of -1. To maintain charge neutrality, the oxidation number of nitrogen (N) should be such that the total charge adds up to zero.
To calculate the oxidation number of nitrogen (N), subtract the total charge of the ammonium ions (+4) from the overall charge of the nitrate ion (-1). Therefore, the oxidation number of nitrogen (N) in NH4NO3 is +3.
So, the oxidation number of nitrogen (N) in NH4NO3(s) is +3.
In summary:
- The oxidation number of magnesium (Mg) in MgBr2(s) is +2.
- The oxidation number of nitrogen (N) in NH4NO3(s) is +3.