H3AsO3 + NO3- + H+ ---> HNO2 + H3AsO4
In the above redox reaction, use oxidation numbers to identify the element oxidized, the element reduced, the oxidizing agent and the reducing agent.
Here are the rules for assigning oxidation states.
https://www.chemteam.info/Redox/Redox-Rules.html
Here is how you do it following those rules. Study this and you will be able to do it yourself.
H3AsO4. O is -2 each for a total of -8. H is +1 each for a total of +3. That leaves As. Since every eompound is zero, you know As must be +5 BECAUSE +3 +5 -8 = 0
The element oxidized is the one that lost electrons.
The element reduced is the one that gained electrons.
The oxidizing agent is the one that is reduced.
The reducing agent is the one that is oxidized.
I'll be happy to check your work. Look at N for the other element that changes oxidation state.
To determine the element that is oxidized and reduced, we first assign oxidation numbers to each element in the reaction:
H3AsO3 + NO3- + H+ ---> HNO2 + H3AsO4
Let's start by assigning oxidation numbers:
Let's assume that the oxidation number of hydrogen (H) is +1 and oxygen (O) is -2.
In H3AsO3, oxidation number of H is +1, and of O is -2, leaving arsenic (As) with an oxidation number of +3.
In NO3-, the oxidation number of oxygen is -2, and since there are three oxygen atoms, the total oxidation number contributed by oxygen is -6. Thus, the oxidation number of nitrogen (N) must be +5 to balance it out.
In H+, the oxidation number of hydrogen is +1.
In HNO2, the oxidation number of H is +1. Since oxygen is more electronegative than nitrogen, the oxidation state of oxygen is -2. Therefore, the oxidation number of nitrogen (N) is +3.
In H3AsO4, the oxidation number of H is +1, of O is -2, leaving arsenic (As) with an oxidation number of +5.
Now that we have assigned the oxidation numbers, we can identify the element oxidized and reduced, as well as the oxidizing and reducing agents.
The element oxidized is arsenic (As), which undergoes an increase in oxidation number from +3 in H3AsO3 to +5 in H3AsO4.
The element reduced is nitrogen (N), which undergoes a decrease in oxidation number from +5 in NO3- to +3 in HNO2.
The oxidizing agent is NO3-, as it causes the oxidation of arsenic by accepting electrons.
The reducing agent is H3AsO3, as it causes the reduction of nitrogen by donating electrons.
To identify the element that is oxidized and reduced, as well as the oxidizing agent and reducing agent in the given redox reaction, we need to determine the changes in oxidation numbers.
Step 1: Assign oxidation numbers to each element in the reactants and products.
- In H3AsO3 (arsenous acid), oxygen typically has an oxidation number of -2. Since there are three oxygen atoms, the total oxidation number contributed by oxygen is -6.
- The oxidation number of hydrogen (H) is usually +1.
- The overall charge of H3AsO3 is 0, which means the sum of the oxidation numbers should equal 0. Since there is no information given about the oxidation states of arsenic (As) and therefore they are not known, we denote it as "x."
- In NO3- (nitrate ion), the oxidation number of oxygen is typically -2, and since there are three oxygen atoms, the total oxidation number contributed by oxygen is -6. The oxidation number of nitrogen (N) can be calculated as:
O + (-2) = -1
-6 + (-2) = -1
-8 = -1
N = +5
- In H+ (hydrogen ion), the oxidation number of hydrogen is always +1.
- In HNO2 (nitrous acid), the oxidation number of hydrogen is +1. The oxidation number of nitrogen (N) is usually -3, and the overall charge is 0. Therefore, the oxidation number of oxygen can be calculated as:
H + (-3) + (-2) = 0
1 + (-3) + (-2) = 0
-4 = 0
O = +2
- In H3AsO4 (arsenic acid), the same assumptions follow as with H3AsO3. The oxidation number of oxygen is typically -2, and since there are four oxygen atoms, the total oxidation number contributed by oxygen is -8.
Step 2: Analyze the changes in oxidation numbers.
- The oxidation number of arsenic (As) in H3AsO3 is initially unknown (denoted as "x"), and it becomes +5 in H3AsO4. Therefore, the oxidation number of arsenic increases from x to +5, indicating that it is oxidized.
- The oxidation number of nitrogen (N) in NO3- is +5, and it becomes +3 in HNO2. Therefore, the oxidation number of nitrogen decreases from +5 to +3, indicating that it is reduced.
Step 3: Determine the oxidizing and reducing agents.
- The oxidizing agent is the species that gets reduced, while the reducing agent is the species that gets oxidized.
- In this reaction, NO3- is the oxidizing agent since it causes the reduction of nitrogen (N) from +5 to +3.
- H3AsO3 is the reducing agent since it causes the oxidation of arsenic (As) from an unknown oxidation state to +5.
Summary:
In the given redox reaction:
- The element oxidized is arsenic (As), which increases its oxidation number from an unknown value to +5.
- The element reduced is nitrogen (N), which decreases its oxidation number from +5 to +3.
- The oxidizing agent is NO3-, as it causes the reduction of nitrogen.
- The reducing agent is H3AsO3, as it causes the oxidation of arsenic.
Note: It is important to understand the concept of oxidation states and how to assign them to elements in compounds to identify the elements being oxidized or reduced, as well as the oxidizing and reducing agents.