I need to identify the elements oxidized and reduced and indicate which
substances are the oxidizing and reducing agents for the redox reaction:
PH3(g) + O2(g) → P2O5(s) + H2O(g)
P goes from+3 to +5: it lost electrons, and therefor is oxidized.
O2 goes from zero to -2, it gained electrons, and therefore is reduced.
P is the reducing agent, O is the oxidizing agent.
Awesome! Thanks:)
To identify the elements that are oxidized and reduced in a redox reaction, you need to determine the changes in oxidation states of the elements involved. Here's how you can do it for the given reaction:
1. Write out the balanced chemical equation:
PH3(g) + O2(g) → P2O5(s) + H2O(g)
2. Determine the oxidation state of each element in the reactants and products. The sum of the oxidation states of all the atoms in a compound must equal the charge of that compound.
a. In PH3, hydrogen (H) generally has an oxidation state of +1, so the total oxidation state for three hydrogens is +3. The charge on the phosphorus (P) atom is equal to the sum of all the oxidation states of the other atoms, so the oxidation state of P is -3.
b. In O2, oxygen generally has an oxidation state of -2. Since there are two oxygen atoms in O2, the total oxidation state for oxygen is -4.
c. In P2O5, the total oxidation state for oxygen is -10 (5 × -2). The sum of the oxidation states for the two phosphorus atoms must equal the charge on the compound, which is 0. Therefore, the oxidation state of each phosphorus atom is +5.
d. In H2O, hydrogen generally has an oxidation state of +1. The total oxidation state for two hydrogens is +2. The sum of the oxidation states for oxygen and hydrogen must equal the charge on the compound, which is 0. Therefore, the oxidation state of oxygen is -2.
3. Identify the element that undergoes an increase in its oxidation state. This element is oxidized. In the given reaction, the oxidation state of phosphorus increases from -3 in PH3 to +5 in P2O5. Therefore, phosphorus is oxidized.
4. Identify the element that undergoes a decrease in its oxidation state. This element is reduced. In the given reaction, the oxidation state of oxygen decreases from 0 in O2 to -2 in H2O. Therefore, oxygen is reduced.
5. The oxidizing agent is the element or compound that causes another element to be oxidized. In this reaction, oxygen is the oxidizing agent because it causes the oxidation of phosphorus.
6. The reducing agent is the element or compound that causes another element to be reduced. In this reaction, PH3 is the reducing agent because it causes the reduction of oxygen.
Therefore, in the redox reaction:
PH3(g) + O2(g) → P2O5(s) + H2O(g)
Phosphorus (P) is oxidized, oxygen (O) is reduced, oxygen is the oxidizing agent, and PH3 is the reducing agent.