Consider the reaction below: S2O3^2-(aq) + 4 Cl2(g) + 5 H2O(l) → 2 SO4^2-(aq) + 8 Cl^-(aq) + 10 H+(aq) What is the oxidation number of S in S2O3^2-? Select | What is the oxidation number of S in SO4^2-? Select | In the reaction, Cl2 is Select |
The Correct Answer and Explanation is:
Let’s break down each part of the question:
- Oxidation number of sulfur in S2O3^2- (thiosulfate ion): The thiosulfate ion, S2O3^2-, contains two sulfur atoms. We can determine the oxidation number of sulfur by assigning oxidation numbers to the other atoms. Oxygen typically has an oxidation number of -2. There are three oxygen atoms in S2O3^2-, so the total oxidation number from oxygen is 3×(−2)=−63 \times (-2) = -63×(−2)=−6. The overall charge on the ion is -2, so the total oxidation number for the two sulfur atoms must balance out the -6 from oxygen and the -2 charge. Let the oxidation number of sulfur in S2O3^2- be xxx. For the two sulfur atoms, the total oxidation number is 2x2x2x. The equation becomes: 2x+(−6)=−22x + (-6) = -22x+(−6)=−2 Solving for xxx: 2x=4⇒x=+22x = 4 \quad \Rightarrow \quad x = +22x=4⇒x=+2 Therefore, the oxidation number of sulfur in S2O3^2- is +2.
- Oxidation number of sulfur in SO4^2- (sulfate ion): In the sulfate ion (SO4^2-), oxygen again has an oxidation number of -2. With four oxygen atoms, the total oxidation number from oxygen is 4×(−2)=−84 \times (-2) = -84×(−2)=−8. The overall charge on the ion is -2, so the oxidation number of sulfur must balance out the -8 from oxygen and the -2 charge. Let the oxidation number of sulfur in SO4^2- be xxx. The equation becomes: x+(−8)=−2x + (-8) = -2x+(−8)=−2 Solving for xxx: x=+6x = +6x=+6 Therefore, the oxidation number of sulfur in SO4^2- is +6.
- In the reaction, Cl2 is: To determine the role of Cl2 in the reaction, we need to consider its oxidation states before and after the reaction. On the left side, Cl2 is in its elemental form, which means each chlorine atom has an oxidation number of 0. On the right side, chlorine exists as Cl^-, which has an oxidation number of -1. The chlorine atoms are reduced from an oxidation state of 0 to -1, meaning Cl2 is reduced.
Summary of Answers:
- The oxidation number of sulfur in S2O3^2- is +2.
- The oxidation number of sulfur in SO4^2- is +6.
- In the reaction, Cl2 is reduced.
