To determine the elements undergoing oxidation and reduction in the reaction \( \text{CrO}_5 + \text{SnCl}_2 \rightarrow \text{CrO}_4^{2-} + \text{SnCl}_4 \), we need to analyze the oxidation states of the elements involved.
### Step-by-Step Solution:
1. **Identify the oxidation states of chromium (Cr) and tin (Sn):**
- In \( \text{CrO}_5 \), chromium (Cr) has an oxidation state of +6. This is because oxygen (O) typically has an oxidation state of -2, and there are 5 oxygen atoms contributing a total of -10. To balance this, Cr must be +6.
- In \( \text{CrO}_4^{2-} \), chromium (Cr) still has an oxidation state of +6. The overall charge of -2 from the \( \text{CrO}_4^{2-} \) means that Cr must still be +6 to balance the -8 from the four oxygen atoms (-2 each).
2. **Identify the oxidation states of tin (Sn):**
- In \( \text{SnCl}_2 \), tin (Sn) has an oxidation state of +2. Each chlorine (Cl) has an oxidation state of -1, and with two Cl atoms, this totals -2, balancing Sn's +2.
- In \( \text{SnCl}_4 \), tin (Sn) has an oxidation state of +4. With four Cl atoms at -1 each, the total is -4, balancing Sn's +4.
3. **Determine changes in oxidation states:**
- **For chromium (Cr):** The oxidation state remains +6 in both reactants and products, indicating no change.
- **For tin (Sn):** The oxidation state changes from +2 in \( \text{SnCl}_2 \) to +4 in \( \text{SnCl}_4 \). This is an increase in oxidation state, indicating that tin is oxidized.
- **For oxygen (O):** In \( \text{CrO}_5 \), the oxidation state of oxygen is -1 (as part of a peroxide), and in \( \text{CrO}_4^{2-} \), the oxidation state of oxygen is -2. This is a decrease in oxidation state, indicating that oxygen is reduced.
4. **Conclusion:**
- The element undergoing oxidation is tin (Sn), and the element undergoing reduction is oxygen (O).
### Final Answer:
- The element undergoing oxidation is **tin (Sn)** and the element undergoing reduction is **oxygen (O)**.
