Predicting the products of electrolysis worksheet with a table and true/false questions.

Let's solve this step by step.

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Part 1: Predicting Products of Electrolysis

In electrolysis:
- Negative electrode (cathode): Reduction occurs. Cations (positive ions) are attracted here and gain electrons.
- Positive electrode (anode): Oxidation occurs. Anions (negative ions) are attracted here and lose electrons.

Rules to determine products:

#### At the cathode (negative electrode):
- If the metal is above hydrogen in the reactivity series, hydrogen gas is produced.
- If the metal is below hydrogen, the metal itself is deposited.
- Exceptions: For very reactive metals like sodium, potassium, etc., hydrogen is still produced because they react violently with water.

#### At the anode (positive electrode):
- Halide ions (Cl⁻, Br⁻, I⁻): These are oxidized to form halogen gases (Cl₂, Br₂, I₂).
- Sulfate (SO₄²⁻) or nitrate (NO₃⁻): Water is oxidized to produce oxygen gas.
- Fluoride (F⁻): Very stable; water is oxidized instead → oxygen gas.
- Hydroxide (OH⁻): Also leads to oxygen gas when present (from water dissociation).

> Note: In aqueous solutions, water molecules can also be involved. So, we must consider both ions and water.

Let’s go through each compound:

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1. Copper chloride (CuCl₂)

- Ions: Cu²⁺, Cl⁻
- Cathode: Cu²⁺ is below H in reactivity → Copper metal deposited.
- Anode: Cl⁻ is halide → Chlorine gas (Cl₂) evolved.
✔ Answer:
- Negative: Copper
- Positive: Chlorine

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2. Silver bromide (AgBr)

- Ions: Ag⁺, Br⁻
- Cathode: Ag⁺ is below H → Silver metal deposited.
- Anode: Br⁻ → Bromine gas (Br₂).
✔
- Negative: Silver
- Positive: Bromine

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3. Magnesium chloride (MgCl₂)

- Ions: Mg²⁺, Cl⁻
- Cathode: Mg²⁺ is above H → Hydrogen gas (H₂) from water.
- Anode: Cl⁻ → Chlorine gas (Cl₂).
✔
- Negative: Hydrogen
- Positive: Chlorine

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4. Lead sulfate (PbSO₄)

- Ions: Pb²⁺, SO₄²⁻
- Cathode: Pb²⁺ is below H? Actually, lead is just below H but not very reactive — Lead metal may deposit, but it's borderline. However, since Pb²⁺ is less reactive than H, it can be deposited.
- But in aqueous solution, Pb²⁺ is reduced to Pb metal at cathode.
- Anode: SO₄²⁻ → Oxygen gas (O₂) (water oxidized).
✔
- Negative: Lead
- Positive: Oxygen

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5. Silver nitrate (AgNO₃)

- Ions: Ag⁺, NO₃⁻
- Cathode: Ag⁺ → Silver metal.
- Anode: NO₃⁻ → Oxygen gas (water oxidized).
✔
- Negative: Silver
- Positive: Oxygen

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6. Iron chloride (FeCl₂)

- Ions: Fe²⁺, Cl⁻
- Cathode: Fe²⁺ is above H → Hydrogen gas (H₂) from water.
- Anode: Cl⁻ → Chlorine gas (Cl₂).
✔
- Negative: Hydrogen
- Positive: Chlorine

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7. Zinc fluoride (ZnF₂)

- Ions: Zn²⁺, F⁻
- Cathode: Zn²⁺ is above H → Hydrogen gas (H₂).
- Anode: F⁻ is very stable → Water oxidized → Oxygen gas (O₂).
✔
- Negative: Hydrogen
- Positive: Oxygen

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8. Potassium sulfate (K₂SO₄)

- Ions: K⁺, SO₄²⁻
- Cathode: K⁺ is very reactive → Hydrogen gas (H₂) from water.
- Anode: SO₄²⁻ → Oxygen gas (O₂).
✔
- Negative: Hydrogen
- Positive: Oxygen

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9. Sodium iodide (NaI)

- Ions: Na⁺, I⁻
- Cathode: Na⁺ is very reactive → Hydrogen gas (H₂).
- Anode: I⁻ → Iodine (I₂) gas or solid.
✔
- Negative: Hydrogen
- Positive: Iodine

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10. Silver chloride (AgCl)

- Ions: Ag⁺, Cl⁻
- Cathode: Ag⁺ → Silver metal.
- Anode: Cl⁻ → Chlorine gas (Cl₂).
✔
- Negative: Silver
- Positive: Chlorine

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11. Copper sulfate (CuSO₄)

- Ions: Cu²⁺, SO₄²⁻
- Cathode: Cu²⁺ below H → Copper metal.
- Anode: SO₄²⁻ → Oxygen gas (O₂).
✔
- Negative: Copper
- Positive: Oxygen

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12. Calcium fluoride (CaF₂)

- Ions: Ca²⁺, F⁻
- Cathode: Ca²⁺ is above H → Hydrogen gas (H₂).
- Anode: F⁻ is stable → Oxygen gas (O₂) from water.
✔
- Negative: Hydrogen
- Positive: Oxygen

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✔ Final Table:

| Q | Ionic Solution | Negative Electrode | Positive Electrode |
|---|-----------------------|--------------------|---------------------|
| 1 | Copper chloride (CuCl₂) | Copper | Chlorine |
| 2 | Silver bromide (AgBr) | Silver | Bromine |
| 3 | Magnesium chloride (MgCl₂)| Hydrogen | Chlorine |
| 4 | Lead sulfate (PbSO₄) | Lead | Oxygen |
| 5 | Silver nitrate (AgNO₃) | Silver | Oxygen |
| 6 | Iron chloride (FeCl₂) | Hydrogen | Chlorine |
| 7 | Zinc fluoride (ZnF₂) | Hydrogen | Oxygen |
| 8 | Potassium sulfate (K₂SO₄)| Hydrogen | Oxygen |
| 9 | Sodium iodide (NaI) | Hydrogen | Iodine |
|10 | Silver chloride (AgCl) | Silver | Chlorine |
|11 | Copper sulfate (CuSO₄) | Copper | Oxygen |
|12 | Calcium fluoride (CaF₂) | Hydrogen | Oxygen |

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Part 2: True or False Questions

#### 13. Oxidation is the gain of electrons.
✘ False
→ Oxidation is loss of electrons.
Reduction is gain.

#### 14. Reduction happens at the negative electrode.
✔ True
→ Negative electrode = cathode = reduction.

#### 15. Ionic substances conduct electricity in any state (solid, liquid or gas).
✘ False
→ Only in molten or aqueous state. In solid state, ions are fixed and cannot move.

#### 16. At the negative electrode the metal will be produced if it is more reactive than hydrogen.
✘ False
→ If the metal is more reactive than hydrogen, hydrogen gas is produced instead (because the metal ion doesn’t get reduced easily).
So, only less reactive metals (below H) are deposited.

#### 17. If sulfate ions are present oxygen is produced at the positive electrode.
✔ True
→ Sulfate ions are not oxidized; instead, water is oxidized to produce oxygen gas at the anode.

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✔ Final Answers for True/False:

| Q | Statement | True | False |
|---|---------|------|-------|
|13| Oxidation is the gain of electrons. | | ✔ |
|14| Reduction happens at the negative electrode. | ✔ | |
|15| Ionic substances conduct electricity in any state... | | ✔ |
|16| At the negative electrode the metal will be produced if it is more reactive than hydrogen. | | ✔ |
|17| If sulfate ions are present oxygen is produced at the positive electrode. | ✔ | |

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✔ Summary

This completes the entire worksheet. The key concepts are:
- Use the reactivity series to predict which cation is reduced.
- Use ion stability and competition to determine anode products.
- Remember that water can interfere in aqueous solutions.

Let me know if you'd like a printable version or explanation in simpler terms!