Chemical Formula Writing Worksheet Solutions with answers for writing chemical formulas of compounds.

The image you've uploaded is a Chemical Formula Writing Worksheet Solutions document, which includes:

1. A grid showing chemical formulas formed by combining various cations (positive ions) with anions (negative ions).
2. A list of 12 compounds, with their correct chemical formulas provided as answers.

You're asking me to solve the problem and explain the solution. Since this is already a solution sheet, I’ll go through it step-by-step to explain how each formula was determined, especially focusing on the reasoning behind writing the correct chemical formulas based on charges and naming conventions.

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🔍 Understanding How Formulas Are Determined

To write correct chemical formulas, we follow these rules:

- Balance the charges of cations and anions so that the overall compound is neutral.
- Use subscripts to indicate how many of each ion are needed.
- For transition metals with variable charges (like Fe, Cr, Cu), the Roman numeral indicates the charge of the metal ion.
- Polyatomic ions (e.g., nitrate NO₃⁻, sulfate SO₄²⁻) must be treated as single units and enclosed in parentheses if more than one is used.

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## ✔ Part 1: Grid Explanation

This grid shows combinations of cations (Zn²⁺, Fe²⁺, Fe³⁺, Ga³⁺, Ag⁺, Pb⁴⁺) with common anions (Cl⁻, C₂H₃O₂⁻, NO₃⁻, O²⁻, N³⁻, SO₄²⁻).

Let’s take a few examples from the grid to illustrate:

| Cation | Anion | Charge | Formula |
|--------|-------|--------|---------|
| Zn²⁺ | Cl⁻ | +2 and -1 → need 2 Cl⁻ | ZnCl₂ |
| Fe²⁺ | O²⁻ | +2 and -2 → 1:1 ratio | FeO |
| Fe³⁺ | NO₃⁻ | +3 and -1 → need 3 NO₃⁻ | Fe(NO₃)₃ |
| Pb⁴⁺ | SO₄²⁻ | +4 and -2 → need 2 SO₄²⁻ | Pb(SO₄)₂ |

> Note: When more than one polyatomic ion is needed, use parentheses: e.g., Fe(NO₃)₃, not FeNO₃₃.

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## ✔ Part 2: Write Formulas for Given Compounds

Now let's go through each of the 12 listed compounds and explain how the formula is derived.

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1) Copper(II) chloride

- Copper(II) means Cu²⁺
- Chloride is Cl⁻
- To balance: 2 Cl⁻ needed for 1 Cu²⁺
- Formula: CuCl₂

✔

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2) Lithium acetate

- Lithium is Li⁺
- Acetate is C₂H₃O₂⁻
- 1:1 ratio
- Formula: LiC₂H₃O₂

✔

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3) Vanadium(II) selenide

- Vanadium(II) = V²⁺
- Selenide = Se²⁻
- Charges cancel in 1:1 ratio
- Formula: VSe

Wait! The answer given is V₂Se₃ — that’s incorrect.

✘ Error detected!

Let’s double-check:
- V²⁺ and Se²⁻ → should be VSe
- But V₂Se₃ would imply V has a +3 charge? Let’s see:
- 2×V = ? , 3×Se²⁻ = -6 → total negative = -6 → so V must be +3 → V³⁺

But the name says vanadium(II) → V²⁺

So V₂Se₃ cannot be correct.

✔ Correct formula should be: VSe

But the worksheet says V₂Se₃ — this is wrong.

> ⚠️ Correction: Vanadium(II) selenide is VSe, not V₂Se₃.

However, vanadium(III) selenide would be V₂Se₃.

So either the name or the formula is wrong. Based on naming, VSe is correct.

➡️ Likely error in the worksheet.

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4) Manganese(IV) nitride

- Mn⁴⁺
- Nitride = N³⁻
- Find LCM of 4 and 3 → 12
- 3 Mn⁴⁺ = +12
- 4 N³⁻ = -12
- So: Mn₃N₄

✔ Correct.

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5) Beryllium oxide

- Be²⁺
- O²⁻
- 1:1 ratio → BeO

✔ Correct.

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6) Sodium sulfate

- Na⁺
- SO₄²⁻
- Need 2 Na⁺ for 1 SO₄²⁻ → Na₂SO₄

✔ Correct.

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7) Aluminum arsenide

- Al³⁺
- As³⁻
- 1:1 ratio → AlAs

✔ Correct.

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8) Potassium permanganate

- K⁺
- Permanganate = MnO₄⁻
- 1:1 → KMnO₄

✔ Correct.

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9) Chromium(VI) cyanide

- Cr⁶⁺
- Cyanide = CN⁻
- Need 6 CN⁻ to balance → Cr(CN)₆

✔ Correct. Parentheses used because multiple polyatomic ions.

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10) Tin(II) sulfite

- Sn²⁺
- Sulfite = SO₃²⁻
- Charges match → SnSO₃

✔ Correct.

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11) Vanadium(V) fluoride

- V⁵⁺
- F⁻
- Need 5 F⁻ → VF₅

✔ Correct.

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12) Ammonium nitrate

- Ammonium = NH₄⁺
- Nitrate = NO₃⁻
- 1:1 → NH₄NO₃

✔ Correct.

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## ✘ Summary of Error Found

The only incorrect entry in the worksheet is:

> 3) vanadium(II) selenide → V₂Se₃

This is incorrect.

🔧 Correct Answer:

- Vanadium(II) = V²⁺
- Selenide = Se²⁻
- Charge balance: 1:1 → VSe

✔ Corrected Formula: VSe

If the formula were V₂Se₃, then the charge would be:
- 2×V = +6 → V³⁺ → vanadium(III) selenide

So the name should be vanadium(III) selenide.

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## ✔ Final Answers (with Corrections)

| No. | Compound | Correct Formula | Explanation |
|-----|------------------------|---------------------|-----------|
| 1 | Copper(II) chloride | CuCl₂ | Cu²⁺ + 2Cl⁻ |
| 2 | Lithium acetate | LiC₂H₃O₂ | Li⁺ + C₂H₃O₂⁻ |
| 3 | Vanadium(II) selenide | VSe | ✘ V₂Se₃ is wrong; should be VSe |
| 4 | Manganese(IV) nitride | Mn₃N₄ | Mn⁴⁺ and N³⁻ → 3:4 ratio |
| 5 | Beryllium oxide | BeO | Be²⁺ + O²⁻ |
| 6 | Sodium sulfate | Na₂SO₄ | 2Na⁺ + SO₄²⁻ |
| 7 | Aluminum arsenide | AlAs | Al³⁺ + As³⁻ |
| 8 | Potassium permanganate | KMnO₄ | K⁺ + MnO₄⁻ |
| 9 | Chromium(VI) cyanide | Cr(CN)₆ | Cr⁶⁺ + 6CN⁻ |
| 10 | Tin(II) sulfite | SnSO₃ | Sn²⁺ + SO₃²⁻ |
| 11 | Vanadium(V) fluoride | VF₅ | V⁵⁺ + 5F⁻ |
| 12 | Ammonium nitrate | NH₄NO₃ | NH₄⁺ + NO₃⁻ |

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## 📝 Conclusion

- Most formulas in the worksheet are correct.
- Only #3 is incorrect: "vanadium(II) selenide" should be VSe, not V₂Se₃.
- This highlights the importance of checking charge balance and Roman numerals when naming compounds.

Let me know if you'd like a printable version or a corrected worksheet!