Molar Mass Worksheet for calculating the molar masses of various chemical compounds.

Let's solve the Molar Mass Worksheet step by step. We'll calculate the molar mass of each compound using the atomic masses from the periodic table (rounded to two decimal places where necessary).

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Atomic Masses (g/mol):

- H = 1.01
- C = 12.01
- N = 14.01
- O = 16.00
- F = 19.00
- Na = 22.99
- Mg = 24.31
- Al = 26.98
- P = 30.97
- S = 32.07
- Cl = 35.45
- K = 39.10
- Ca = 40.08
- Fe = 55.85
- Cu = 63.55
- Zn = 65.38
- Br = 79.90
- I = 126.90
- Pb = 207.2
- U = 238.03
- Be = 9.01
- B = 10.81
- Ga = 69.72

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Now, let’s calculate each one:

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1) Cl₂

- Cl: 35.45 × 2 = 70.90 g/mol

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2) KOH

- K: 39.10
- O: 16.00
- H: 1.01
- Total = 39.10 + 16.00 + 1.01 = 56.11 g/mol

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3) BeCl₂

- Be: 9.01
- Cl: 35.45 × 2 = 70.90
- Total = 9.01 + 70.90 = 79.91 g/mol

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4) FeCl₃

- Fe: 55.85
- Cl: 35.45 × 3 = 106.35
- Total = 55.85 + 106.35 = 162.20 g/mol

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5) BF₃

- B: 10.81
- F: 19.00 × 3 = 57.00
- Total = 10.81 + 57.00 = 67.81 g/mol

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6) CCl₂F₂ (Freon-12)

- C: 12.01
- Cl: 35.45 × 2 = 70.90
- F: 19.00 × 2 = 38.00
- Total = 12.01 + 70.90 + 38.00 = 120.91 g/mol

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7) Mg(OH)₂

- Mg: 24.31
- O: 16.00 × 2 = 32.00
- H: 1.01 × 2 = 2.02
- Total = 24.31 + 32.00 + 2.02 = 58.33 g/mol

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8) UF₆

- U: 238.03
- F: 19.00 × 6 = 114.00
- Total = 238.03 + 114.00 = 352.03 g/mol

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9) SO₂

- S: 32.07
- O: 16.00 × 2 = 32.00
- Total = 32.07 + 32.00 = 64.07 g/mol

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10) H₃PO₄

- H: 1.01 × 3 = 3.03
- P: 30.97
- O: 16.00 × 4 = 64.00
- Total = 3.03 + 30.97 + 64.00 = 98.00 g/mol

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11) (NH₄)₂SO₄

- N: 14.01 × 2 = 28.02
- H: 1.01 × 8 = 8.08
- S: 32.07
- O: 16.00 × 4 = 64.00
- Total = 28.02 + 8.08 + 32.07 + 64.00 = 132.17 g/mol

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12) CH₃COOH (Acetic acid)

- C: 12.01 × 2 = 24.02
- H: 1.01 × 4 = 4.04
- O: 16.00 × 2 = 32.00
- Total = 24.02 + 4.04 + 32.00 = 60.06 g/mol

> Note: CH₃COOH has 2 C, 4 H, and 2 O atoms.

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13) Pb(NO₃)₂

- Pb: 207.2
- N: 14.01 × 2 = 28.02
- O: 16.00 × 6 = 96.00
- Total = 207.2 + 28.02 + 96.00 = 331.22 g/mol

> Note: NO₃⁻ is a polyatomic ion; there are 2 NO₃ groups → 2 N and 6 O.

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14) Ga₂(SO₃)₃

- Ga: 69.72 × 2 = 139.44
- S: 32.07 × 3 = 96.21
- O: 16.00 × 9 = 144.00
- Total = 139.44 + 96.21 + 144.00 = 379.65 g/mol

> SO₃ group has 1 S and 3 O → 3 SO₃ → 3 S and 9 O

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✔ Final Answers:

| Number | Compound | Molar Mass (g/mol) |
|--------|----------------|--------------------|
| 1 | Cl₂ | 70.90 |
| 2 | KOH | 56.11 |
| 3 | BeCl₂ | 79.91 |
| 4 | FeCl₃ | 162.20 |
| 5 | BF₃ | 67.81 |
| 6 | CCl₂F₂ | 120.91 |
| 7 | Mg(OH)₂ | 58.33 |
| 8 | UF₆ | 352.03 |
| 9 | SO₂ | 64.07 |
| 10 | H₃PO₄ | 98.00 |
| 11 | (NH₄)₂SO₄ | 132.17 |
| 12 | CH₃COOH | 60.06 |
| 13 | Pb(NO₃)₂ | 331.22 |
| 14 | Ga₂(SO₃)₃ | 379.65 |

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🔍 Explanation:

To find the molar mass, we:
1. Identify all elements in the compound.
2. Count how many atoms of each element are present (including subscripts and parentheses).
3. Multiply each atomic mass by the number of atoms.
4. Add them together.

For example, in (NH₄)₂SO₄:
- Two NH₄⁺ ions → 2 N and 8 H
- One SO₄²⁻ → 1 S and 4 O
- So total: 2N + 8H + 1S + 4O

This method applies to all compounds.

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