Free Printable Molar Mass Worksheet Answers for Students - Free Printable

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 (since 4 H per NH₄, and 2 NH₄ groups)
- 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

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13) Pb(NO₃)₂

- Pb: 207.2
- N: 14.01 × 2 = 28.02
- O: 16.00 × 6 = 96.00 (3 O per NO₃, 2 NO₃ → 6 O)
- Total = 207.2 + 28.02 + 96.00 = 331.22 g/mol

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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 (3 O per SO₃, 3 SO₃ → 9 O)
- Total = 139.44 + 96.21 + 144.00 = 379.65 g/mol

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✔ Final Answers:

| 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 of a compound:
1. Identify all elements in the formula.
2. Count how many atoms of each element are present.
3. Multiply each atomic mass by the number of atoms.
4. Add all contributions together.

For polyatomic ions or parentheses like (NH₄)₂SO₄ or (SO₃)₃, remember to multiply the contents inside the parentheses by the subscript outside.

Let me know if you'd like this as a downloadable PDF or need help with any specific calculation!