Molar Mass Practice Worksheet featuring ten chemical compounds for calculating molar masses.

Let's solve each of these molar mass problems step by step. The molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). We calculate it by summing the atomic masses of all atoms in the compound using the periodic table.

We'll use standard atomic masses (rounded to two decimal places):

- H = 1.01 g/mol
- C = 12.01 g/mol
- N = 14.01 g/mol
- O = 16.00 g/mol
- F = 19.00 g/mol
- Na = 22.99 g/mol
- Mg = 24.31 g/mol
- Al = 26.98 g/mol
- P = 30.97 g/mol
- S = 32.07 g/mol
- Cl = 35.45 g/mol
- K = 39.10 g/mol
- Ca = 40.08 g/mol
- Fe = 55.85 g/mol
- Cu = 63.55 g/mol
- Zn = 65.38 g/mol
- Br = 79.90 g/mol
- Ag = 107.87 g/mol
- Pb = 207.2 g/mol

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1) NaBr

- Na: 22.99 g/mol
- Br: 79.90 g/mol
- Molar mass = 22.99 + 79.90 = 102.89 g/mol

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2) PbSO₄

- Pb: 207.2 g/mol
- S: 32.07 g/mol
- O₄: 4 × 16.00 = 64.00 g/mol
- Molar mass = 207.2 + 32.07 + 64.00 = 303.27 g/mol

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3) Ca(OH)₂

- Ca: 40.08 g/mol
- O: 2 × 16.00 = 32.00 g/mol
- H: 2 × 1.01 = 2.02 g/mol
- Molar mass = 40.08 + 32.00 + 2.02 = 74.10 g/mol

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4) Na₃PO₄

- Na₃: 3 × 22.99 = 68.97 g/mol
- P: 30.97 g/mol
- O₄: 4 × 16.00 = 64.00 g/mol
- Molar mass = 68.97 + 30.97 + 64.00 = 163.94 g/mol

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5) (NH₄)₂CO₃

- N₂: 2 × 14.01 = 28.02 g/mol
- H₈: 8 × 1.01 = 8.08 g/mol
- C: 12.01 g/mol
- O₃: 3 × 16.00 = 48.00 g/mol
- Molar mass = 28.02 + 8.08 + 12.01 + 48.00 = 96.11 g/mol

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6) C₆H₁₂O₆

- C₆: 6 × 12.01 = 72.06 g/mol
- H₁₂: 12 × 1.01 = 12.12 g/mol
- O₆: 6 × 16.00 = 96.00 g/mol
- Molar mass = 72.06 + 12.12 + 96.00 = 180.18 g/mol

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7) Fe₃(PO₄)₂

- Fe₃: 3 × 55.85 = 167.55 g/mol
- P₂: 2 × 30.97 = 61.94 g/mol
- O₈: 8 × 16.00 = 128.00 g/mol
- Molar mass = 167.55 + 61.94 + 128.00 = 357.49 g/mol

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8) (NH₄)₂S

- N₂: 2 × 14.01 = 28.02 g/mol
- H₈: 8 × 1.01 = 8.08 g/mol
- S: 32.07 g/mol
- Molar mass = 28.02 + 8.08 + 32.07 = 68.17 g/mol

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9) Zn(C₂H₃O₂)₂

This is zinc acetate. The acetate ion is C₂H₃O₂⁻, so two of them:
- Zn: 65.38 g/mol
- C₄: 4 × 12.01 = 48.04 g/mol
- H₆: 6 × 1.01 = 6.06 g/mol
- O₄: 4 × 16.00 = 64.00 g/mol
- Molar mass = 65.38 + 48.04 + 6.06 + 64.00 = 183.48 g/mol

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10) AgF

- Ag: 107.87 g/mol
- F: 19.00 g/mol
- Molar mass = 107.87 + 19.00 = 126.87 g/mol

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✔ Final Answers:

1) NaBr – 102.89 g/mol
2) PbSO₄ – 303.27 g/mol
3) Ca(OH)₂ – 74.10 g/mol
4) Na₃PO₄ – 163.94 g/mol
5) (NH₄)₂CO₃ – 96.11 g/mol
6) C₆H₁₂O₆ – 180.18 g/mol
7) Fe₃(PO₄)₂ – 357.49 g/mol
8) (NH₄)₂S – 68.17 g/mol
9) Zn(C₂H₃O₂)₂ – 183.48 g/mol
10) AgF – 126.87 g/mol

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