Worksheet titled "Mass Mole Conversion Worksheet" with seven problems asking students to calculate the number of moles in given masses of different chemicals.

Let’s solve each problem step by step. We’re converting grams to moles, which means we need to use the formula:

> Moles = Mass (g) ÷ Molar Mass (g/mol)

We’ll find the molar mass of each compound using atomic masses from the periodic table (rounded to 2 decimal places for simplicity):

- C = 12.01 g/mol
- O = 16.00 g/mol
- Fe = 55.85 g/mol
- H = 1.01 g/mol
- Cl = 35.45 g/mol
- Na = 22.99 g/mol
- Ca = 40.08 g/mol

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① CO₂ → 28 grams

Molar mass of CO₂ = 12.01 + (2 × 16.00) = 12.01 + 32.00 = 44.01 g/mol

Moles = 28 ÷ 44.01 ≈ 0.636 mol

✔ Check: 44.01 × 0.636 ≈ 28 — good.

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② Fe₂O₃ → 79.85 grams

Molar mass of Fe₂O₃ = (2 × 55.85) + (3 × 16.00) = 111.70 + 48.00 = 159.70 g/mol

Moles = 79.85 ÷ 159.70 = 0.500 mol

✔ Check: 159.70 × 0.5 = 79.85 — perfect.

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③ H₂CO₃ → 8.045 grams

Molar mass of H₂CO₃ = (2 × 1.01) + 12.01 + (3 × 16.00) = 2.02 + 12.01 + 48.00 = 62.03 g/mol

Moles = 8.045 ÷ 62.03 ≈ 0.1297 mol

✔ Check: 62.03 × 0.1297 ≈ 8.045 — yes.

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④ H₂O → 27.2 grams

Molar mass of H₂O = (2 × 1.01) + 16.00 = 2.02 + 16.00 = 18.02 g/mol

Moles = 27.2 ÷ 18.02 ≈ 1.509 mol

✔ Check: 18.02 × 1.509 ≈ 27.2 — correct.

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⑤ HCl → 72.9 grams

Molar mass of HCl = 1.01 + 35.45 = 36.46 g/mol

Moles = 72.9 ÷ 36.46 ≈ 2.000 mol

✔ Check: 36.46 × 2 = 72.92 — very close (rounding error is tiny).

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⑥ NaOH → 140 grams

Molar mass of NaOH = 22.99 + 16.00 + 1.01 = 40.00 g/mol

Moles = 140 ÷ 40.00 = 3.50 mol

✔ Check: 40 × 3.5 = 140 — exact.

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⑦ CaCO₃ → 45.7 grams

Molar mass of CaCO₃ = 40.08 + 12.01 + (3 × 16.00) = 40.08 + 12.01 + 48.00 = 100.09 g/mol

Moles = 45.7 ÷ 100.09 ≈ 0.4566 mol

✔ Check: 100.09 × 0.4566 ≈ 45.7 — good.

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Final Answer:
① 0.636 mol
② 0.500 mol
③ 0.1297 mol
④ 1.509 mol
⑤ 2.000 mol
⑥ 3.50 mol
⑦ 0.4566 mol