Molar Mass Worksheet – Elements Molar Mass - Free Printable

Let's solve the Molar Mass Worksheet - Elements step by step.

We’ll use the formula:

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

We'll need the molar masses of the elements from the periodic table:

- Na (Sodium): 23.0 g/mol
- Ca (Calcium): 40.1 g/mol
- Mg (Magnesium): 24.3 g/mol
- Al (Aluminum): 27.0 g/mol
- H (Hydrogen): 1.0 g/mol
- Hg (Mercury): 200.6 g/mol
- Li (Lithium): 6.9 g/mol
- Ne (Neon): 20.2 g/mol
- Zn (Zinc): 65.4 g/mol
- Br (Bromine): 79.9 g/mol

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Problem 1: Calculate the mass in grams

| | Molar Mass (g/mol) | Mass (g) |
|---|---------------------|---------|
| a. 3.00 moles Na | 23.0 | 3.00 × 23.0 = 69.0 g |
| b. 2.50 moles Ca | 40.1 | 2.50 × 40.1 = 100.25 g |
| c. 5.00 moles Mg | 24.3 | 5.00 × 24.3 = 121.5 g |
| d. 4.00 mole Al | 27.0 | 4.00 × 27.0 = 108.0 g |
| e. 3.00 moles H | 1.0 | 3.00 × 1.0 = 3.0 g |
| f. 0.275 moles Hg | 200.6 | 0.275 × 200.6 = 55.175 g |

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Problem 2: Calculate the number of moles

| | Molar Mass (g/mol) | # of Moles |
|---|---------------------|------------|
| a. 25.0 grams Li | 6.9 | 25.0 ÷ 6.9 ≈ 3.62 mol |
| b. 60.0 grams Ne | 20.2 | 60.0 ÷ 20.2 ≈ 2.97 mol |
| c. 180.0 grams Ca | 40.1 | 180.0 ÷ 40.1 ≈ 4.49 mol |
| d. 150.0 grams Zn | 65.4 | 150.0 ÷ 65.4 ≈ 2.29 mol |
| e. 160.0 grams Br | 79.9 | 160.0 ÷ 79.9 ≈ 2.00 mol |
| f. 11.9 grams of Al | 27.0 | 11.9 ÷ 27.0 ≈ 0.441 mol |

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✔ Final Answers:

#### Problem 1 – Mass (g):
a. 69.0 g
b. 100.25 g
c. 121.5 g
d. 108.0 g
e. 3.0 g
f. 55.175 g

#### Problem 2 – Moles:
a. 3.62 mol
b. 2.97 mol
c. 4.49 mol
d. 2.29 mol
e. 2.00 mol
f. 0.441 mol

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🔍 Explanation:

- The molar mass is the mass of one mole of a substance (in g/mol), found on the periodic table.
- To find mass, multiply moles by molar mass.
- To find moles, divide mass by molar mass.
- Always round appropriately based on significant figures (usually to 3 sig figs unless specified).

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