Calculate the molecular mass worksheet - Free Printable

Let’s calculate the molar mass for each chemical one by one.
Molar mass = sum of atomic masses of all atoms in the formula (use periodic table values, rounded to 2 decimal places unless specified).

We’ll use these approximate atomic masses:
- H = 1.01
- C = 12.01
- N = 14.01
- O = 16.00
- F = 19.00
- Na = not needed here
- Mg = 24.31
- Al = not needed
- Si = not needed
- P = 30.97
- S = 32.07
- Cl = 35.45
- K = 39.10
- Ca = not needed
- Fe = 55.85
- Cu = not needed
- Zn = not needed
- Br = not needed
- I = not needed
- Be = 9.01
- B = 10.81
- Ga = 69.72
- Pb = 207.20
- U = 238.03

Now let’s go step by step:

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1) Cl₂
= 2 × Cl = 2 × 35.45 = 70.90 g/mol

2) KOH
K + O + H = 39.10 + 16.00 + 1.01 = 56.11 g/mol

3) BeCl₂
Be + 2×Cl = 9.01 + 2×35.45 = 9.01 + 70.90 = 79.91 g/mol

4) FeCl₃
Fe + 3×Cl = 55.85 + 3×35.45 = 55.85 + 106.35 = 162.20 g/mol

5) BF₃
B + 3×F = 10.81 + 3×19.00 = 10.81 + 57.00 = 67.81 g/mol

6) CCl₂F₂
C + 2×Cl + 2×F = 12.01 + 2×35.45 + 2×19.00 = 12.01 + 70.90 + 38.00 = 120.91 g/mol

7) Mg(OH)₂
Mg + 2×(O + H) = 24.31 + 2×(16.00 + 1.01) = 24.31 + 2×17.01 = 24.31 + 34.02 = 58.33 g/mol

8) UF₆
U + 6×F = 238.03 + 6×19.00 = 238.03 + 114.00 = 352.03 g/mol

9) SO₂
S + 2×O = 32.07 + 2×16.00 = 32.07 + 32.00 = 64.07 g/mol

10) H₃PO₄
3×H + P + 4×O = 3×1.01 + 30.97 + 4×16.00 = 3.03 + 30.97 + 64.00 = 98.00 g/mol

11) (NH₄)₂SO₄
Break it down:
2×N + 8×H + S + 4×O
= 2×14.01 + 8×1.01 + 32.07 + 4×16.00
= 28.02 + 8.08 + 32.07 + 64.00
Add step by step:
28.02 + 8.08 = 36.10
36.10 + 32.07 = 68.17
68.17 + 64.00 = 132.17 g/mol

12) CH₃COOH → This is acetic acid. Formula can be written as C₂H₄O₂
2×C + 4×H + 2×O = 2×12.01 + 4×1.01 + 2×16.00 = 24.02 + 4.04 + 32.00 = 60.06 g/mol

13) Pb(NO₃)₂
Pb + 2×N + 6×O = 207.20 + 2×14.01 + 6×16.00 = 207.20 + 28.02 + 96.00 =
207.20 + 28.02 = 235.22
235.22 + 96.00 = 331.22 g/mol

14) Ga₂(SO₃)₃
Break it down:
2×Ga + 3×S + 9×O
= 2×69.72 + 3×32.07 + 9×16.00
= 139.44 + 96.21 + 144.00
Add step by step:
139.44 + 96.21 = 235.65
235.65 + 144.00 = 379.65 g/mol

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Final Answer:
1) 70.90 g/mol
2) 56.11 g/mol
3) 79.91 g/mol
4) 162.20 g/mol
5) 67.81 g/mol
6) 120.91 g/mol
7) 58.33 g/mol
8) 352.03 g/mol
9) 64.07 g/mol
10) 98.00 g/mol
11) 132.17 g/mol
12) 60.06 g/mol
13) 331.22 g/mol
14) 379.65 g/mol