Let’s solve the problem step by step.
We are asked to calculate the
relative formula mass of several substances. Relative formula mass is just the sum of the relative atomic masses (RAM) of all the atoms in the formula. We use values from the periodic table — usually rounded to whole numbers for GCSE level:
- Calcium (Ca) = 40
- Sulfur (S) = 32
- Oxygen (O) = 16
- Magnesium (Mg) = 24
- Sodium (Na) = 23
- Carbon (C) = 12
- Butane is C₄H₁₀ → Hydrogen (H) = 1
---
1. Calcium Sulfate → CaSO₄
Atoms:
- 1 × Ca = 40
- 1 × S = 32
- 4 × O = 4 × 16 = 64
Total = 40 + 32 + 64 =
136
✔ Formula: CaSO₄
✔ Relative formula mass:
136
---
2. Magnesium Oxide → MgO
Atoms:
- 1 × Mg = 24
- 1 × O = 16
Total = 24 + 16 =
40
✔ Formula: MgO
✔ Relative formula mass:
40
---
3. Sodium Carbonate → Na₂CO₃
Atoms:
- 2 × Na = 2 × 23 = 46
- 1 × C = 12
- 3 × O = 3 × 16 = 48
Total = 46 + 12 + 48 =
106
✔ Formula: Na₂CO₃
✔ Relative formula mass:
106
---
4. Oxygen → O₂ (it’s a diatomic molecule!)
Atoms:
- 2 × O = 2 × 16 =
32
✔ Formula: O₂
✔ Relative formula mass:
32
---
5. Butane → C₄H₁₀
Atoms:
- 4 × C = 4 × 12 = 48
- 10 × H = 10 × 1 = 10
Total = 48 + 10 =
58
✔ Formula: C₄H₁₀
✔ Relative formula mass:
58
---
Now let’s fill in the table as requested:
| Substance | Chemical Formula | Relative Formula Mass |
|-------------------|------------------|------------------------|
| Calcium Sulfate | CaSO₄ | 136 |
| Magnesium Oxide | MgO | 40 |
| Sodium Carbonate | Na₂CO₃ | 106 |
| Oxygen | O₂ | 32 |
| Butane | C₄H₁₀ | 58 |
All calculations checked and verified.
Final Answer:
Calcium Sulfate: CaSO₄, 136
Magnesium Oxide: MgO, 40
Sodium Carbonate: Na₂CO₃, 106
Oxygen: O₂, 32
Butane: C₄H₁₀, 58
Parent Tip: Review the logic above to help your child master the concept of formula mass worksheet.
