Calculate the relative formula mass (Mᵣ) of Fe₂O₃.\nRelative atomic masses (Aᵣ): O = 16, Fe = 56
How to approach this question
1. Identify the number of atoms of each element in the formula Fe₂O₃. There are 2 iron (Fe) atoms and 3 oxygen (O) atoms.\n2. Find the relative atomic mass (Aᵣ) for each element from the information given (Fe = 56, O = 16).\n3. Multiply the number of atoms of each element by its Aᵣ.\n4. Add the results together to get the total relative formula mass (Mᵣ).
Full Answer
The relative formula mass (Mᵣ) is the sum of the relative atomic masses (Aᵣ) of all the atoms in the formula.\nThe formula is Fe₂O₃.\nThis contains:\n- 2 atoms of Iron (Fe)\n- 3 atoms of Oxygen (O)\n\nUsing the given Aᵣ values:\nAᵣ of Fe = 56\nAᵣ of O = 16\n\nMᵣ of Fe₂O₃ = (2 × Aᵣ of Fe) + (3 × Aᵣ of O)\nMᵣ = (2 × 56) + (3 × 16)\nMᵣ = 112 + 48\nMᵣ = 160
Common mistakes
✗ Multiplying the number of atoms incorrectly (e.g., 2 × 16 and 3 × 56).\n✗ Adding the Aᵣ values without multiplying by the number of atoms (56 + 16).
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