Final answer:
To find the relative formula mass of aluminium sulfate, multiply the atomic masses of Al (27), S (32), and O (16) by the number of each atom in the formula and add the values together, resulting in a total of 342 amu.
Step-by-step explanation:
The student has asked how to calculate the relative formula mass of aluminium sulfate, Al2(SO4)3. This involves adding the atomic masses of all the atoms in the formula of the compound. Here is the calculation:
- Aluminium (Al) has a relative atomic mass (Ar) of 27 and there are two aluminium atoms in the compound.
- Sulfur (S) has an Ar of 32 and there are three sulfur atoms in the compound.
- Oxygen (O) has an Ar of 16 and there are twelve oxygen atoms in the compound.
By multiplying the atomic mass of each element by the number of atoms of that element in the compound and summing them all, the relative formula mass of aluminium sulfate can be found:
((2 × 27) + (3 × 32) + (12 × 16)) = 54 + 96 + 192 = 342 amu
Hence, the relative formula mass of aluminium sulfate, Al2(SO4)3, is 342 amu.