<u>Answer:</u> The theoretical yield of iron(III) sulfate is 26.6 grams
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
.....(1)
Given mass of iron(III) phosphate = 20.00 g
Molar mass of iron(III) phosphate = 150.82 g/mol
Putting values in equation 1, we get:

The given chemical equation follows:

As, sodium sulfate is present in excess. So, it is considered as an excess reagent.
Thus, iron(III) phosphate is considered as a limiting reagent because it limits the formation of product.
By Stoichiometry of the reaction:
2 moles of iron(III) phosphate produces 1 mole of iron(III) sulfate
So, 0.133 moles of iron(III) phosphate will produce =
of iron(III) sulfate
Now, calculating the mass of iron(III) sulfate from equation 1, we get:
Molar mass of iron(III) sulfate = 399.9 g/mol
Moles of iron(III) sulfate = 0.0665 moles
Putting values in equation 1, we get:

Hence, the theoretical yield of iron(III) sulfate is 26.6 grams