To calculate the mass of FeSO₄ needed to make a 10% by mass solution, we first need to know the total mass of the solution. In this case, the problem states that we have 200g of water. Therefore, the total mass of the solution will be 200g.

Next, we need to calculate what 10% of the total mass is. To do this, we multiply the total mass by the decimal equivalent of 10%.

10% = 0.10

0.10 x 200g = 20g

Therefore, we need 20g of FeSO₄ in our solution.



FeSO₄.7H₂O is a hydrated form of FeSO₄, meaning that it contains water molecules within its crystal structure. To calculate the mass of FeSO₄.7H₂O needed to make our solution, we need to take into account the mass of the water molecules as well.

The molar mass of FeSO₄ is 151.91 g/mol, and the molar mass of 7H₂O is 126.10 g/mol. Therefore, the molar mass of FeSO₄.7H₂O is:

(151.91 g/mol) + (7 x 18.02 g/mol) = 278.02 g/mol

To calculate the mass of FeSO₄.7H₂O needed, we divide the mass of FeSO₄ by the molar mass of FeSO₄.7H₂O and multiply by the molar mass of FeSO₄.7H₂O.

(20g FeSO₄) / (278.02 g/mol FeSO₄.7H₂O) x (278.02 g/mol FeSO₄.7H₂O) = 20g FeSO₄.7H₂O

Therefore, we need 20g of FeSO₄.7H₂O to make our solution.



To calculate the volume of FeSO₄.7H₂O needed, we need to know the density of the compound.