The concentration of solution in M or mol/L can be calculated using the following formula:
[tex]C=\frac{n}{V}[/tex] .... (1)
Here, n is number of moles and V is volume of solution in L.
The molecular formula of potassium sulfate is [tex]K_{2}SO_{4}[/tex] thus, there are 2 moles of potassium in 1 mol of potassium sulfate.
1 mol of potassium will be there in 0.5 mol of potassium sulfate.
Mass of potassium is 4.15 g, molar mass is 39.1 g/mol.
Number of moles can be calculated as follows:
[tex]n=\frac{m}{M}[/tex]
Here, m is mass and M is molar mass
Putting the values,
[tex]n=\frac{(4.15 g}{(39.1 g/mol}=0.1061 mol[/tex]
Thus, number of moles of [tex]K_{2}SO_{4}[/tex] will be [tex]0.1061\times 0.5=0.053 mol[/tex].
The volume of solution is 225 mL, converting this into L,
[tex]1 mL=10^{-3}L[/tex]
Thus,
[tex]225 mL=0.225 L[/tex]
Putting the values in equation (1),
[tex]C=\frac{(0.053 mol}{0.225 L}=0.236 M[/tex]
Therefore, concentration of potassium sulfate solution is 0.236 M.