Question

What is the concentration (in M) of a 225ml potassium sulfate solution that contains 4.15g of potassium?

Answer 1

The concentration of solution in M or mol/L can be calculated using the following formula:

`C=(n)/(V)` .... (1)

Here, n is number of moles and V is volume of solution in L.

The molecular formula of potassium sulfate is
`K_(2)SO_(4)` 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:

`n=(m)/(M)`

Here, m is mass and M is molar mass

Putting the values,

`n=((4.15 g)/((39.1 g/mol)=0.1061 mol`

Thus, number of moles of
`K_(2)SO_(4)` will be
`0.1061* 0.5=0.053 mol`.

The volume of solution is 225 mL, converting this into L,

`1 mL=10^(-3)L`

Thus,

`225 mL=0.225 L`

Putting the values in equation (1),

`C=((0.053 mol)/(0.225 L)=0.236 M`

Therefore, concentration of potassium sulfate solution is 0.236 M.