a beaker contains 500ml of 12m potassium nitrate. what is the molarity of the new solution if 250 ml more water is added

8.0 M.

Explanation:

It is known that the no. of millimoles after dilution is equal to the no. of millimoles before dilution.

∴ (MV) of KNO₃ before dilution = (MV) of KNO₃ before dilution.

Before dilution:

M = 12.0 M, V = 500.0 mL.

After dilution:

M = ? M, V = 500.0 mL + 250.0 mL = 750.0 mL.

∴ M after dilution = (MV) before dilution / (V) after dilution = (12.0 M) (500.0 mL) / (750.0 mL) = 8.0 M.