A dilute solution of potassium permanganate in water at 25 °C was prepared. The solution was a in a horizontal tube of length 10 cm, as well as at first there was a linear gradation of intensity of the purple solution from the left where the concentration was 0.100 mol dm-3 to the right where the concentration was 0.050 mol dm-3. Explain what are the magnitude and sign of the thermodynamic force acting on the solute (a) close to the left face of the container, (b) in the middle, (c) close to the right face? Provide the force per mole as well as force per molecule in each case.