Question

Define the following terms:
(i) Mole fraction (ii) Isotonic solutions
(iii) Van't Hoff factor (iv) Ideal solution

Answer 1

I) Mole fraction is a unit of concentration, defined to be equal to the number of moles of a component divided by the total number of moles of a solution. Because it is a ratio, mole fraction is a unit less expression. The mole fraction of all components of a solution, when added together, will equal 1.

II) An isotonic solution refers to two solutions having the same osmotic pressure across a semipermeable membrane. This state allows for the free movement of water across the membrane without changing the concentration of solutes on either side.

III) The van 't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved, and the concentration of a substance as calculated from its mass.

IV) The concept of an ideal solution is fundamental to chemical thermodynamics and its applications, such as the use of colligative properties. An ideal solution or ideal mixture is a solution in which the enthalpy of solution ($\Delta H_{solution}$=0, $\Delta H_{solution}=0$ ) is zero; with the closer to zero the enthalpy of solution, the more "ideal" the behavior of the solution becomes. Since, the enthalpy of mixing (solution) is zero, the change in Gibbs energy on mixing is determined solely by the entropy of mixing ( $\Delta S_{solution}$ ).