Chemistry solutions

• The solute can be any type of particle (solid, liquid or gas).
• The concentration of a solution refers to the amount of solute present per unit volume of solution.
• Different types of solutions include gas, liquid, and solid solutions.
• Concentration of a solution can be expressed in various units.
• Henry’s law and Raoult’s law are two important laws related to solutions.
• Ideal and non-ideal solutions are different types of solutions.
• Real solutions deviate from Raoult’s law.
• Colligative properties of solutions can be correlated with molar masses of the solutes.
• Some solutes exhibit abnormal colligative properties in solutions.
• As dissolution is an exothermic process, the solubility should decrease with increase of temperature.
• When dissolved, the gas molecules are present in liquid phase and the process of dissolution can be considered similar to condensation and heat is evolved in this process.
• When taken in a closed vessel, both the components of a binary solution would evaporate and eventually an equilibrium would be established between vapour phase and the liquid phase.
• The solute can be a gas, a liquid or a solid.
• Vapour pressure of liquid-liquid solutions is rationalised as the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution.
• Solubility of gases in liquids decreases with rise in temperature.
• Such solutions may contain one or more volatile components.
• We shall discuss the properties of only binary solutions, that is, the solutions containing two components, namely, the solutions of (i) liquids in liquids and (ii) solids in liquids.
• In this Section, we shall discuss the solutions of liquids and solids in a liquid.
• Dissolution process involves dynamic equilibrium and thus must follow Le Chatelier’s Principle.
• Solutions of gases in liquids have already been discussed in Section 1.3.2.
• Generally, the liquid solvent is volatile.
• For component 1, the partial vapour pressure is denoted as p 1 μ x 1 and for component 2, it is denoted as p 2 0 x 2.
• Liquid solutions are formed when solvent is a liquid.
• The French chemist, Francois Marte Raoult (1886) gave the quantitative relationship between the partial vapour pressures and the mole fractions, which is known as the Raoult’s law.
• The total vapour pressure at this stage is denoted as p total and the partial vapour pressures of the two components are denoted as p 1 and p 2 respectively.
• The solute may or may not be volatile.
• An example of a solution described by volume percentage is 10% ethanol solution in water, which means that 10 mL of ethanol is dissolved in water such that the total volume of the solution is 100 mL.
• Qualitatively, we can say that the solution is dilute (i.e., relatively very small quantity of solute) or it is concentrated (i.e., relatively very large quantity of solute).
• There are several ways by which we can describe the concentration of the solution quantitatively.
• Mass percentage (w/w) is a method to describe the concentration of a component in a solution by the mass of the component in the solution divided by the total mass of the solution.
• Mass by volume percentage (w/V) is another unit which is commonly used in medicine and pharmacy.
• Mole fraction (x) is a commonly used symbol for mole fraction and the subscript used on the right hand side of x denotes the component.
• Solutions containing liquids are commonly expressed in this unit, for example, a 35% (v/v) solution of ethylene glycol, an antifreeze, is used in cars for cooling the engine.
• In real life, these kinds of description can add to lot of confusion and thus the need for a quantitative description of the solution.
• Volume percentage (V/V) is a method to describe the concentration of a component in a solution by the volume of the component divided by the total volume of the solution.
• An example of a solution described by mass percentage is 10% glucose in water by mass, which means that 10 g of glucose is dissolved in 90 g of water resulting in a 100 g solution.
• Concentration described by mass percentage is commonly used in industrial chemical applications, for example, commercial bleaching solution contains 3.62 mass percentage of sodium hypochlorite in water.
• The freezing point depression constant of benzene is 5.12 K kg mol-1.
• 1.00 g of a non-electrolyte solute dissolved in 50 g of benzene lowered the freezing point of benzene by 0.40 K.
• Level of solution rises in the thistle funnel due to osmosis of solvent.