Definitions [11]
Define the term solution.
A homogeneous mixture of two or more substances, whose relative amounts may be changed within certain limits, is called a solution.
Define isotonic solutions.
Two or more solutions exerting the same osmotic pressure are called isotonic solutions.
When two solutions are separated by a semipermeable membrane and no osmosis occurs, i.e., there is no net flow of water on either side through the membrane, the solutions are said to be isotonic solutions. If the membrane is perfectly semipermeable, the two solutions possess the same osmotic pressure and are also referred to as iso-osmotic solutions.
Define the term:
Ideal solution
It is characterised as a solution that adheres to Raoult's Law, with no interactions between the molecules and no volume or heat change during mixing.
For an ideal solution, Enthalpy of mixing of the pure components to form the solution is Δmix H = 0 and the volume of mixing is Δmix V = 0.
Define Normality.
Normality (N) of a solution is defined as the number of gram equivalents of the solute present in one liter of the solution. Normality is used in acid-based redox titrations.
Normality (N) = `"Number of gram equivalents of solute"/"Volume of solution in litre"`
Define Mass percentage.
The mass percentage of a component of a solution is defined as the mass of the solute in grammes present in 100 g of the solution. It is expressed as:
Mass % of a component = `"Mass of the component in the solution"/"Total mass of solution"xx100`
For example, if a solution is described as 10% glucose in water by mass, it 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, a commercial bleaching solution contains a 3.62 mass percentage of sodium hypochlorite in water.
Define Molality.
Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent. It is expressed as:
Molality (m) = `"Moles of solute"/"Mass of solvent in Kg"`
Therefore, the unit of molality is mole per kg (mol kg−1).
If nB moles of solute are dissolved in W grams of solvent, then
Molality = `"n"_"B"/"W" xx 1000`
Define Molarity (M).
Molarity (M) is defined as the number of moles of the solute dissolved in one Litre (or one cubic decimetre) of solution.
It is expressed as:
Molarity (M) = `"Moles of solute"/"Volume of Solution in Litre"`
For example, a 0.25 mol L−1 (or 0.25 M) solution of NaOH means that 0.25 mol of NaOH has been dissolved in one litre (or one cubic decimetre).
It is defined as the number of moles of solute present in 1000 mL of the solution. Molarity is represented by M.
Molarity (M) = `"Number of moles of solute"/"Volume of solution in mL" xx 1000`
or
M = `"Weight of solute"/"Molar mass of solute × Volume of solution in mL" xx 1000`
Define Mole fraction.
The mole fraction of a particular component in a solution is the ratio of the number of moles of that component to the total number of moles of all the components present in the solution.
Define molality.
Molality (m) is defined as the number of moles of the solute dissolved in one kilogram (Kg) of the solvent. The units of molality are moles per kilogram, i.e., mole kg−1. The molality is preferred over molarity if the volume of the solution is either expanding or contracting with temperature.
molality (m) = `"Number of mole of solute"/"mass of solvent (in kg)"`
What is a vapour pressure of liquid?
“The pressure exerted by the vapors above the liquid surface which is in equilibrium with the liquid at a given temperature is called vapor pressure”.
Define van’t Hoff factor.
The ratio of the observed (experimental) value of a colligative property to the normal (calculated) value of the same property is termed as van’t Hoff factor, i.
