The Nature and Properties of Solutions
INTRODUCTION
The experiment aimed to describe the various ways of expressing the concentration of solutions; prepare solutions of definite concentrations from standard substances by dilution and solve problems involving preparation of solutions and their concentrations.
BACKGROUND INFORMATION
A solution is any homogenous mixture of two or more substances, the relative properties of which may vary within certain limits. The two components of solutions are the solute (substance being dissolved) and the solvent (substance that does the dissolving). The maximum amount of solute which can be dissolved in 100 g of a given amount of solvent at a specified temperature is called solubility. There are ways of increasing the solubility of solutes: pulverizing (reducing the size of solid solutes), heating (increasing the temperature), and agitation (stirring).
The concentration of a substance in a solution is the quantity of the substance in a given quantity of the solution or solvent. There are qualitative ways of expressing concentration such as: diluted, concentrated, saturated, unsaturated and supersaturated. While the quantitative ways could be express as:
Percentage by weight = mass of solute X 100 Total mass of sol’n
Percentage by volume = volume of solute X 100 Total volume of sol’n
Molarity (M) of the solution is defined as the number of moles of solute present in a liter of the solution.
Molarity = mol of solute L of sol’n
The Normality (N) of the solution is defined as the number of equivalent weights of the solute in 1 L of solution.
Normality = equivalent of solute L sol’n
The molality (m) of solute is the number of moles solute per 1000g solvent or 1kg solvent.
Molality = mol of solute Kg solvent
The composition of a mixture is often expressed as the mole fraction (X) of each
References: Laboratory Manual for General Inorganic Chemistry Volume II (Chemistry 20) Microsoft Student with Encarta Premium 2009 www.Wikipedia.org