Chemistry

• Solutions are homogenous mixtures of two or more substances, which may either be solids, liquids or gases. They are clear, have a variable composition, do not settle, can be separated by physical means and can be separated by filtration.
• Solutes are substances that can be dissolved in a solvent.
• Solvents are substances that can dissolve other substances.
• When the solute is present in small amounts, the

  solution is said to be dilute.
• When the solute is present in considerably significant

  amounts, the solution is said to be concentrated.
• Solubility is the maximum amount of solute that will dissolve in a solvent at a specific temperature.
• Henry’s law or Pressure-Solubility Law states that the solubility of a gas in a liquid is directly proportional to the pressure
• Surface area does not affect the amount of solute that will dissolve, but it does affect the solute’s rate of dissolution.
• The rate at which a solute dissolves can be increased by stirring the mixture.
• A saturated solution is one that contains as much of the solute as it can hold at a given temperature.
• An unsaturated solution contains less solute than it has the

  capacity to dissolve.
• The third type, the supersaturated solution contains more solute than is present in a saturated solution.
• The concentration of a solution is the amount of solute present in a given quantity of solvent or solution.
• Dilution is when water is added to a solution to decrease its concentration.
• The percent of the solute in the solution is referred to as percent composition. In expressing the percent concentration, the units mass or volume are used.
• Percent by mass of solute = mass of solute / mass of solution x 100%
• Percent by volume of solute = volume of solute / volume of solution x 100%
• Percent by weight-volume of solute = mass of solute / volume of solution x 100%
• If the pH is less than 7, the solution is considered acidic.
• If the pH is greater than 7, the solution is basic.
• At pH 7, the solution is said to be neutral.
• Mole fraction of component A = moles of A / sum of moles of all components
• Molarity (M) = moles of solute / liters of solution
• Molality (m) = moles of solute / mass of solvent (kg)
• Solutions can also be classified as diluted or concentrated according to relative amount of components present.
• Suspension is defined as fine particles of solid in a liquid and because it is transparent, it does not settle out and cannot be separated by filtration.
• Solutions are composed of solutes, the substance dissolved and the solvent, the liquid material in which the solute has dissolved.
• The solubility of a solute is affected by temperature, pressure, and nature of the solvent.
• The rate of dissolution is affected by surface area, rate of stirring and temperature.
• Increasing temperature usually increases the solubility of solid and liquid substances, and decreases the solubility of gases in water.
• A solution with more solute than solvent is called saturated.
• The greater the pressure, the greater the solubility of a gas in liquid.
• Pure science involves gathering information or the discovery of a pattern. When that information is applied to some use, it becomes technology.
• Chemistry is a central science that deals with the composition of matter, its structure and the changes in composition that this matter undergoes.
• Organic Chemistry is the study of the compounds of carbon. This branch of chemistry is important to the petrochemical, pharmaceutical and textile industries. All living organisms have traces of carbon.
• Inorganic Chemistry is the study of chemical elements and their compounds except carbon.
• Physical Chemistry deals with the relations between the physical

  properties of substances and their chemical formations along with their changes.
• Biochemistry is a science that is concerned with the composition and

  changes in the formation of living species.
• Analytical Chemistry deals mostly with the composition of substances. It seeks to improve means of measuring chemical composition of natural and artificial materials.
• Age of Alchemy – the chemistry of mining and purifying the metals gold, silver and copper.