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Acids and bases
• Acids and bases are of enormous importance in general chemistry, since they provide an effective way of understanding the properties of solutions and the chemical activity that lies within. Acid/base chemistry is central to:
• oxidation/reduction reactions • numerous bodily functions to maintain
homeostasis• play a crucial role in the environment
pH scale
• pH (potential of Hydrogen) is a measure of acidity or alkalinity (base). Substances are assigned a number according to the number of hydrogen H+ ions it contains.
• Scale of 0 to 14.
pH Scale• Acid: Less than 7. Adding hydrogen H+ ions• Base (alkaline): Greater that 7. Creates – OH ions
Why is water neutral? • Water (H2O) is the universal solvent and is
neutral with a pH of 7. • Water has as an equal balance of H+ ions and -
OH ions.
pH Scale
• A change on the scale of one (1) means a tenfold change in H+ concentration.• The value of pH is measured in
negative by the H+ concentration in moles per liter.
Properties of Acids
• Acids can be characterized by;– Sour taste– Sharp smell–Reacts with metals & carbonates– Examples: hydrochloric acid, nitric acid,
sulfuric acid, and citric acid
Properties of Bases
• Bases (Alkaline) can be characterized by;–Bitter taste– Slippery feel–Produces CO2
– Examples: sodium hydroxide, bleach, calcium hydroxide, & ammonia
Neutralization
• A mixture of specific concentrations and amounts of acid and base to neutralize a reaction.