pH Scale

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

Remember…..

As the H+ increases the pH level decreases

Neutralization

• A mixture of specific concentrations and amounts of acid and base to neutralize a reaction.

“Salt”

• Salt NaCl (Sodium Chloride) is not the only salt.• Salt is any compound created

from neutralizing an acid and a base. Water is also a byproduct of neutralization.