Section 3.4

Acids are chemicals in which the positive ion is a hydrogen atom.  for example; HCl or H 2 SO 4  When mixed with water they produce a free hydrogen ion that combines with a water molecule to produce a hydronium ion (H 3 O) H +1 + H 2 O  H 3 O +1  An acid is a substance that releases hydrogen ions when it breaks apart in water.

1. Taste sour 2. React with metals to produce hydrogen 2HCl + 2Na  2NaCl + H 2 3. Conduct electricity.

 Bases are substances in which the negative ion is an ion called hydroxide (OH) -1.  For example; NaOH, or KOH  used to make soap, household cleaners, fertilizers, and explosives.

1. Taste bitter 2. Feel slippery 3. Conduct electricity 4. Sometimes Caustic. That is they eat away at certain substances and they are irritating or damaging to skin.

 A salt is a compound formed from the positive metal ions of a base and a negative nonmetal ion of an acid.  For example NaCl, K 2 SO 4  Are the product of a reaction between an acid and a base, along with water.

 They form crystals when in solid form  They usually have a higher hardness because of their ionic bonding.  An acid plus a base yields a salt and water. HCl + NaOH  NaCl + HOH or HCl + NaOH  NaCl + H 2 O

 After neutralization, an acid-base mixture is not as acidic or basic as the individual starting solutions were.  The final pH depends on such factors as the volumes, concentrations, and identities of the reactants. For example, some acids and bases react to form products that are not neutral. If only a small amount of strong base is reacted with a much larger amount of strong acid, the solution will remain acidic.  In a neutralization reaction, an acid reacts with a base to produce a salt and water

 the scale ranges from 0 to 14  acids range from 0 to 7, with 0 being the strongest acid  bases range from 7 to 14, with 14 being the strongest base.  pure water, which is neither acid nor base, has a pH level of 7 or is neutral

 The pH scale gives a measure of the concentration of positive hydrogen ions in a solution.  A low pH tells you that the concentration of hydrogen ions is high. In contrast, a high pH tells you that the concentration of hydrogen ions is low.  a way of describing the acidic or basic strength of a solution.  the acidity of a solution can be expressed by using the pH scale

 Indicators are substances that visibly show a change in the nature of a chemical system.  Universal indicator- an acid/base indicator that shows, by color, the pH of a substance. ACIDICNEUTRALBASIC