Physical Science Chapter 9: Families of Chemical Compounds
9-1 Acids and Bases
All acids and bases have certain physical and chemical properties when dissolved in water.
" sour taste
" indicators change colors (litmus paper turns red)
" react with metals to form hydrogen gas and metal compounds
" react with bases to form salt and water
" contain hydrogen
Acids contain hydrogen and in water an acid will produce hydrogen ions (H+)
Acids are proton donors
H+ in water forms the hydronium ion: H3O+
Common acids: sulfuric H2SO4 (Strong)
nitric HNO3 (Strong)
hydrochloric HCl (Strong)
citric acid (in orange juice)
" bitter taste
" litmus paper turns blue
" dissolve fats and oils
" react with acids to produce salts and water
Bases contain the hydroxide ion: OH-
The (OH- ) hydroxide ion can combine with (H+) hydrogen ions so bases are defined as proton acceptors.
potassium hydroxide KOH (Strong)
sodium hydroxide NaOH (Strong)
calcium hydroxide Ca(OH)2
*drain cleaners and antacids
Acids and Bases and Electrical Conductivity: They are conductive due to the presence of ions in the solution. (Acid has H+ ions, bases have OH- ions.)
Strong acid/bases are good electrolytes.
Weak acid/bases are poor electrolytes.
Acids and Bases Indicators:
Litmus paper, pH meter, pH paper, pehnolphthalein
9-2 Acids and Bases in Solution: Salts
The pH scale is used to measure the acidity of a solution. The strength of an acid or base depends on how completely a compound is pulled apart to form ions when dissolved in water.
The pH of a solution is a measure of the hydronium ion (H3O+) concentration.
pH goes from 0 to 14
pH 7 is neutral (Water)
<7 is an acid >7 is a base
(1 is most acidic) (14 is most basic)
Acid plus Base is a "neutralization" chemical reaction.(Always produce salt and water)
The products of an acid and a base are salt and water. Many salts formed as a result of a neutralization reaction are not soluble in water so they crystallize out of solution. They are called precipitates.