Compare and contrast acid and base properties. • Identify a substance as an acid or base • Identify acids and bases based on an indicator • Identify acids and bases based on their pH Key Words Acid Base Indicator Corrosive
ACID BASE Bitter (soap) DO NOT taste. Corrosive (burn) Destroy Acids (neutralization) Conduct electricity Feel slippery (destroy proteins & fats) Sour (lemons) Corrosive (burn) Destroy bases (neutralization) Conduct electricity React with most metals (hydrogen gas is made)
Acidic H Cl H 2SO4 H Br H NO3 Basic (alkaline) Na OH Ca( )2 K OH NH 3 OH
Most acids and bases are aqueous when used. Most acids and bases are ionic compounds and include polyatomic ions. Acids tend to have “H” in their formula. Bases often have polyatomic “OH” (hydroxide)- Usually bonded to a 1A or 2A metal. H NO3 Ca( )2 OH
HNO3 (s) (aq)+ NO3- (aq) H2CO3 (s) 2 (aq)+ CO3-2 (aq) Whendissolved in water, acids and bases dissociate into two ions. split apart into ions The hydrogen ion is responsible for the acid properties. H+ H+
Ca(OH)2 (s) Ca+2(aq) + 2 (aq) KOH(s) K+(aq) + (aq) The hydroxide ion is responsible for the base properties. OH- OH-
A substance that changes colour when added to an acid or base is called an indicator. There are many different types of indicators available. We often use paper containing the litmus dye as an indicator (red or bluelitmus paper).
Acids Bases Indicators Phenolphthalein Bromothymol blue Universal Indicator Methyl Orange Litmus RED Litmus BLUE (feeno-thay-leen)
Most acids contain hydrogen. • Most bases contain hydroxide (OH-) • Acids dissociate in water to make hydrogen ions. • Bases dissociate in water to make hydroxide ions. • Indicators are substances that change colour to show the presence of an acid or base.