5.1B Acids and Bases (Part 2)

1. Acids can sometimes be identified by their formula a. Some substances will act as an acid only when dissolved in water, e.g HCl (aq) b. Most acids begin with hydrogen, e.g. HCl, H2S, H2SO4, HF i. The main exception are the organic acids which contain carbon, e.g. CH3COOH (aq)

2. Naming acids Non-oxy acids Oxy acids HCl, HNO3 HBr H2SO4, HI H3PO4 a. There are two major groups of acids i. Non-oxy acids which are usually binary compounds, hydrogen and one other element, e.g. HCl, HBr, HI ii. Oxy acids which contain oxygen in the negative polyatomic ion, e.g. HNO3, H2SO4, H3PO4 Non-oxy acids Oxy acids HCl, HNO3 HBr H2SO4, HI H3PO4

b. Non oxy-acids names i. begin with “hydro” ii. change the ending of the negative ion name to “ic” Formula Formula in solution Chemical Name Acid name HCl HCl (aq) HBr HBr (aq) H2S H2S(aq) H3P H3P (aq)

b. Non oxy-acids names i. begin with “hydro” ii. change the ending of the negative ion name to “ic” Formula Formula in solution Chemical Name Acid name HCl HCl (aq) Hydrogen chloride Hydrochloric acid HBr HBr (aq) H2S H2S(aq) H3P H3P (aq)

b. Non oxy-acids names i. begin with “hydro” ii. change the ending of the negative ion name to “ic” Formula Formula in solution Chemical Name Acid name HCl HCl (aq) Hydrogen chloride Hydrochloric acid HBr HBr (aq) Hydrogen bromide Hydrobromic acid H2S H2S(aq) H3P H3P (aq)

b. Non oxy-acids names i. begin with “hydro” ii. change the ending of the negative ion name to “ic” Formula Formula in solution Chemical Name Acid name HCl HCl (aq) Hydrogen chloride Hydrochloric acid HBr HBr (aq) Hydrogen bromide Hydrobromic acid H2S H2S(aq) Hydrogen sulphide Hydrosulphuric acid H3P H3P (aq)

b. Non oxy-acids names i. begin with “hydro” ii. change the ending of the negative ion name to “ic” Formula Formula in solution Chemical Name Acid name HCl HCl (aq) Hydrogen chloride Hydrochloric acid HBr HBr (aq) Hydrogen bromide Hydrobromic acid H2S H2S(aq) Hydrogen sulphide Hydrosulphuric acid H3P H3P (aq) Hydrogen phosphide Hydrophosphoric acid

c. Oxy-acids names i. If the original negative polyatomic ion ended with “ate”, change the ending to “ic” ii. If the original negative polyatomic ion ended with “ite”, change the ending to “ous” Formula Formula in solution Chemical Name Acid name HNO3 HNO3 (aq) H2SO4 H2SO4 (aq) H3PO4 H3PO4 (aq) H2SO3 H2SO3 (aq) HNO2 HNO2 (aq)

c. Oxy-acids names i. If the original negative polyatomic ion ended with “ate”, change the ending to “ic” ii. If the original negative polyatomic ion ended with “ite”, change the ending to “ous” Formula Formula in solution Chemical Name Acid name HNO3 HNO3 (aq) Hydrogen nitrate Nitric acid H2SO4 H2SO4 (aq) H3PO4 H3PO4 (aq) H2SO3 H2SO3 (aq) HNO2 HNO2 (aq)

c. Oxy-acids names i. If the original negative polyatomic ion ended with “ate”, change the ending to “ic” ii. If the original negative polyatomic ion ended with “ite”, change the ending to “ous” Formula Formula in solution Chemical Name Acid name HNO3 HNO3 (aq) Hydrogen nitrate Nitric acid H2SO4 H2SO4 (aq) Hydrogen sulphate Sulphuric acid H3PO4 H3PO4 (aq) H2SO3 H2SO3 (aq) HNO2 HNO2 (aq)

c. Oxy-acids names i. If the original negative polyatomic ion ended with “ate”, change the ending to “ic” ii. If the original negative polyatomic ion ended with “ite”, change the ending to “ous” Formula Formula in solution Chemical Name Acid name HNO3 HNO3 (aq) Hydrogen nitrate Nitric acid H2SO4 H2SO4 (aq) Hydrogen sulphate Sulphuric acid H3PO4 H3PO4 (aq) Hydrogen phosphate Phosphoric acid H2SO3 H2SO3 (aq) HNO2 HNO2 (aq)

c. Oxy-acids names i. If the original negative polyatomic ion ended with “ate”, change the ending to “ic” ii. If the original negative polyatomic ion ended with “ite”, change the ending to “ous” Formula Formula in solution Chemical Name Acid name HNO3 HNO3 (aq) Hydrogen nitrate Nitric acid H2SO4 H2SO4 (aq) Hydrogen sulphate Sulphuric acid H3PO4 H3PO4 (aq) Hydrogen phosphate Phosphoric acid H2SO3 H2SO3 (aq) Hydrogen sulphite Sulphurous acid HNO2 HNO2 (aq)

c. Oxy-acids names i. If the original negative polyatomic ion ended with “ate”, change the ending to “ic” ii. If the original negative polyatomic ion ended with “ite”, change the ending to “ous” Formula Formula in solution Chemical Name Acid name HNO3 HNO3 (aq) Hydrogen nitrate Nitric acid H2SO4 H2SO4 (aq) Hydrogen sulphate Sulphuric acid H3PO4 H3PO4 (aq) Hydrogen phosphate Phosphoric acid H2SO3 H2SO3 (aq) Hydrogen sulphite Sulphurous acid HNO2 HNO2 (aq) Hydrogen nitrite Nitrous acid

3. The formulas of bases can usually be identified by the hydroxide group (OH) a. E.g. Ca(OH)2, NaOH, KOH b. Bases may also have more common names c. Solutions of highly reactive bases are called caustic solutions i. Caustic solutions can burn human skin and tissue ii. Solutions of highly reactive acids are called corrosive solutions

Formula Chemical name Common name NaOH Mg(OH)2 Ca(OH) 2

Formula Chemical name Common name NaOH Sodium hydroxide Caustic soda, lye Mg(OH)2 Ca(OH) 2

Formula Chemical name Common name NaOH Sodium hydroxide Caustic soda, lye Mg(OH)2 Magnesium hydroxide Milk of magnesia Ca(OH) 2

Formula Chemical name Common name NaOH Sodium hydroxide Caustic soda, lye Mg(OH)2 Magnesium hydroxide Milk of magnesia Ca(OH) 2 Calcium hydroxide Hydrated lime

4. Another way of defining acids and bases is by the types of ions that they produce a. an acid is a compound that produces hydrogen (H+) ions in solution i. HCl(aq)  H+(aq) + Cl-(aq) ii. H2SO4(aq)  2H+ (aq) + SO42- (aq) b. A base is a compound that produces hydroxide (OH-) ions in solution i. NaOH(aq)  Na+(aq) + OH- (aq) ii. Mg(OH)2(aq)  Mg2+(aq) + 2OH- (aq)

5. pH can be seen as a measure of the concentration of hydrogen ions in a solution a. concentration refers to the number of hydrogen ions in a specific volume (usually litres) of solution b. a highly acidic solution will have a i. low pH ii. a high concentration of hydrogen (H+) ions c. highly basic/alkaline solution will have a i. high pH ii. a high concentration of hydroxide (OH-) ions

c. It is impossible for a solution to have both high hydrogen and hydroxide ion concentrations i. The two ions react together to form water ii. H+ + OH-  H2O d. If an acid and a base are mixed together, the two solution can neutralize each other i. Acid + base  salt + water ii. HCl + NaOH  NaCl + H2O