Acids and Bases

Definitions of Acids Arrhenius Acid-any substance that produces hydrogen ions (H+) when dissolved in water. Bronsted Lowry acid-any substance that donates protons to form hydronium ions (H3O+) Examples of acids: HCl, HNO3, H2SO4, HC2H3O2

Electrolytes Solutions that conduct an electric current efficiently contain strong electrolytes. Strong electrolytes are substances that completely ionize in water. Acids that ionize completely and are classified as strong electrolytes are also classified as strong acids.

Strong acids The following are classified as strong acids: HCl, HBr, HI, H2SO4, HNO3,HClO3, HClO4 All other acids are classified as weak acids (they do not ionize completely in water). Note: a classification of strong vs weak acid is independent of the concentration-for example, a strong acid can be very dilute and a weak acid can be very concentrated.

Properties of Acids Taste sour React with metals Conduct electricity (to some degree based on strength) pH<7 Turn litmus red Turn phenolphthalein colorless

Definitions of Bases Arrhenius Base-any substance that produces hydroxide ions (OH-) when dissolved in water. Bronsted Lowry Base- any substance that accepts protons. Examples of bases: NaOH, Ca(OH)2, Mg(OH)2, NH3

Bases as electrolytes Bases are also classified as strong vs weak, based on the degree of ionization. The strong bases (strong electrolytes) are: (alkali metal hydroxides, Sr(OH)2 and Ba(OH)2 ) All other bases are classified as weak bases.

Properties of Bases Taste bitter Feel slippery Conduct electricity pH>7 Turn litmus blue Turn phenolphthalein pink

NaOH is an example of a(n) 10 Acid Base Neither 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

A substance that is a proton acceptor is a(n) 10 Acid Base neither 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

HCl is an example of a(n) Acid Base Neither 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Lemon juice is an example of a(n) Acid Base Neither 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

A substance that is a proton (H+) donor is an example of a(n) Acid Base Neither 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Drain cleaner is an example of a(n) Acid Base Neither 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Vinegar is an example of a(n) Acid Base Neither 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Water is an example of a(n) Acid Base Neither 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

A substance that turns litmus red is a(n) Acid Base Neither Both 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

A substance that conducts electricity is a(n) Acid Base Neither Both 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

pH Scale

Indicators and pH Indicators are substances that change color depending on the concentration of hydrogen ions (H+) in a solution. Litmus and phenolphthalein are examples of indicators. Indicators can be used to determine the pH of a solution.

A solution with a pH of 3 is 10 Acidic Basic Neutral 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Which of the following is an expected pH for a sample of lemon juice? 10 3 6 7 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

A substance with a pH of 12.7 is a(n) Acid Base Neither Both 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Neutralization Reactions Neutralization reactions occur when acids react with bases and produce a salt and water. A salt is an ionic compound consisting of the positive ion of the base and the negative ion of the acid. Example: HCl + NaOH  NaCl + H2O acid base salt water If the [H+] = [OH-], the resulting solution will be neutral (pH=7). Neutralization reactions are a specific type of double displacement reaction.

What salt is formed? HCl + KOH  H3PO4 + NaOH  Ca(OH)2 + H2SO4  Mg(OH)2 + HF  HNO3 + NaOH 

Titration A titration is a method for determining the concentration of a solution by reacting a known volume of that solution with a solution of known concentration. The reaction that takes place is a neutralization reaction.

Procedure for carrying out titrations. A measured volume of an acid or base is added to a beaker or flask. A buret is filled with a solution of known concentration (titrant). The solution of known concentration is added until the solution in the beaker has been completely neutralized. This point is called the equivalence point.