1. Acids and Bases Review

2. Behavior of many acids and bases can be explained by the Arrhenius theory. Arrhenius acids and bases are electrolytes.
Acids and bases are often composed of non-metals. All other organic molecules are not electrolytes.
An electrolyte is a substance which, when dissolved in water, forms a solution capable of conducting an electric current.
The ability of a solution to conduct an electric current depends on the number of ions.
Note that CH3OH and CH3CH2OH are not electrolytes, while NaOH and KOH are. Be clear on why this is so.

3. Arrhenius acids yield H3O+ (hydronium ion) as the only positive ion in an aqueous solution.
The common acids are found on Table K. Remember, organic acids are written R-COOH.
H+ and H3O+ are used interchangeably to describe acids.

4. Arrhenius acids react with active metals to produce hydrogen gas.
All of the metals above H2 on Table J will react with acid. The metals below, Cu, Ag, and Au are resistant to corrosion by acids.

5. Arrhenius bases yield OH- (hydroxide ion) as the only negative ion in aqueous solution.
The common bases are found on Table L.
All of them contain hydroxide ion except ammonia.
Ammonia occasionally steals a proton from water, creating hydroxide ion.
Ammonia acts as a proton acceptor. This is another way for defining a base. In this case, water is an acid, because it is acting as a proton donor.

6. In the process of neutralization, an Arrhenius acid and an Arrhenius base react to form a salt and water.
Note that neutralization reactions are a special form of double replacement. They are not redox reactions.
Note that the complete neutralization of a strong acid by a strong base will give a solution with pH 7.

7. Titration is a laboratory process in which a volume of solution of known concentrations is used to determine the concentration of another solution.
Titration problems are very common on the free response section.
Typically they will give you a data table, occasionally it will be a word problem.
Lately they have only been asking you to set up the calculation, not finish it.

8. The titration equation is found on Table T (back page).
If you get a word problem, carefully read the question and determine what your knowns are and unknown is.
If you get a table, you may have to do some subtraction to figure out the ml of acid or base used.

9. An aqueous solution of a salt conducts electricity
An aqueous solution of a salt conducts electricity. The solution can have a pH greater than, equal to, or less that 7.
Neutralization reactions always produce salts and water.
A “salt” in chemistry means any ionic compound, not just NaCl.

10. The acidity or alkalinity of a solution can be measured by its pH value. The relative level of acidity or alkalinity of a solution can be shown by using indicators.
Table M shows some common indicators and their color change region.
They will usually ask what the color of an indicator is at a specific pH.

11. The mathematical definition of pH is: pH= -log[H3O+].
On the pH scale, each decrease of one unit of pH represents a ten-fold increase in hydronium concentration.
The 10-fold increase per unit is a common question:
1 unit difference 10x
2 unit difference 100x
3 unit difference 1000x
The questions always involve a dramatic change in the pH of a solution, say from 5 to 8 or from 5 to 3.
They are usually accompanied by an indicator (Table M) question: “What color will thymol blue be at pH 5?

12. Which of the following are electrolytes?
a) NaCl(aq)
b) HBr (aq)
c) CH3OH(aq)
d) Ca(OH)2(aq)
e) C6H12O6 (aq)

13. What is an Arrhenius acid? What is an Arrhenius base?
When acid and base solutions are combined, what are the products?
HCl + KOH  KCl + H2O
Acid + base  salt + water

14. 15.0 ml of a 0.95 M solution of HNO3 is titrated with a NaOH solution of unknown concentration. The initial volume of base in the buret was ml. The final volume was ml. What is the concentration of the base?

15. In problem above, bromothymol blue was used as an indicator
In problem above, bromothymol blue was used as an indicator. What was the final color of the solution?
When the indicator changed color in the titration in question 4, a single drop raised the pH of the solution from pH 5 to pH 7. How much more basic was the solution after that drop was added?