1. Daily TAKS Connection: Concentration of Ions
IPC(9): The student knows how solution chemistry is a part of everyday life. The student is expected to:
(B) relate the concentration of ions in a solution to physical and chemical properties such as pH, electrolytic behavior, and reactivity.

2. Foldable Instructions
Construct a three tab foldable
Materials:
Foldable handout
Scissors
Pen
Colored pencils/crayons
Instructions:
Fold bottom paper along fold line at bottom edge
Color flap “Concentration of Ions in Solution”
Hotdog fold along center fold line
Cut along the dotted lines from edge to peak
Tuck the flaps into the bottom flap
Color flap labels

3. pH Notes Record the following notes under the flap label “pH” - Acidic
Neutral
Basic
pH < 7
pH = 7
pH > 7
[H+] > [OH-]
[H+] = [OH-]
[H+] < [OH-]
Litmus pink
Litmus blue
The greater the [H+], the stronger the acid
To raise pH value, add base: OH- ions
The greater the
[OH-], the stronger the base
To lower pH value, add acid: H+ ions
[H+]: when placed in brackets, this should be read – “the concentration of hydronium ions”

4. Question
Two clear solutions are placed in separate beakers. The first solution has a pH of 2, and the pH of the second solution is unknown. If the two solutions are mixed and the resulting pH is 4, the second solution must have —
a. A higher concentration of H+ ions
b. a higher concentration of OH– ions
Answer: B

5. Question
Two clear solutions are placed in separate beakers. The first solution has a pH of 10, and the pH of the second solution is unknown. If the two solutions are mixed and the resulting pH is 7, the second solution must have —
a. a higher concentration of H+ ions
b. a higher concentration of OH– ions
Answer: A

6. Question
Two clear solutions are placed in separate beakers. The first solution has a pH of 7 and the pH of the second solution is 5. If the two solutions are mixed, the resulting solution will have a pH —
a. greater than 7
b. less than 5
c. between 5 and 7
Answer: C

7. Electrolytic Behavior
Record the following notes under the flap labeled “Electrolytic Behavior” –
The greater the concentration of ions (from dissolved minerals and salts), the greater the electrolytic behavior
Better conductors of electricity
Pure water is not a good conductor
Must have dissolved minerals and salts to conduct electricity

8. Question
Bathwater normally has electrolytic behaviors even though distilled water does not. This is because bathwater —
a. contains isotopes of hydrogen
b. has been heated
c. is separated into H+ and OH– ions
d. contains dissolved minerals
Answer: D

9. Question In this apparatus, the distilled water is an example of a —
a. strong electrolyte
b. weak acid
c. nonelectrolyte
d. strong base
Answer: C

10. Question
Dissolving salt in water increases the conductivity of the solution because the —
a. salt gives the solution a net negative charge
b. salt ions bond with the available water molecules
c. solution has an increase in kinetic energy
d. concentration of ions in the solution increases
Answer: a; temperatures greater than 29.6°C will dissolve 31 grams or less of MTBE

11. Reactivity
Record the following notes under the flap labeled “Reactivity” –
The greater the concentration of ions in solution, the faster a chemical reaction will take place
Molarity indicates concentration; the greater the molarity of a solution, the greater the concentration of ions
Example: a 3M HCl solution has a greater concentration of ions than a 1M HCl solution.

12. Question
Which of the following pairs of solutions will demonstrate the greatest rate of reaction at 25°C?
1M HCl and 1M NaOH
2M HCl and 1M NaOH
1M HCl and 2M NaOH
2M HCl and 2M NaOH
Answer: D

13. Last Step Cut-out and glue the pH scale on the back of your foldable.
Use the More Acidic, More Basic, and Neutral labels along with the arrows to show what the numbers on the pH scale represent.
Cut-out the labels of common substances and place them on the pH scale in the correct order according to their level of pH.