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.

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

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”

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

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

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

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

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

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

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

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.

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

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.