Work hard. Be nice. 100% EVERYDAY. Name: Period: Date: UNIT 13: Acids and Bases Lesson 2: ph!

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1 Name: Period: Date: UNIT 13: Acids and Bases Lesson 2: ph! By the end of today, you will have an answer to: How does ph determine how acidic or basic a solution is? Do Now: 1) How do the presence of acids and bases change the amount of H + dissolved in the water. Acids: Bases: Blast from the past: Catalyzing thoughts: Strong vs. Weak Strong acids (or base): Weak acids (or base): Hydrochloric acid (Table K formula: ) Ethanoic acid (Table L formula: ) Strong acid Draw particle diagrams above Weak acid Draw particle diagrams above Put it all together: Strong acids and strong bases are different from weak acids and weak bases because:

2 ph scale: ph is a measure of the concentration of H + ions or OH - ions in a solution. Concentration same as Molarity, so ph is also dependent on the molarity of a solution. What is the meaning of neutral? ACID BASE Fill in the blanks in the table below. Acid, Base, or Neutral? Possible ph a. 4 b. Neutral c. 8 d. Base NEUTRAL What does ph value mean? The more H + or H 3O + ions there are (higher the concentration of H + or H 3O + ) the more it will be the the ph value The more OH - ions there are (higher the concentration of OH - ) the more it will be the the ph value Quick Practice: 1) For each of the questions below, circle the option that will have the higher ph. a. Solution with H + concentrations of 0.43M or 0.57M b. Solution with OH - concentrations of 2.4M or 1.9M c. Solution with H + concentrations of 1.2M or 3.2M d. Solution with OH - concentrations of 4.3M or 4.4M 2) For each of the questions below, circle the option that will have the lower ph. a. Solution with H + concentrations of 0.19M or 0.23M b. Solution with OH - concentrations of 5.6M or 5.25M c. Solution with H + concentrations of 9.9M or 8.6M d. Solution with H + concentration of 1.2M or 3.2M *Each change of a single ph unit signifies a tenfold change in the concentration of the hydrogen ion or the hydroxide ion. The [H + ] (concentration of H + or H 3O + ions) is ten times greater in a solution with a ph of 5 as in a solution with a ph of 6. --How many times greater is the H + concentration of ph 4 than ph 7? The [OH - ] (concentration of OH - ions) is 100 times greater in a solution with a ph of 11 as in a solution with a ph of 9. --How many times less is the OH - concentration of ph 8 than ph 11?

3 CW 13.2 ph 10 points Part I: State which solution at the given ph value has the greatest amount of hydrogen ions and by how much. 1. ph of 1 versus ph of 2 2. ph of 8 versus ph of 9 Part II:State which solution at the given ph value has the greatest amount of hydroxide ions and by how much. 3. ph of 10 versus ph of ph of 3 versus ph of 6 More practice: 5. If the ph is 3, is there more H 3O + ions or OH - ions? How do you know? 6. If the ph is 9, is there more H 3O + ions, or OH - ions? How do you know? 7. As the ph decreases from 6 to 5, what happens to the concentration of hydronium ions? Hydroxide ions? Hydrogen ions: Hydroxide ions: 8. As the ph drops from 6 to 3? Hydrogen ions: Hydroxide ions: As the ph increases from 6 to 9, what happens to H + ion concentration? OH - ion concentration? Hydrogen ions: Hydroxide ions:

4 Regents Questions: Answer the following questions. 1. A hydrogen ion, H+, in aqueous solution may also be written as (1) H 2O (2) H 3O + (3) H 2O 2 (4) OH - 2. As the ph of a solution is changed from 3 to 6, the concentration of hydronium ions (1) increases by a factor of 3 (2) increases by a factor of 1000 (3) decreases by a factor of 3 (4) decreases by a factor of Solution A has a ph of 3 and solution Z has a ph of 6. How many times greater is the hydronium ion concentration in solution A than the hydronium ion concentration in solution Z? (1) 100 (2) 3 (3) 2 (4) Which statement correctly describes a solution with a ph of 9? (1) It has a higher concentration of H 3O + than OH - (2) It has a higher concentration of OH - than H 3O + (3) It has the same concentration of H 3O + as of OH - Part II: Free Response Base your answer to question 5 on the passage below. A student was studying the ph differences in samples from two Adirondack streams. The student measured a ph of 4 in stream A and a ph of 6 in stream B. 5. Compare the hydronium ion concentration in stream A to the hydronium ion concentration in stream B. Base your answer to question 6 on the passage below. Three bottles of liquids labeled 1, 2, and 3 were found in a storeroom. One of the liquids is known to be drain cleaner. Drain cleaners commonly contain KOH or NaOH, both strong bases. The ph of each liquid at 25 C was determined with a ph meter. The table below shows the test results. 6. Explain how the ph results in this table enable a student to correctly conclude that bottle 3 contains the drain cleaner. Base your answer to number 7 on the passage below. A truck carrying concentrated nitric acid overturns and spills its contents. The acid drains into a nearby pond. The ph of the pond water was 8.0 before the spill. After the spill, the pond water is 1,000 times more acidic. 7. What is the new ph of the pond water after the spill?

5 Exit Ticket Quiz 13.2 ph 3 points Consider two solutions, one with a ph of 1 and one with a ph of Do the two solutions have more hydrogen ions or hydroxide ions? 2. Which of the solutions has a greater hydrogen ion concentration? 3. How many times greater is the hydrogen ion concentration? Exit Ticket Quiz 13.2 ph 3 points Consider two solutions, one with a ph of 1 and one with a ph of Do the two solutions have more hydrogen ions or hydroxide ions? 2. Which of the solutions has a greater hydrogen ion concentration? 3. How many times greater is the hydrogen ion concentration?

6 HW 13.2 ph 10 points Directions: As you read the passages, please UNDERLINE important information and WRITE DOWN THE KEY IDEAS for every paragraph on the right of the passage. Then, answer the questions based on the information. QUESTION 1: The health of a fish depends on the amount of oxygen dissolved in the water. A dissolved oxygen (DO) concentration between 6 parts per million and 8 parts per million is best for fish health. A DO concentration greather than 1 part per million is necessary for fish survival. Fish health is also affected by water temperature and concentrations of dissolved ammonia, hydrogen sulfide, chloride compounds, and nitrate compounds. Most freshwater fish thrive in water with a ph between 6.5 and 8.5. A student s fish tank contains fish, green plans, and 3800 grams of fish-tank water with 2.7 x 10-2 gram of dissolved oxygen. Phenolphthalein tests colorless and bromthymol blue tests blue in samples of fishtank water. 1. What is the overall point of this passage? 2. When the fish-tank water has a ph of 8.0, the hydronium ion concentration is 1.0 x 10-8 mole per liter. What is the hydronium ion concentration when the water has a ph of 7.0? HW 13.2 ph 10 points Directions: As you read the passages, please UNDERLINE important information and WRITE DOWN THE KEY IDEAS for every paragraph on the right of the passage. Then, answer the questions based on the information. QUESTION 1: The health of a fish depends on the amount of oxygen dissolved in the water. A dissolved oxygen (DO) concentration between 6 parts per million and 8 parts per million is best for fish health. A DO concentration greather than 1 part per million is necessary for fish survival. Fish health is also affected by water temperature and concentrations of dissolved ammonia, hydrogen sulfide, chloride compounds, and nitrate compounds. Most freshwater fish thrive in water with a ph between 6.5 and 8.5. A student s fish tank contains fish, green plans, and 3800 grams of fish-tank water with 2.7 x 10-2 gram of dissolved oxygen. Phenolphthalein tests colorless and bromthymol blue tests blue in samples of fishtank water. 1. What is the overall point of this passage? 2. When the fish-tank water has a ph of 8.0, the hydronium ion concentration is 1.0 x 10-8 mole per liter. What is the hydronium ion concentration when the water has a ph of 7.0?

7 QUESTION 2: In liquid water, an equilibrium exists between H 2O (l) molecules, H + (aq) ions, and OH - (aq) ions. A person experiencing acid indigestion after drinking tomato juice can ingest milk of magnesia to reduce the acidity of the stomach contents. Tomato juice has a ph value of 4. Milk of magnesia, a mixture of magnesium hydroxide and water, has a ph value of What is the overall point of this passage? 4. Complete the equation below for the equilibrium that exists in liquid water. H 2O (l) + 5. Compare the hydrogen ion concentration in tomato juice to the hydrogen ion concentration in milk of magnesia. 6. Identify the negative ion in milk of magnesia. QUESTION 2: In liquid water, an equilibrium exists between H 2O (l) molecules, H + (aq) ions, and OH - (aq) ions. A person experiencing acid indigestion after drinking tomato juice can ingest milk of magnesia to reduce the acidity of the stomach contents. Tomato juice has a ph value of 4. Milk of magnesia, a mixture of magnesium hydroxide and water, has a ph value of What is the overall point of this passage? 4. Complete the equation below for the equilibrium that exists in liquid water. H 2O (l) + 5. Compare the hydrogen ion concentration in tomato juice to the hydrogen ion concentration in milk of magnesia. 6. Identify the negative ion in milk of magnesia.