Acids & Bases

1. 5/2/11: Turn in science fair ideas if you have them, please sit in new seats, check your grade as of 4/28 Objective: Describe the properties of acids and bases Catalyst (on paper today, leave room for an “exit slip”):For the following questions, use your prior knowledge. Do not worry if your answers are “right” List everything you know about acids. List everything you know about bases. Which would you prefer to drink, a strong acid or a strong base-why? Homework: Read pages 530-538 and answer questions 1-5 on page 538 (due Wednesday)

2. Acids & Bases

3. Some Properties of Acids • Produce H+ (as H3O+) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule) • Taste sour • Corrode metals • Electrolytes • React with bases to form a salt and water • pH is less than 7 • Turns blue litmus paper to red

4. Acid Nomenclature Review • HBr(aq) • H2CO3 • H2SO3  hydrobromic acid  carbonic acid  sulfurous acid

5. Name Them! Hydrochloric acid • HCl(aq) • H2SO4 • HNO3 Sulfuric Acid Nitric Acid

6. Some Properties of Bases • Produce OH- ions in water • Taste bitter, chalky • Are electrolytes • Feel soapy, slippery • React with acids to form salts and water • pH greater than 7 • Turns red litmus paper to blue “Basic Blue”

7. Some Common Bases NaOH sodium hydroxide lye KOH potassium hydroxide liquid soap Ba(OH)2 barium hydroxide stabilizer for plastics Mg(OH)2 magnesium hydroxide Milk of magnesia Al(OH)3 aluminum hydroxide Maalox (antacid)

8. The pH scale is a way of expressing the strength of acids and bases. Instead of using very small numbers, we just use the NEGATIVE power of 10 on the Molarity of the H+ (or OH-) ion.Under 7 = acid 7 = neutralOver 7 = base

9. pH of Common Substances

10. After today’s lesson, answer the following questions again… List everything you know about acids. List everything you know about bases. Which would you prefer to drink, a strong acid or a strong base-why?

11. 5/3/11: Objective: Describe how pH can be found from the amount of H+ in solution. Catalyst: Why is scientific notation useful? Write the following numbers in regular notation: 1.3 X 10-4 7.6 X 10-7 4.22 X 10-6 Homework: Read pages 530-538 and answer questions 1-5 on page 538 (due Wednesday)

12. Molarity Concentration In order to determine the concentration of a solution, simply take the number of moles of solute divided by the Liters of solution. M = Moles of solute Liters of solution

13. Example • If a 2 mole solution of NaCl were dissolved in 4 L of solution, what would be the concentration of NaCl? Answer: 2 mole NaCl = 0.5 M NaCl 4 L of solution

14. Calculating thepH pH = - log [H+] (Remember that the [ ] means Molarity) Example: If [H+] = 1 X 10-10pH = - log 1 X 10-10 pH = - (- 10) pH = 10 Example: If [H+] = 1.8 X 10-5pH = - log 1.8 X 10-5 pH = - (- 4.74) pH = 4.74

15. pH calculations – Solving for H+ What is the pH of a solution with a concentration of 1.0 x 106 M. pH = - log [H+] pH = - log [1.0 x 10 6 M] pH = 6

16. Let’s Practice • Find the pH of the following solutions. 1. 1.0 x 10 -13 M • 1.0 x 10 -2 M • 2.4 x 10-5 M (log = -4.6) • 8.6 x 10 -11 M (log= -10.1)

17. Estimate pH: 6.3 x 10 -11M 1.3 x 10 -4M 1.2 x 10-6 M 4.3 x 10 -9 M Determine whether solution is an acid or base: 7.1 x 10 -3M 4.3 x 10 -13M 9.2 x 10-10 M 1.4 M Then, order all letters from most acidic to most basic