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”1.List everything you know about acids.2.List everything you know about bases.3.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)
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
•HBr HBr (aq)(aq)
•HH22COCO33
•HH22SOSO33
hydrobromic acidhydrobromic acid
carbonic carbonic
acidacid
sulfurous sulfurous
acidacid
Acid Nomenclature Review
Some Properties of Bases
Produce OHProduce OH-- ions in water ions in water
Taste bitter, chalkyTaste bitter, chalky
Are electrolytesAre electrolytes
Feel soapy, slipperyFeel soapy, slippery
React with acids to form salts and waterReact with acids to form salts and water
pH greater than 7pH greater than 7
Turns red litmus paper to blue “Basic Turns red litmus paper to blue “Basic
Blue”Blue”
Some Common Bases
NaOHNaOH sodium hydroxidesodium hydroxide lyelye
KOHKOH potassium hydroxidepotassium hydroxide liquid soapliquid soap
Ba(OH)Ba(OH)22 barium hydroxidebarium hydroxide stabilizer for stabilizer for
plasticsplastics
Mg(OH)Mg(OH)22 magnesium hydroxidemagnesium hydroxide Milk of Milk of
magnesiamagnesia
Al(OH)Al(OH)33 aluminum hydroxidealuminum hydroxide Maalox (antacid)Maalox (antacid)
The pH scale is a way of The pH scale is a way of expressing the strength expressing the strength of acids and bases. of acids and bases. Instead of using very Instead of using very small numbers, we just small numbers, we just use the NEGATIVE power use the NEGATIVE power of 10 on the Molarity of of 10 on the Molarity of the Hthe H++ (or OH (or OH--) ion.) ion.
Under 7 = acidUnder 7 = acid 7 = neutral 7 = neutral
Over 7 = baseOver 7 = base
After today’s lesson, answer the following questions again…1.List everything you know about acids.2.List everything you know about bases.3.Which would you prefer to drink, a strong acid or a strong base-why?
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 10-47.6 X 10-74.22 X 10-6
Homework: Read pages 530-538 and answer questions 1-5 on page 538 (due Wednesday)
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
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 NaCl4 L of solution
Calculating the pHpH = - log [H+]
(Remember that the [ ] means Molarity)
Example: If [H+] = 1 X 10-10
pH = - log 1 X 10-10
pH = - (- 10)pH = 10
Example: If [H+] = 1.8 X 10-5
pH = - log 1.8 X 10-5
pH = - (- 4.74)pH = 4.74
pH calculations – Solving for H+pH calculations – Solving for H+What is the pH of a solution with What is the pH of a solution with
a concentration of 1.0 x 10a concentration of 1.0 x 106 6 M.M.
pH = - log [HpH = - log [H++]]
pH = - log [1.0 x 10pH = - log [1.0 x 10 6 6 M] M]
pH = 6pH = 6
pH = - log [HpH = - log [H++]]
pH = - log [1.0 x 10pH = - log [1.0 x 10 6 6 M] M]
pH = 6pH = 6
Let’s Practice
• Find the pH of the following solutions.
1. 1.0 x 10 -13 M2. 1.0 x 10 -2 M3. 2.4 x 10-5 M (log = -4.6)4. 8.6 x 10 -11 M (log= -10.1)
Estimate pH:A. 6.3 x 10 -11 MB. 1.3 x 10 -4 MC. 1.2 x 10-6 M D. 4.3 x 10 -9 MDetermine whether solution is an acid or base:A. 7.1 x 10 -3 MB. 4.3 x 10 -13 MC. 9.2 x 10-10 M D. 1.4 MThen, order all letters from most acidic to
most basic