Ch. 20 Notes -- Acids and Bases

1. sour lemons Ch. 20 Notes -- Acids and Bases metals What makes something an acid? Acid Properties: (1) tastes _______-- _______________ (2) corrosive to _________ (3) contains [ ___ ] (or [ _____ ] = “_______________” ions) (4) proton ([ ___ ]) __________-- Brønsted-Lowry Theory Example: HCl + H2O  ______ + ______ H+ H3O+ hydronium H+ donor H3O+ Cl−

2. Properties of Bases What make something a base? Base Properties: (…the opposite of acid properties) (1) tastes ________ -- ___________ peel , parsley, dark chocolate (2) feels _____________ -- ________ (3) contains [ _____ ] ions (4) proton ([H+]) ______________-- Brønsted-Lowry Theory Example: NH3 + H2O  ______ + _______ bitter banana slippery soap OH− acceptor NH4+ OH−

3. pH of food Content Goal: Students will test pH to determine if household substances are an acid or a base. Language Goal: Students will show they know the material by filling out the paper that will be completed in class today Social Goal: Students will work together safely and will follow instructions so that everyone has equal access to lab materials.

4. Safety • No play fighting or any touching. • Move around the room in numerical order. • Please keep the beakers on the table. Do not move the beakers to you, move to the beakers. • Place used test strips into the waste beaker. • Wash your hands after the lab.

5. Common Acids citrus aspirin vinegar DNA Examples of Common Acids: Pepsi, _________ juices, ___________, stomach acid, battery acid, _____________, ______

6. Common Bases ammonia antacid baking soda • Examples of Common Bases: milk of magnesia, ___________, drain cleaner, soap, blood, ____________ tablets, ___________ ________.

7. Indicators colors • An indicator is a chemical that will change ___________ when placed in an acidic, basic or neutral environment. Indicator Colors For Acids • litmus paper = _______ • phenolphthalein = ___________ • red cabbage juice (universal indicator) = ________ • methyl orange = _______ red clear red red

8. Indicator Colors for Bases blue yellow • litmus paper = _______ • methyl orange = ____________ • red cabbage juice (universal indicator) =________ • phenolphthalein = ______ blue pink phenolphthalein Acid Base

9. Universal pH Paper : Indicator Colors Neutral Acidic Basic

10. Acid Vocabulary dissociates many H2SO4 HCl • strong acid - readily ___________ to produce ______ [H+] ions in water Examples: _________, HNO3, _______ • weak acid - produces a __________ amount of [H+] ions when in water Examples: HC2H3O2 (vinegar) , _________, _________ small H2CO3 lemon juice

11. Base Vocabulary dissociate many • strong base- readily __________ to produce ______ [OH−] ions in water Examples: NaOH , ________ • weak base- produces a __________ amount of [OH−] ions when in water Examples: _____ (ammonia); Mg(OH)2 (milk of magnesia) Other Vocabulary • _______________- another term for basic solutions • _______________- a substance that can act as both an acid and a base Examples: ___________ , ____________ KOH small NH3 Alkaline Amphoteric H2O HCO3−

12. Self-Ionization of Water neutral small • Pure water is _____________. It can ionize itself to form OH− and H3O+ ions in __________ amounts. H2O + H2O  H3O+ + OH− (or H2O  _______ + _______ ) • The universal indicator color is ___________ in neutral solutions. H+ OH− green self-ionization of water

13. Measuring the Amount of H+ and OH− Ions in a Solution pH concentration pOH OH− • _____ Scale- measures the _____________ of [H+] ions in a solution • _____ Scale- measures the concentration of [ ____ ] ions in a solution Formulas pH = − (log [H+]) pOH = −(log [OH−]) [H+] = 10−pH [OH−] = 10−pOH [H+] x [OH−] = 1 x 10−14 pH + pOH = 14 • With the pH scale, we have another way to define acids and bases: Acids have a pH _________7.0 Bases have a pH _________7.0 Neutral pH ___7.0 below above =

17. pH Testing

18. Alkalinity Testing

19. [H+] = 0.001 M So…pH = − (log 0.001 M) pH = 3 Practice Problems: 1) a) Calculate the pH of a 0.001 M HCl solution b) What is the pOH of this solution? c) What is the concentration of [OH−] ions in the solution? 2) a) Calculate the pOH of a NaOH solution that has a pH of 8.50 b) What is the [OH−] of this solution? c) What is the concentration of [H+] ions in the solution? pH + pOH = 14 So…14 − 3 = pOH pOH = 11 [OH−] = 10−pOH [OH−] = 10−11 Molaror 1 x 10−11 M pH + pOH = 14 So…14 − 8.5 = pOH pOH = 5.5 [OH−] = 10−pOH [OH−] = 10−5.5 Molar or 3.16 x 10−6 M [H+] = 10−pH [H+] = 10−8.5 Molar or 3.16 x 10−9 M

20. Neutralization Reactions salt When an acid and base are mixed, the reaction produces _______ and ___________. • If the initial concentrations and volumes of the reactants are equal, the products will be ____________... (pH= 7.0) • All neutralization reactions are ___________ replacement reactions. water neutral double H2O HX + M(OH)  ______ + ______ MX (“Salt”)

21. Titration concentration • Mixing an acid with a base to determine a __________________ is called “titration.” • An ____________ is used to determine when neutralization has occurred. • ________________ Solution- the solution of known concentration • ______ _________- the point of neutralization when titrating • At the ______ point, the moles of [H+] ions = moles of [OH−] ions. indicator Standard End Point end

22. Determining the Concentration of an Acid (or Base) by Titration (Macid)x(Vacid) = (Mbase)x(Vbase) Practice Problems: • A 25 mL solution of HNO3 is neutralized by 18 mL of 1.0 M NaOH standard solution using phenolphthalein as an indicator. What is the concentration of the HNO3 solution? (2) How many mL of 2.0 M KOH will it take to neutralize 55 mL of a 0.76 M HCl standard solution? ( ) x ( ) = ( ) x ( ) Macid 25 mL 1.0 M 18 mL Macid = 0.72 Molar ( ) x ( ) = ( ) x ( ) 0.76 M 55 mL 2.0 M Vbase Vbase = 20.9 mL