Acids & Bases

1. Acids & Bases They are everywhere.. In your food In your house EVEN IN YOU!!!!!

2. What is an acid? • An acid is a solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sour". • The more H+ or H3O+ ions, the more acidic the solution. • Also known as Arrehenius Acid • According to the “other theory” a proton (H+) donor

3. Properties of an Acid • Tastes Sour • Conduct Electricity • Corrosive, which means they break down certain substances. Many acids can corrode fabric, skin,and paper • Some acids react strongly with metals • Turns blue litmus paper red Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_bases_1.shtml

4. Uses of Acids • Acetic Acid = Vinegar • Citric Acid = lemons, limes, & oranges. It is in many sour candies such as lemonhead & sour patch. • Ascorbic acid = Vitamin C which your body needs to function. • Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics. • Car batteries

5. What is a base? • A base is a solution that has an excess of OH- ions. • Another word for base is alkali. • Bases are substances that can accept hydrogen ions • Also known as Arrehenius base • According to the “Other theory” a Proton (H+) acceptor

6. Properties of a Base • Feel Slippery • Taste Bitter • Corrosive • Can conduct electricity. (Think alkaline batteries.) • Do not react with metals. • Turns red litmus paper blue.

7. Uses of Bases • Bases give soaps, ammonia, and many other cleaning products some of their useful properties. • The OH- ions interact strongly with certain substances, such as dirt and grease. • Chalk and oven cleaner are examples of familiar products that contain bases. • Your blood is a basic solution.

8. Rules and Exceptions • Always check tables to see if substance is acid or base • Most acids have H in front • (except CO2) • Most bases have OH at end • (except NH3 and hydrocarbons followed by OH)

9. Not an acid, base or salt 2 nonmetals (covalent bonds) CH4 NO2 and alcohols: CH3OH, (methanol) CH3CH2OH (ethanol) This OH is NOT a BASE!!! (It’s an alcohol) Organic acids: vinegar (acetic acid) CH3COOH also written HC2H3O2

10. Vocabulary • Electrolytes • Indicator • Salt • Conducts electricity b/c of mobile ions (acid,base,salt)ABS • Substance that changes color in acids and bases • Metal + nonmetal or polyatomic ion but NO “H” or “OH” ( ionic bond)ex. NaCl Na+ + Cl-

11. Practice: Label the following as either: acid, base, salt, neither • HNO3 • LiOH • LiCl • KOH • HCl • NaNO3 • C3H8 • HI • CuCl2 • Ca(OH)3 • Mg(OH)3 • H3PO4 • KBr • FeI2 • C6H12O6 • NH3(aq) • CO2(aq) • CH3CH2OH

12. pH Scale • pHis a measure of how acidic or basic a solution is. • The pH scale ranges from 0 to 14. • Acidic solutions have pH values below 7 • A solution with a pH of 0 is very acidic. • A solution with a pH of 7 is neutral. • Pure water has a pH of 7. • Basic solutions have pH values above 7.

13. pH Scale • A change of 1 pH unit represents a tenfold change in the acidity of the solution. • For example, if one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.

14. Acid – Base Reactions • A reaction between an acid and a base is called neutralization. An acid-base mixture is not as acidic or basic as the individual starting solutions. • acid + base  salt + water • H+(aq) + OH-(aq)  HOH • (HOH is H2O)

15. The “Other Theory” • BAAD • Bases accept, acids donate • Acids • Proton (H+) donor • Bases • Proton (H+) acceptor • Example: • HCl + NH3 NH4+ + Cl- Acid Base Acid Base

16. Each pH unit is 10times as large as the previous one A change of 2 pH units means 100 times more basic or acidic x10 x100 The pH Scale

17. Weak acid, strong base Strong Acid Weak acid/base Strong Base Increasing H+ ions (H3O+) Increasing OH- ions (hydrogen/hydronium ions) (hydroxide ions)

18. 10 fold increase, 1/10 decrease OH- increases 10 fold, H3O+ decreases 1/10 H3O+ increases 10 fold, OH- decreases 1/10

19. Neutralization reactions • Are also double replacement reactions • Acid + base  salt + water • Outer ions combine, inner ions combine • HCl + NaOH NaCl + H2O • H2SO4 + 2KOH  K2SO4 + 2H2O

20. Example: Stomach antacids

21. Practice • 2. Complete and balance the following equations representing neutralization reactions: • 2 CsOH + H2CO3 • 2 HF + Mg(OH)2 • 3 HNO3 + Al(OH)3 • HCl + KOH  • HBrO3 + LiOH 

22. Practice key • Complete and balance the following equations representing neutralization reactions: • 2 CsOH + H2CO3 2H2O + Cs2CO3 • 2 HF + Mg(OH)22H2O +MgF2 • 3HNO3 + Al(OH)33H2O + Al(NO3)3 • = • HCl +KOHH2O +KCl • HBrO3+LiOH H2O + LiBrO3

23. Which salt is produced when sulfuric acid and calcium hydroxide react? • CaH2 • CaO • CaS • CaSO4

24. Sulfuric Acid, H2SO4, can be used to neutralize barium hydroxide, Ba(OH)2. What is the formula for the salt produced by this neutralization? • BaS • BaSO2 • BaSO3 • BaSO4

25. Titration: • A laboratory method for determining the concentration of an unknown acid or base using a neutralization reaction. • A standard solution,(a solution of known concentration), is used.

26. Equivalence Point • The point at which there are stoichiometrically equivalent amounts of acid and base. • [H+] = [OH-]

27. Buret Valve

28. https://www.youtube.com/watch?v=g8jdCWC10vQ Titration Acid with Phenolpthalein End-Point

30. Indicators • Indicators are chosen, such that they change colors at the range of the pH of interest. • The solution itself at the end-point may be: • Basic, if the reaction involves a strong base and a weak acid. • Neutral, if the reaction involves a strong acid and a strong base. • Acidic, if the reaction involves a strong acid and a weak base.

31. Methods of Solving Titration Problems: a) using stoichiometry b) using the titration formula MaVa=MbVb. https://www.youtube.com/watch?v=g8jdCWC10vQ

32. Ex. 1 What is the concentration of HCl if 30.0 mL of 0.10 M NaOH neutralizes 50.0mL HCl?

33. Ex. 2 A 20.0 mL solution of Sr(OH)2 is neutralized after 25.0 mL of standard 0.05 M HCl is added. What is the concentration of Sr(OH)2?

34. Ex. 3 • How many mL of 0.20 M H3PO4 are needed to neutralize 55.0 mL of a 0.10 M solution of NaOH?

35. Ex. 4 • What volume of 0.20M Ca(OH)2 will neutralize 45.0 mL of a 1M solution of HClO3?

36. Acids with Metals • Acids react with metals, bases do not • It is a single replacement reaction • Metal + acid  hydrogen gas + salt • Example Mg + 2HCl  H2 + MgCl2 • Example Zn + H2 SO4 H2 + ZnSO4

37. Identify which of the following are neutralization reactions, spontaneous acid + metal reactions (Use table J), or just a plain single replacement or double replacement. • ________________ a) Pb(NO3 )2 + KI  KNO3 + PbI • ________________ b) Zn + CuSO4  ZnSO4 + Cu • ________________ c) Mg + HCl  MgCl + H2 • ________________ d) H2 SO4 + NaOH  Na2 SO4 + H2 • ________________ e) Ag + H3 PO3  AgPO3 + H2 • ________________ f) Ca(OH) + HNO3  H2 O + Ca(NO3 )2 • ________________ g) LiCl + F2  LiF + Cl2 • ________________ h) NHO3 + Mg(OH)2  HOH + Mg(NO3 )2 • ________________ i) H3O+ + OH--  H2O

38. Acid – Base reactions • Each salt listed in this table can be formed by the reaction between an acid and a base.