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Acids, Bases and Salts Acid-Base Theories

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Presentation on theme: "Acids, Bases and Salts Acid-Base Theories"— Presentation transcript:

1 Acids, Bases and Salts Acid-Base Theories
CHAPTER 15 PA

2 What is an Acid? The term acid comes from the Latin term acere, which means "sour". ex. Lemon juice, vinegar, and many other foods taste sour.

3 Acids Bases Taste sour Corrosive React with some metals to produce H2
Change Litmus to red acid= red React with bases to form water and salt. Bases taste bitter Feel slippery Corrosive Change Litmus to blue base = Blue Become less basic when mixed with acids.

4 Always Use Ref. Tables (vinegar)

5 Table L Common Bases Formula Name NaOH(aq) sodium hydroxide
KOH(aq) potassium hydroxide Ca(OH)2(aq) calcium hydroxide NH3(aq) aqueous ammonia

6 Svante Arrhenius Swedish chemist, proposed theories of electrolytic disassociation (acids/bases) and greenhouse effect.

7 Arrhenius Theory of Acids & Bases
Acid - produces hydrogen ion (H+) in a solution. HA  H+ + A¯ Base – produces hydroxide ion (OH¯) in a solution. XOH  X+ + OH¯

8 Nature of the Hydrogen Ion or Proton
Proton is so small that does not exist isolated in water. H+ + H2O  H3O + Hydronium Ion

9 Nature of Hydroxide Ion
The presence of OH- makes the substance an electrolyte and a base. Alcohols contain the OH group but are NOT IONIC COMPOUNDS therefore alcohols are NOT bases. C H O are molecular compounds NOT ionic compounds!!!!

10 HOW TO NAME ACIDS OUS if ion ends ITE IC if ion ends in ATE
NO OXYGEN IN FORMULA HYDRO ACID HCl Hydrochloric acid HBr Hydrobromic acid HF Hydrofluoric acid H2S Hydrosulfuric acid OXOA CIDS CONTAIN OXIGEN IN FORMULA ENDING OUS if ion ends ITE IC if ion ends in ATE Use table E

11 Solutions of Ionic Compounds conduct electricity = Electrolytes
Electrolytes – ions (charged particles) in solution. HCl(aq)  H+ + Cl- Hydrochloric Acid H+ Cl -

12 Solutions Electrolytes – conduct electricity when dissolved in H2O
; Release OH- (aq) Metal (+) and Non-Metal (-)

13 Solutions = Salts (ionic), acids, & bases Salts = ionic (+) (-)
bright dim dark Salts = ionic (+) (-) Strong Acid & Base Weak Acid or Weak Base Covalent = no ions

14 Conductivity apparatus Electrolytes – conduct electricity when dissolved in water

15 STRONG ACIDS COMPLETELY DISSOCIATED
If the solution is 2 M, 2 mol of H + and 2 mol of Cl-

16 WEAK ACIDS Partially dissociated. Molecules stay together and only some of them dissociate.

17 Strong Acids Strong Bases
HI HBr HCl HNO3 H2SO4 HClO4 LiOH NaOH KOH RbOH CsOH

18 Naming Acids

19 Binary Acids - composed of hydrogen + 1 other element Ex
Binary Acids - composed of hydrogen + 1 other element Ex. HCl Hydrochloric Acid Binary Acids begin with “hydro -” followed by name of other element; modified with an ending of “-ic”

20 Ternary Acids - molecular (covalent) - composed of hydrogen +
Ternary Acids - molecular (covalent) - composed of hydrogen + oxygen containing polyatomic ion (Ref. E) Ex. HNO3 Nitric Acid (NO31- Nitrate ion) HNO2 Nitrous Acid (NO21- Nitrite ion) H2SO4 Sulfuric Acid (SO42- Sulfate ion) Ternary Acids = Anion suffix (-ate or -ite) is dropped and replaced with “-ic” or “-ous” respectively.

21 TABLE M common acids HCl(aq) hydrochloric acid HNO3(aq) nitric acid
H2SO4(aq) sulfuric acid H3PO4(aq) phosphoric acid H2CO3(aq) carbonic acid CH3COOH(aq) ethanoic acid HC2H3O2(aq) (acetic acid)

22 Common Acids – Ref. K Nitric acid (HNO3) Hydrochloric acid (HCl)
1)  Most is used to make fertilizer 2)  Well known for making explosives Hydrochloric acid (HCl) 1)  Most is used to clean metals (pickling) 2)  Also called muriatic acid Sulfuric acid (H2SO4) 1)  The most widely used chemical in the world 2)  Most of it is used to make fertilizer 3)  It is a good dehydrating agent 4)  It is used in car batteries

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24 Properties of Bases Bases feel slippery Bases are electrolytes
Bases are corrosive, poisonous, and can cause severe burns (Lye = conc. NaOH) Bases turn litmus blue; Blue = Base Bases = pH greater than 7 Big in Base 6) Bases neutralize acids

25 Common Bases – Ref. L Ammonia NH3
1)  The most widely used base 2)  Used in household cleaning materials 3)  Used as fertilizer; adds nitrogen to soil Calcium hydroxide (caustic lime) Ca(OH)2 1)  Used  to make mortar and plaster 2)  Used to help neutralize acid soil Sodium hydroxide (Lye) NaOH 1)  One of the strongest bases 2)  Used in oven cleaners and drain cleaners

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27 Always Use Ref. Tables Acids ending = “- ic” Bases = Metal + hydroxide
(vinegar)

28 Reactions of Acid with metals
Use table J! Metals above H2 in table J react with acids by a single replacement reaction producing H2. 2 HCl + Zn  H2 + ZnCl2

29 Neutralization Reaction
Acids and bases react to neutralize each other, forming water and a salt: Acid + Base  Water + Salt HA + XOH  H2O + XA Double Replacement Reaction

30 Ma x Va = Mb x V b Titration
Is a process that uses a neutralization to determine the concentration of an acid or a base. Concentration in molarity is the amount of moles of solute per liter of solution. When the reaction of neutralization is 1:1 we use the following formula in a titration Ma x Va = Mb x V b

31 Vocabulary Standard solution : the solution of known molarity
Buret : instrument to measure exact volumes of liquids Erlenmeyer Flask Indicator : a substance that changes color in the presence of an acid or base. End point: when the amount of H+ = OH-

32 At the end point Ma x Va = Mb x V b

33 Acid – Base Titration Erlenmeyer flask
Two Burets with valves at bottom. Record vol. in mL (twice) Color indicator = phenolphthalein Acid H + Base OH - Erlenmeyer flask

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37 What is pH ? pH is the negative logarithm of the hydrogen ion concentration = pH = - log [H+] Remember that sometimes H+ is written H3O+, so pH = - log [H3O+] means the same thing.

38 pH Scale = log (base 10) scale
pH is.. Big in Base & Blue An increase of 1 in pH corresponds to a decrease of a factor of 10 in H+ concentration.

39 Typical pH Values of Common Materials
Battery Acid Stomach Acid Lemon Juice Vinegar, Soft Drinks Acidic Tomatoes Coffee / Tea Typical pH Values of Common Materials Milk Saliva Neutral Pure Water Blood Seawater Baking Soda Soap Basic Ammonia (NH3) Hair Remover Oven Cleaner / Drain Cleaner

40 More about pH Kw = dissociation constant for water = 10-14
1 x = [H+] x [OH-] = [ 10-7 ] x [ 10-7 ] A neutral solution has a pH of 7. [H+] = [OH-] = 1 x 10-7 M

41 pH and [H+] If pH is… [H+] = ?? pH = 8 _____ pH = 12 _____

42 Finding pH for a solution of a strong acid or strong base
For strong acid the concentration of the acid is the same as H+ For strong bases the concentration of the base is the same as OH-.

43 Find the pH for A) M HCl B) 0.01 M HBr C) M NaOH

44 Acid-Base Indicators A substance that have different colors at different pH.

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46 Always Use Ref. Tables (vinegar)

47 Bronsted Lowry definition
An ACID is a substance that donates H+ A BASE is a substance that ACCEPTS H+

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52 P 177 REVIEW BOOK 2 1 4 3 2 4 1

53 P 181 Review Book 4 1 2 )4 )3 4 1 2 3

54 P 185 answers 4 2 1 25 ml 3000ml 20mL 50mL 6M

55 P 178 rb answers 14. chlorate 15 a) hydrosulfuric acid
b) hydrobromic acid c) lithium hydroxide d) magnesium hydroxide 16. An electrolyte can also be a base or a salt. An indicator can be added to test if is an acid or a base.

56 Page 187 answers 4 1 3 2 2 Bromocresol green Bet 5.4 and 6 A blue
yellow 74) B 75) 1

57 Handout Answers 2 4 3 pH=6 Methyl orange/ Bromthymol blue
Bromocresol green


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