1. Acids and Bases

2. Review -What is an ion? -What are the properties of an acid?
-What are some common acids?
-What are the properties of a base?
-What are some common bases?
-What does pH mean?

3. Acids -From latin word "acere" which means sour
-Sourness is the taste that detects acidity
-Many sour candies use citric acid

4. Bases -Another older word we use for some basic is alkali
-The word is derived from Arabic al qalīy
-meaning roasting which had to do with a process from making soap with lime
-It was known that they caused burns on skin when concentrated
-These substances also felt slippery

5. -It was also known that when acids and bases were mixed together, some kind of heat producing reaction would happen

6. -Pure Water -7

7. -Hydrochloric Acid (HCl)-0
-Sodium Hydroxide (NaOH)
-14

8. -Milk
-6.6
-Ammonia
-11
-Vinegar
-2.2
-Baking Soda
-8.3
Guess the pH

9. -Blueberries
-Butter
-Grapes

11. -Acids have always been studied
-In 1677 Antoine Lavoisier proposed that oxygen made an acid acidic
-derived the name oxygen from greek words meaning "acid former"
-In 1808 it was discovered that HCl contains only hydrogen and chlorine
-People discovered that hydrogen was the important factor in what made an acid

12. Conductivity of Water
-Ions are needed in a solution to conduct a current
-Pure water with no ions would theoretically not conduct electricity at all

13. Conductivity of Water
-However pure water does have a slight conductivity
-Svante Arrhenius had the theory that this was due to the presence of ions
-Where do the ions come from?

14. Self-Ionization of Water
H2O + H2O > H3O+ + OH−

15. Keq = [H30]+[OH]
[H20]2
At 25 °C Keq is equal to 1.0×10−14

16. -In this reaction at equilibrium the products are heavily favoured
-In 1884 the first modern definition of an acid and a base was given by Svante Arrhenius

17. According to Arrhenius...
-An acid is a substance that dissociates in water and increases [H3O+]
-A base is a substance the dissociates in water and increases [OH]

18. -According to Arrhenius, when we add an acid to water...

19. Some common acids
What do they all have in common?

20. According to Arrhenius, when a base is added to water...

21. Some common bases Sodium Hydroxide - NaOH Potassium Hydroxide - KOH
Ammonium Hydroxide - NH4OH
Calcium Hydroxide - Ca(OH)2
Magnesium Hydroxide - Mg(OH)2
Barium Hydroxide - Ba(OH)2
Aluminum Hydroxide - Al(OH)3
Zinc Hydroxide - Zn(OH)2
Lithium Hydroxide - LiOH

22. -BOTH H+ and OH- ions are ALWAYS PRESENT in any solution.
-A solution is acidic if the H+ are in excess.
-A solution is basic, if the OH- ions are in excess.

23. Arrhenius also said...
-All acids and bases react with each other in the same way
- acid + base = salt + water
- HCl + NaOH = NaCl + H20

24. Measuring Acidity and Alkalinity
-How do we measure how acidic or basic something is?
-We usually measure [H3O+]
-Math Review: What is a power?
-pH means the power of [H+]
-We use logarithms to measure pH
-logs are the opposite of exponents the same ways division is the opposite of multiplication

25. Logarithms - y=bx is the same as logby = x -In pH, b is always 10
-What is:
-log101 =
-log1010 =
-log10100 =
-log =

26. Logarithms -What is: -log100.1 = -log100.01 = -log100.001 =

27. pH
-this is defined as the negative logarithm of the hydrogen ion concentration
pH = - log [H+]
-Why are we using the negative logarithm?

28. Example
If an acid has an H+ concentration of M,
find the pH.

29. Solution -H+ = 0.0001M = 10-4 -log of 10-4 = -4
-pH = - log [ H+] = - log (10-4) = - (-4) = +4
-The purpose of the negative sign in the log definition is to give a positive pH value.

30. For each of the following [H+] , calculate the pH:
a) 3.28 x10-4
b) 9.43 x10-13
c) 2.71 x10-8
d) 1.00 x10-3
e) 1.00 x10-12

31. Finish the table H+ pH
pOH
OH-
1.0 x10-4
3.9
1.2
8.3x10-10

32. For each of the following pH values, calculate [H+]:
a) pH = 5
b) pH = 3
c) pH = 2.8
d) pH = 13.7
e) pH = 6.9

33. -If pH is based off [H+],
is there such a thing as pOH that is based off the concentration of [OH-]
-YES, THERE IS!!!!

34. Find pOH from the following [OH-]
-3 x10-3
-9 x10-6
-1 x10-11

35. -log (3 x10-3) = 2.52
-log (9 x10-6) = 5.05
-log (1 x10-11) = 11

36. Problems with the Arrhenius idea
-Certain substance produce basic solutions and react with acids but don't contain hydroxide ions
-An example is ammonia(NH3)

37. New Theory
-In 1923, Johannes Nicolaus Brønsted and Martin Lowry created new definitions for an acid and a base
- Brønsted–Lowry acids are hydrogen ion donors
- Brønsted–Lowry bases are hydrogen ion acceptors
-We call this the Brønsted–Lowry acid–base definition

38. - An acid can donate a hydrogen ion (a proton) to another substance while a base can accept a proton from another substance
Acid
Base
Donates hydrogen ions
Accepts hydrogen ions.
HCl+
HOH →
H3O+ + Cl-
HOH+
NH3→
NH4+ + OH-

39. -The ion or molecule remaining after the acid has lost a proton is known as that acid's conjugate base
-The species created when the base accepts the proton is known as the conjugate acid
-acid+ + base- conjugate base- + conjugate acid+
- this reaction can proceed in either forward or backward direction; in each case, the acid donates a proton to the base

42. Relative Strengths of Acids and Bases
-Strong acids are better H+ ion donors than weak acids
-Strong bases are better H+ acceptors than weak bases

43. -HCl is a strong acid and HF is a weak acid
-In a dilute solution the ionization of HCl is virtually 100%
-Essentially all the HCl molecules react with water

44. -With HF the reverse of the ionization is significant
-the F- readily accepts the H+ from the hydronium
-Hydrofluoric acid is mainly unionized in dilute solution

45. -Strong acids have weaker conjugate bases
-Weaker acids have stronger conjugate bases

46. http://www. sparknotes

47. Bases: 3 ways of OH- formation
-Neutral base extraction of H+ from H2O
NH3 (aq) + H2O(l) ⇔ NH4+ (aq) + OH- (aq)
-Anionic base extraction of H+ from H2O
CO32- (aq) + H2O(l) ⇔ HCO3- (aq)+ OH-
-Metal hydroxide dissociation to M+ and OH-
NaOH (aq) → Na+ (aq) + OH- (aq)

48. Ka for the following equation
HA(aq) + H2O(l) H3O+(aq) + A–(aq)