1. Acids and Bases Rainbow Connection #2
Chapter 18
Acids and Bases
Rainbow Connection #2

2. Ch. 18- Acids and Bases
Acids and bases have a central role in chemistry
They affect our daily life
Uses: manufacturing processes, environmental issues, functioning of our bodies
Acid/ Base Video

5. Properties of Acids Have pH  0-6 Tart or sour taste
Will conduct electricity
Cause indicators to change color (turns blue litmus red)
Reacts w/ metals (Mg,Zn) to form H2 gas
Neutralize w/ a base forms a salt and H20
Ex. Citrus foods, tomatoes, vinegar

6. Acid Formulas (memorize)
HCl ( Hydrochloric Acid)
HNO3 (nitric acid)
H2SO4 (sulfuric acid)
H2CO3 (carbonic acid)
HC2H3O2 (acetic acid)
H3PO4 (phosphoric acid)

7. Properties of Bases Also known as alkaline pH  8-14
Have a bitter taste, slippery feel
Causes indicators to change color (turns red litmus blue)
Conducts electricity
Reacts w/ acid to neutralize  form a salt and H2O
Ex. Cleaning products, soap, baking soda

8. Acid/ Base Theories
Definitions have changed over the years as new information has been found
Arrhenius Theory video

9. Arrhenius Theory (1887) Applies to a H2O solution
Svante Arrhenius (Swedish) saw that not only do acids/ bases conduct electricity, they ionize (or release charged particles) when dissolved in water
Theory:
Acids- substance that ionize & produced (H+) hydrogen ions in H2O
Bases- ionize to produce (OH-) hydroxide ions in H2O

10. Ex. HCl  H+(aq) + Cl-(aq)
ACID
NaOH  Na+(aq) + OH-(aq)
BASE

11. Brønsted- Lowry Theory (1923) (video)
Working independently of each other, Johannes Brønsted (Danish) and Thomas Lowry (English) defined a theory that can be used w/ all solvents not just H2O (they found that substance lost or gained protons)
Acid- in a chemical reaction, this is the substance that loses or donates a proton (H+ ion)
Base- substance that accepts or gains a proton (H+ ion = proton)

12. HCl + H2O  H3O+ + Cl- Accepts proton (base)
Donates (loses) proton – (acid)
H3O+  hydronium ion (formed when H2O gains H+ ion)

13. NH3 + H2O  NH4+ + OH- Accepts proton (base)
Donates (loses) proton – (acid)
Amphoteric – (H2O) acts as an acid or a base (depending on the situation)

14. Conjugates
The particles that are formed as products can react again (reversible reaction), they behave like acids and bases (we call these conjugates)
Conjugate video

15. Conjugate Acid - Particle that forms after the base accepts a proton (H+) from the acid
Conjugate Base – particle that remains after a proton (H+) has been released by the acid

16. Ex. HNO3 + NaOH  H2O + NaNO3 (H-OH) Acid Conjugate Base Base
Conjugate acid

17. Disappearing ink

18. Ex.
KOH HBr  KBr + H2O
Base
Conjugate Acid
Acid
Conjugate Base

20. Neutralization Reaction
Occurs when an acid and a base react and there is a complete removal of all of the H+ and OH- ions
Water will be formed w/ a salt in this double displacement reaction
The solution will be neutral in pH
Important in: neutralization of soil, antacids

21. Salt
Crystalline compound composed of the negative (non-metal) ion of the acid and the positive (metallic ) ion of the base
Salt examples: CaSO4 (plaster board), NaCl, KCl, (NH4)2SO4 (fertilizer)

22. Examples of Neutralization Reactions
Sodium hydroxide + hydrochloric acid  sodium chloride + water
NaOH + HCl  NaCl + H2O (H-OH)

23. Potassium hydroxide + sulfuric acid  water + potassium sulfate
KOH H2SO4 
H- OH K2SO4
2 KOH H2SO4  2 H-OH K2SO4

24. Aluminum hydroxide + acetic acid 

25. Titration

26. Titration
Used for a convenient method to determine the concentration or molarity of an acid or base
Uses 2 burets (long glass tubes used to measure volume)- Buret ml

27. Definition
Analytical method in which a standard solution is used to determine the concentration of another solution
Standard solution- one in which the concentration is known

28. Process
Using a given amount of acid in a flask, add phenolphthalein and titrate to the end point with the base (making sure to mark down all the volumes)
The whole reaction is a neutralization reaction
Use an indicator to see the endpoint in which complete neutralization occurs (wait for phenolphthalein stays light pink for 30 sec)

30. Past endpoint
Endpoint

31. Titration Process

32. Calculations Reminder: M= moles liters So: Base (titrated soln) 
Moles (base) = volume (base) x Molarity (base)
Acid (standard soln) 
Moles (acid) = volume (acid) x Molarity (acid)

33. Look at balanced equation and find the moles of the standard and the moles of the titrated unknown (look at coefficients)
Most times it is a 1:1 ratio
1 NaOH HCl  NaCl + H2O (H-OH)
So: 1 mole (base) = 1 mole (acid)
Therefore: MA VA = MBVB

34. Problem
A titration of ml of HCl, required ml of a M base NaOH. Calculate the molarity of the HCl (acid).
MA = ?

35. MA VA = MBVB
MA = M BVB VA
MA = (.152M) (38.57 ml)
(15.00ml)
MA = .391 M

36. Titration Calculation

37. ID- A, B, CA, CB
CaCO3 + HCl  CaCl2 + H2CO3
KOH + H3PO4  K3PO4 + H2O

38. phosphoric acid + calcium hydroxide calcium phosphate + water
HBr + Al(OH)3
Sulfuric acid + potassium hydroxide 

39. Indicators Used to find out if things are acidic or basic
Def: weak organic acids or bases whose colors differ from the colors of their conjugate acids or bases
base
acid

41. Needs of Indicators Solution being tested needs to be colorless
You need to be able to distinguish the color change
Need several indicators to cover entire pH range (0-14)
Liquid solution

42. Indicator Examples
Litmus  red turns blue = base, blue turns red = acid
Phenolphthalein hot pink > pH 10
Bromothymol blue  blue= base (8), Green= neutral, yellow = acid (6)
Universal Indicator  Rainbow (all pH’s 4-10)
(bromothymol blues)

43. How Chemists use Indicators

44. Ionization of H2O
Pure water can self ionize, it also acts as an acid or a base (amphoteric)
So: H2O(aq)  H+(aq) + OH- (aq)
Experiments have shown that the concentration of [H+] = 1 X 10 –7M and [OH-] = 1 x 10 –7 M in pure water
[ ] means concentration

45. Ion Product Constant for water
Equilibrium expression from the multiplication of the concentrations of the products
[H+] [OH-] =?
(1 x 10 –7)(1 x 10 –7) = 1.0 x
[H+] [OH-] = 1.0 x

46. If [H+] = 1.5 x 10 -6 M, what is the [OH-] = ?
[H+] [OH-] = 1.0 x
(1.5 x 10 -6) [OH-] = 1.0 x
[OH-] = 1.0 x
1.5 x 10 -6
[OH- ] = 6.7 x 10-9 M

47. pH Concept (video)
Acidity scale developed by Soren Sorenson base on the “power of the hydrogen”
pH – measure of the hydrogen ion concentration of the solution
Equal to the negative logarithm of the hydrogen ion concentration
2. pH = - log [H+]

48. Ex. [H+] = 1.5 x 10-8
pH= ?
Graphing Calc.
(-) log (2nd) EE -8
Regular calc.
1.5 EE log +/ pH= 7.8

49. To go from pH to [H+]concentration
3. [H+] = antilog (-pH)
Antilog = 10x key

50. pH= 3.5
[H+] = ?
[H+] = antilog (-pH)
[H+] = antilog (-3.5)
Graphing = 2nd log
Regular / nd log
(to put in sci.not. Use 2nd #5)
[H+] = 3.2 x M

51. pOH (hydroxide power) pH + pOH =14 pOH = - log [OH-]
[OH-] = antilog (-pOH)

52. [H+] = 3.5 x M, [OH-] = ?
pH = , [H+] = ?
[OH-] = x M, pOH = ?
pOH= 11.9, [H+] = ??
Formula 1
Formula 3
Formula 5
Formula 4, then 3 or
Formula 6, then 1

53. Rosengarten acid and base video