chapter 18
Download
Skip this Video
Download Presentation
Chapter 18

Loading in 2 Seconds...

play fullscreen
1 / 53

Chapter 18 - PowerPoint PPT Presentation


  • 77 Views
  • Uploaded on

Chapter 18. Acids and Bases Rainbow Connection #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. Properties of Acids. Have pH  0-6

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Chapter 18' - linda-welch


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
chapter 18

Chapter 18

Acids and Bases

Rainbow Connection

#2

ch 18 acids and bases
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
properties of acids
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
acid formulas memorize
Acid Formulas (memorize)
  • HCl ( Hydrochloric Acid)
  • HNO3 (nitric acid)
  • H2SO4 (sulfuric acid)
  • H2CO3 (carbonic acid)
  • HC2H3O2 (acetic acid)
  • H3PO4 (phosphoric acid)
properties of bases
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
acid base theories
Acid/ Base Theories
  • Definitions have changed over the years as new information has been found
  • Arrhenius Theory video
arrhenius theory 1887
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
slide10
Ex. HCl  H+(aq) + Cl-(aq)

ACID

NaOH  Na+(aq) + OH-(aq)

BASE

br nsted lowry theory 1923 video
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)
slide12
HCl + H2O  H3O+ + Cl-

Accepts proton (base)

Donates (loses) proton – (acid)

H3O+  hydronium ion (formed when H2O gains H+ ion)

slide13
NH3 + H2O  NH4+ + OH-

Accepts proton (base)

Donates (loses) proton – (acid)

Amphoteric – (H2O) acts as an acid or a base (depending on the situation)

conjugates
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
slide15
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
slide16
Ex.

HNO3 + NaOH  H2O + NaNO3

(H-OH)

Acid

Conjugate Base

Base

Conjugate acid

slide18
Ex.

KOH + HBr  KBr + H2O

Base

Conjugate Acid

Acid

Conjugate Base

neutralization reaction
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
slide21
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)
examples of neutralization reactions
Examples of Neutralization Reactions
  • Sodium hydroxide + hydrochloric acid  sodium chloride + water
  • NaOH + HCl  NaCl + H2O (H-OH)
slide23
Potassium hydroxide + sulfuric acid  water + potassium sulfate
  • KOH + H2SO4 

H- OH + K2SO4

2 KOH + H2SO4 2 H-OH + K2SO4

titration1
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 + .05 ml
definition
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
process
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)
calculations
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)

slide33
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 + 1 HCl  NaCl + H2O (H-OH)
  • So: 1 mole (base) = 1 mole (acid)
  • Therefore: MA VA = MBVB
problem
Problem
  • A titration of 15.00 ml of HCl, required 38.57 ml of a 0.152 M base NaOH. Calculate the molarity of the HCl (acid).
  • MA = ?
slide35
MA VA = MBVB
  • MA = M BVB
  • VA
  • MA = (.152M) (38.57 ml)
  • (15.00ml)
  • MA = .391 M
id a b ca cb
ID- A, B, CA, CB
  • CaCO3 + HCl  CaCl2 + H2CO3
  • KOH + H3PO4 K3PO4 + H2O
slide38
phosphoric acid + calcium hydroxide calcium phosphate + water
  • HBr + Al(OH)3
  • Sulfuric acid + potassium hydroxide 
indicators
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

needs of indicators
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
indicator examples
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)
ionization of h 2 o
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
ion product constant for water
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 10 -14
  • [H+] [OH-] = 1.0 x 10 -14
slide46
If [H+] = 1.5 x 10 -6 M, what is the [OH-] = ?
  • [H+] [OH-] = 1.0 x 10 -14
  • (1.5 x 10 -6) [OH-] = 1.0 x 10 -14
  • [OH-] = 1.0 x 10 -14
  • 1.5 x 10 -6
  • [OH- ] = 6.7 x 10-9 M
ph concept video
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+]

slide48
Ex. [H+] = 1.5 x 10-8

pH= ?

Graphing Calc.

(-) log 1.5 (2nd) EE -8

Regular calc.

1.5 EE -8 log +/- pH= 7.8

to go from ph to h concentration
To go from pH to [H+]concentration

3. [H+] = antilog (-pH)

Antilog = 10x key

slide50
pH= 3.5
  • [H+] = ?

[H+] = antilog (-pH)

[H+] = antilog (-3.5)

Graphing = 2nd log -3.5

Regular 3.5 +/- 2nd log

(to put in sci.not. Use 2nd #5)

[H+] = 3.2 x 10 -4 M

poh hydroxide power
pOH (hydroxide power)
  • pH + pOH =14
    • pH= 8
    • pOH = ?

8 + ? = 14 pOH= 6

  • pOH = - log [OH-]
  • [OH-] = antilog (-pOH)
slide52
[H+] = 3.5 x 10 -7 M, [OH-] = ?

pH = 8.95 , [H+] = ?

[OH-] = 5.65 x 10 -2 M, pOH = ?

pOH= 11.9, [H+] = ??

Formula 1

Formula 3

Formula 5

Formula 4, then 3 or

Formula 6, then 1

ad