Upload
helen-greene
View
238
Download
0
Tags:
Embed Size (px)
Citation preview
Acid-Base Theory
Ms. Murray
Let’s start with the theorists!
Lowry Picture Credit: http://www.geocities.com/bioelectrochemistry/lowry.htmBronsted Picture Credit:http://www.geocities.com/bioelectrochemistry/bronsted.htm
Lewis Picture Credit:
http://www.albion.edu/chemistry/CH121/LewisRules.htm
How should we define acids and
bases?
Arrhenius Picture Credit:http://scienceworld.wolfram.com/biography/Arrhenius.html
Arrhenius Model
1884 Acid – a substance that produces H+ ions
(protons) when dissolved in water Sour taste Low pH Turns litmus paper red
Base – a substance that produces OH- ions when dissolved in water Bitter taste Slippery feel High pH Turns litmus paper blue
Arrhenius Picture Credit:http://scienceworld.wolfram.com/biography/Arrhenius.html
Litmus Picture Credit:
http://oldwww.mtlsd.org/senior/science/JPtachcinski/Lab_Proc/Basic%20Science%20Lab%20Techniques.htm
Bronsted-Lowry Model
1923
Acids – proton (H+) donors
Bases – proton acceptors
BronstedLowry
Lowry Picture Credit: http://www.geocities.com/bioelectrochemistry/lowry.htmBronsted Picture Credit:http://www.geocities.com/bioelectrochemistry/bronsted.htm
Painting by E
llen Bronsted
Picture Credit: http://www.geocities.com/bioelectrochemistry/bronsted.htm
Painting by Bronsted (1923)
Lewis Model
Early 1920s
Acid – electron-pair acceptor
Base – electron-pair donor
Lewis Picture Credit:http://www.albion.edu/chemistry/CH121/LewisRules.htm
How do we measure how acidic or basic a compound is?
We measure its…
What is pH?
pH is a number that denotes the hydrogen (hydronium) ion concentration
pOH is a number that denotes hydroxide ion concentration
pH + pOH = 14
If we’re talking about hydrogen ions and hydroxide ions, which theorist should we be thinking about?
Picture Credit:http://scienceworld.wolfram.com/biography/Arrhenius.html
pH Scale
Scale from 1-14
Indicates the H+ concentration of a solution in Moles/L
pH = -log [H+]
http
://staff.jccc.n
et/P
DE
CE
LL
/che
mistry/p
hsca
le.h
tml
pH = -log[H+]
An example:
Given that [H+] = 1.0 x 10^(-7) M, find pH
pH = - log (1.0 x 10^(-7)) = -(-7.00) = 7.00*
*the number of decimal places here = the number of significant figures in the original number
Another example:
pH = -log[H+]
Given a pH of 6.00, calculate [H+] M
[H+] = 10^(-pH)
[H+] =10^(-6.00)
[H+] = 1.0 x 10^(-6.0) M
pH In Your World
The Good - Hydrangea
Picture Credit: http://www.flickr.com/photos/mshades/168884681/
Acceptable Use Policy: http://creativecommons.org/licenses/by/2.0/
Picture Credits: http://www.flickr.com/photos/cvalentine/439024324/Acceptable use policy: http://creativecommons.org/licenses/by-nc-nd/2.0/
Picture Credits: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AcidRain.html
1908 1968
The Bad
A castle in Westphalia, Germany. Built in 1702
Picture Credit: http://www.waterencyclopedia.com/A-Bi/Acid-Rain.html
The Really Ugly!
“And You Will Know Us by The Trail of Dead Fish” - ldandersen
Picture Credit: http://www.flickr.com/photos/ldandersen/181358675/
Acceptable Use Policy: http://creativecommons.org/licenses/by-nc/2.0/Salton Sea
Acid Rain
Damage
Picture Credit: http://www.eco-systems.org/air_pollution_and_dying_forests.htm
-Shenandoah National Park (1997)
-- Photo by Bob Winterbottom