1. The Acid Test
Acids, Bases and pH

2. 2. Describe the pH Scale
The next few slides will illustrate this point. Be sure to write small and get it all!

3. The pH scale ranges from 0 to 14.
Range of pH scale
The pH scale ranges from 0 to 14.
There are no units of measure for pH *

4. pH Range [H+]>[OH-] [H+] = [OH-] [OH-]>[H+]
Neutral
[H+]>[OH-] [H+] = [OH-] [OH-]>[H+]
Acidic
Basic

5. Learning Check pH7 Identify each solution as
1. acidic basic 3. neutral
A. _____ HCl with a pH = 1.5
B. _____ Pancreatic fluid pH = 8
C. _____ Sprite soft drink pH = 3.0
D. _____ pH = 7.0
E. _____ pH = 3
F. _____ pH = 12

6. Solution pH7 Identify each solution as 1. acidic 2. basic 3. neutral
A. _1__ HCl with a pH = 1.5
B. _2__ Pancreatic fluid pH = 8
C. _1__ Sprite soft drink pH = 3.0
D. _3__ pH = 7.0
E. _1__ pH = 3
F. _2__ pH = 12

7. 3. What is a hydronium ion? . . . . . . . . H H H . . . . . . . .
Occasionally, in water, a H+ is transferred between H2O molecules
H:O: :O:H H:O:H :O:H-
H H H
water molecules hydronium hydroxide ion (+) ion (-)

8. 4. How can the pH of a solution be determined?
There will be several slides showing various ways to measure pH. Be sure to get them all!

9. Litmus paper Litmus paper cannot tell you the exact pH of a substance.
It can only tell you if it is an acid or a base
Blue litmus turns pink in the presence of an acid
Red litmus turns blue in the presence of a base*

10. pH paper pH paper can tell you approximate pH values.
By placing one end of the pH paper in the solution it will turn a color which can be matched to the color code key. *

11. Indicators Indicators:
Weak organic acids and bases whose colors differ from the colors of their conjugate acids or bases.
The color is best viewed from above against a white background

12. Table of Indicators Acid / Base Indicators Indicator Lower Color
     
Acid / Base Indicators
Indicator
Lower Color
pH Range
Upper Color
methyl violet
yellow-green
violet
methyl orange
red
yellow
congo red
blue
bromocresol green
methyl red
bromocresol purple
bromothymol blue
phenol red
red-violet
cresol red
phenolphthalein
colorless
dark pink
Phenolphthalein is a common indicator to use in neutralization titrations. The solution is considered neutral when the solution holds a very faint pink color for half a minute or more.
alizarin yellow R
dark orange

13. pH Meter
The most precise and usually more accurate way to measure pH is using a pH meter which directly measures the amount of [H3O+] in the solution
Uses an electrode which specifically measures the pH of the solution.
This is a larger model. Some are small enough to be hand-held.*

14. 5. What are the properties of an acid?
Acids
Taste sour
Donate a H+
pH less than 7
Turn litmus paper red
Turn bromothymol blue to yellow
Turn phenolphthalein colorless
Neutralize bases

15. 6. What are the properties of bases?
Taste bitter
Usually ends in -OH
pH greater than 7
Turn litmus paper blue
Turn bromothymol blue to blue
Turn phenolphthalein pink
Feel slippery to touch
Neutralize acids*

16. Learning Check AB2
Identify each as characteristic of an A) acid or B) base
____ 1. Sour taste
____ 2. Produces OH- in aqueous solutions
____ 3. Chalky taste
____ 4. Is an electrolyte
____ 5. Produces H+ in aqueous solutions*

17. Solution AB2
Identify each as a characteristic of an A) acid or B) base
_A_ 1. Sour taste
_B_ 2. Produces OH- in aqueous solutions
_B_ 3. Chalky taste
A, B 4. Is an electrolyte
_A_ 5. Produces H+ in aqueous solutions*

18. Learning Check AB1
Describe the solution in each of the following as: 1) acid 2) base or 3)neutral.
A. ___soda
B. ___soap
C. ___coffee
D. ___ wine
E. ___ water
F. ___ grapefruit*

19. Solution AB1 Describe each solution as: 1) acid 2) base or 3) neutral.
A. _1_ soda
B. _2_ soap
C. _1_ coffee
D. _1_ wine
E. _3_ water
F. _1_ grapefruit*

20. 7. What compounds are formed when an acid reacts with a base?
When acid and bases with equal amounts of hydrogen ion H+ and hydroxide ions OH- are mixed, the resulting solution is neutral.
NaOH (aq) HCl(aq) NaCl + H2O
base acid salt water
Ca(OH) HCl CaCl H2O
base acid salt water*

21. Learning Check N2
Select the correct group of coefficients for the following neutralization equations
A. __ HCl + __ Al(OH) __AlCl3 + __ H2O
1) 1, 3, 3, 1 2) 3, 1, 1, ) 3, 1, 1 3
B.__ Ba(OH)2 + __H3PO __Ba3(PO4)2 + __ H2O
1) 3, 2, 2, 2 2) 3, 3, 1, ) 2, 3, 1, 6

22. Solution N2 A. 3HCl + 1Al(OH)3 1AlCl3 + 3H2O
B. 3Ba(OH) H3PO Ba3(PO4) H2O*

23. A practical use of the neutralization process
8. Antacids
A practical use of the neutralization process

24. Antacids Used to neutralize stomach acid (HCl)
Many contain one or more weak bases
Alka-Seltzer: NaHCO3, citric acid, and aspirin
Di-gel: CaCO3 and Mg(OH)2
Gelusil: Al(OH)3 and Mg(OH)2
Maalox: Al(OH)3 and Mg(OH)2
Mylanta: Al(OH)3 and Mg(OH)2*

25. More Antacids Milk of Magnesia: Mg(OH)2 Rolaids: AlNa(OH)2CO3
aluminum sodium dihydroxy carbonate
Tums: CaCO3
Tempo: CaCO3, Al(OH)3, Mg(OH)2*

26. Which solution is more acidic the one with a pH of 2 or the one with a pH of 6?
To answer this we are going to look at concentration and its effects on the environment.

27. pH measures the concentration of hydrogen ion [H+] in a solution
So every time you increase one number on the pH scale the acidity (or alkalinity) increases by a power of 10!
The concentration of pH = 2 solution is 4 pH values from a pH = 6 solution or
The pH = 2 solution is 10,000 times more acidic than the pH = 6 solution

28. What does this mean for the environment?
An in-depth look at acid rain

29. Acid Rain Formation of acid rain:
1. Emission of sulfur and nitrogen oxides from the burning of fuels especially coal with high S content, power stations, oil refineries, vehicles as well as bacterial decomposition, and lighting hitting N2
SO million tons in 1980
NO and NO2 22 million tons in 1980
Mt. St Helens (1980) 400,000 tons SO2*

30. Acid Rain
2. Reactions in the atmosphere form SO3
2SO2 + O2  2 SO3*

31. Acid Rain 3. Reactions with atmosphere water form acids
SO3 + H2O  H2SO4 sulfuric acid
NO + H2O  HNO2 nitrous acid
HNO2 + H2O  HNO3 nitric acid*

32. Acid Rain 4. Effects of Acid Rain
Decline in fish populations in rivers and lasts due to toxic effect of Al leached from soil by acid rain
Extensive fish kills in spring from runoff due to accumulation of large amounts of acid on the snow
Dissolves minerals Mg, Ca, and K from the soil and waxy coatings that protect leaves from bacteria
Corrodes metals, textiles, paper and leather*

33. Sources of Acid Rain Power stations Oil refineries
Coal with high S content
Car and truck emissions
Bacterial decomposition, and lighting hitting N2*