pH
Order the following substances in order
Water is one of the most important inorganic substances of increasing acidity: human blood,
in living organisms.
acid rain, bleach, seawater, stomach
acid.
Sometime water molecules will break apart to form ions.
This is called dissociation.
1. _bleach___(least acidic / most basic)
2. _ seawater__
3. _ human blood __
Ion- a positively or negatively charged atom (set of atoms)
due to loss or gain of electrons
4. _acid rain___
5. _stomach acid__(most acidic)
About 1 water molecule in 550 million splits in this way.
Because the number of positive H+ ions is equal to the
number of negative OH- ions, water is neutral.
Acid, Base, or Neutral? Strong or weak?
pH 7:___N__ pH 13.5:__SB____ pH 8:__WB___ pH 2:__SA____
The pH scale- measures the concentration of hydrogen ions
[H+] in a particular solution.
•
•
•
•
•
Measured 0-14
Each step represents a factor of ten (10).
7 is neutral (like water)
Lower than 7 becomes more acidic
Higher than 7 becomes more basic
Personal notes, summary of lesson, questions:
Which one is more acidic?(circle one)
pH of 2
-or-
pH of 4
How many times more?__100x_____
Which one is more basic? (circle one) Tomato juice
-or-
Soap
How many times more?__106 or 1,000,000x
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ACID- compound that forms H+ ions in solution
ACIDS
BASES
Solutions have a pH
Less than7
Solutions have a pH
greater than__ 7
Taste sour
Taste bitter
Can corrode metals
Can denature proteins (feel
"slippery")
In solution: [H+] __>___
[OH-]
In solution: [H+] __<_____
[OH-]
BASE- compounds that forms OH- ions in solution
• Study the reaction below. Is this substance an ACID or BASE?
(circle)
Dissociation In Water
HCl
Hydrogen Chloride
Hydrochloric acid

H+
Hydrogen ion
(Proton)
+
ClChloride ion
ACIDIC
• Study the reaction below. Is this substance an ACID or BASE?
(Circle)
Dissociation In Water
NaOH
Sodium Hydroxide

Na+
Sodium ion
Personal notes, summary of lesson, questions:
+
H+
H+
H+
OHhydroxide ion
OH-
NEUTRAL
H+ OHH+
OH- H+
OH-
BASIC
OHH+
OHOH-
Range of pH __
0 – 6.9_______
Range of pH
___7___________
Range of pH __
7.1 -14_________
[H+] _>___ [OH-]
in this type of
solution.
[H+] __=__ [OH-]
in this type of
solution.
[H+] _<____ [OH-]
in this type of
solution.
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BUFFERS
Controlling pH is important for maintaining homeostasis in
cells. The pH of most cells in the human body must be kept
between ___6.5_____ and ___7.5____.
Buffers- Weak acids or bases that react with strong acids or
bases to prevent sharp, sudden changes of pH.
Example: Sudden pH changes in blood are prevented by
buffers such as bicarbonate and phosphate ions.
Personal notes, summary of lesson, questions:
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