pH
https://www.youtube.com/watch?v=Xeuyc55LqiY
Order the following substances in order
Water is one of the most important inorganic substances of increasing acidity: human blood,
acid rain, bleach, seawater, stomach
in living organisms.
acid.
Sometime water molecules will break apart to form ions.
1. _____________
Ion- a positively or negatively charged atom (set of atoms)
due to loss or gain of electrons
2. _____________
3. _____________
4. _____________
5. _____________
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:________ pH 13.5:________ pH 8:_________ pH 2:________
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?___________
Which one is more basic? (circle one) Tomato juice
How many times more?________
-or-
Soap
ACID- compound that forms H+ ions in solution
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

H+
Hydrogen ion
(Proton)
+
ClChloride ion
ACIDS
BASES
Solutions have a pH
_________7
Solutions have a pH
_________ 7
Taste sour
Taste bitter
Can corrode metals
Can denature proteins (feel
"slippery")
In solution: [H+] ______
[OH-]
In solution: [H+] _______
[OH-]
ACIDIC
NEUTRAL
Range of pH
______________
Range of pH
______________
BASIC
• Study the reaction below. Is this substance an ACID or BASE?
(Circle)
Dissociation In Water
NaOH
Sodium Hydroxide

Na+
Sodium ion
+
OHhydroxide ion
Range of pH
______________
[H+] _______
[H+] _______
[H+] ______ [OH-]
[OH-] in this type of [OH-] in this type of in this type of
solution.
solution.
solution.
Personal notes, summary of lesson, questions:
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.
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