Date: October 19, 2015
Aim #17: How are acids and bases different?
Do Now: Warm-Up Notebook
Date
10/19
Title of Activity
Properties of Water
Page #
32
HW:
1)Worksheet- Properties of Water Due Tuesday
2)Guided Reading 2-2 Due Thursday
3)Quiz (Inorganic Chemistry)- Wednesday 10/21 & Thursday
10/22 (day of double period)
Aim #17- How are acids and
bases different?
What does the pH scale measure?
• Measures the hydrogen ion (H+) concentration of a solution.
Acid pH 0-6 Neutral pH 7 Base pH 8-14
What is an acidic solution?
• Any compound that produces
H+ ions in solution
• Consists of molecules that
contain H covalently bonded to
another group of atoms
• When this molecule is put in
water, it will dissolve and the H
breaks loose as an H+
Example: HCl (hydrochloric acid)
• HCl without water is a gas, but
when dissolved in water the H
becomes an H+ and Cl becomes
a Cl-
What is a basic solution?
• Any compound that produces
hydroxide ions (OH-) when
dissolved in water
• Example: NaOH (Sodium
Hydroxide)
• separates when dissolved in water,
the Na becomes Na+ and the OH
becomes OH-
What is a neutral solution?
• A solution with a pH of 7
• Contains equal concentrations of
hydrogen ions (H+) and hydroxide
ions (OH-)
• Example: pure water
*distilled water is considered to
be pure water
Concept Check: Let’s Review Acids and Bases
by completing the chart below!
ACIDS
BASES
H+
concentratio
n (high/low)
High
Low
pH value
Lower than 7
Higher than 7
Examples
Acid rain, vinegar, Seawater, blood,
lemons
bleach
Neutral
Equal concentrations of
H+ and OH-
7
Distilled water
What is neutralization?
• When an acid and base are mixed, the H+ from the acid combines
with the OH- from the base
• The positive and negative cancels each other out and the substance
becomes neutral
• What happens when H+ and OH- join?
•
water is formed (H2O)!!
How do buffers work?
• A buffer is a solution that can
resist pH change upon the
addition of an acidic or basic
components. It is able to
neutralize small amounts of
added acid or base, thus
maintaining the pH of the
solution relatively stable.
• Buffers are found in our body to
help neutralize the blood if
excess H+ (hydrogen ions) or
OH- (hydroxide ions) are present
• Acidosis: pH drops too low and
blood is too acidic
• Alkalosis: pH is too high
• Common buffers: HCO3(bicarbonate ion) and H2CO3
(carbonic acid)
How can we measure the pH of a solution
using indicators?
• An indicator is a substance that
changes color when pH goes
above or below a certain value
• Used to see if something is
acidic, basic or neutral
• Litmus paper: red, blue or white
• pH paper
• Phenolphthalein: changes from
colorless to pink in a moderately
basic solution (pH above 10)
BrainPop
• http://www.brainpop.com/scien
ce/matterandchemistry/phscale/
• http://www.brainpop.com/scien
ce/matterandchemistry/acidsan
dbases/
In Closure….let’s bring it all together!
As the concentration of H+ increases,
the solution becomes more acidic,
and the pH decreases.
As the concentration of H+ decreases,
the solution becomes more basic,
and the pH increases.