Compounds are classified in
different ways
Chapter 5
SCIENCE 10
Chapter 5
Page 218-253
1
5.1 Acids and Bases
Notes, CYU (odds), RCs, WBook
5
Lab 5.2 C and 5.2 Quiz
2
Labs 5.1A and 5.1B
6
5.3 Organic Compounds
3
5.1 Quiz
7
Lab 5.3A and 5.3C
4
5.2 Salts
8
Chapter Test
To be completed in class only
In class
Notes, CYU (odds), RCs, WBook
To be completed in class only
Notes, CYU (odds), RCs, WBook
To be completed in class only
Class routine
Get organized!!
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•
•
•
20 minutes PowerPoint Lecture
15 Minutes Workbook
10 minutes Demo
Remainder - Lab Time (6 labs)
At Home – Handed in on test day
Get prepared!!
•
Assignment (all 1 package):
•
•
Make Notes for each chapter using
the headings found throughout the
chapter as your section titles
Reading Checks:
•
•
Check Your Understanding
•
•
Page 225,227,228,238,247
Page 233, 243, 251 (odd #s)
Understanding Key Ideas
•
Page 253 #16-23
Acids and Bases
You are familiar with them!
ACIDS
BASES
Stomach acid
Lemons
Grapes
Tomatoes
Vitamin C
Acid Rain
Eggs
Baking Soda
Soap
Bleach
Oven cleaner
Lime *not the fruit!
5.1 Acids and Bases
General properties
General formulas
•
•
•
Acids usually start with H
(hydrogen) on the left of the
formula. Ex. HCl
Bases usually have OH (hydroxide)
on the right. Ex. NaOH
Water is neutral
•
Bases have a pH
above 7.
Water is neutral at
pH 7.
H2O has 1 H and 1 OH !!!
Acids have a pH
below 7.
pH scale
Measures how acidic or basic a solution is
One unit of change represents a
10x (times) change in degree of
acidity or basicity
•
•
•
pH4 is 100x (2 steps=10 x 10) more
acidic than pH6
pH12 is 1,000,000x (6steps) more
basic than pH6
A small change in pH is a huge
change in acidity or basicity
pH actually means
proportion or
power of
Hydrogen H+ or
the concentration
of H+ ions
A theoretical pOH
scale would be the
opposite of pH.
pH indicators will
change colour in
the presence of
acid and bases.
Acids – pH below 7
Sour, tangy – strong acids are corrosive
Acids release H+ ions when dissolved in Water
• (aq) refers to Aqueous or “dissolved in H2O”
Can be named by chemical name:
HCl is Hydrogen Chloride
Can be named differently if shown with (aq)
• Ends in “-ic acid”
• HCl (aq) is Hydrochloric Acid
Acids that contain oxygen
-ic vs. -ous
Names that begin with Hydrogen and end with
–ate
•
•
H2CO3 – H2CO3 (aq)
Hydrogen carbonate – Carbonic acid
Names that begin with Hydrogen and end with
-ite
•
•
H2SO3 – H2SO3 (aq)
Hydrogen sulfite – Sulfurous acid
Bases – pH above 7
Bitter-tasting, slippery feel – strong reactive bases are caustic
Bases release OH‾ (hydroxide) ions when
dissolved in H2O
• A basic solution is also said to be Alkaline
• Chemical name ends with hydroxide
•
•
NaOH – sodium hydroxide
•
NaOH
Common names vary
Acids and Bases: chemical opposites
When an acid is mixed with a base, the solutions can neutralize each other.
If the concentration of
H+ is balanced with
the concentration of
OH‾ the solution is
neutral
•
•
Acid has more H+
Base has more OH-
pH indicators
An indicator changes colour depending on the pH.
Some common indicators include:
•
Litmus paper (BAR = Blue +
Acid turns red)
•
Phenolphthalein
•
Bromothymol blue
•
Indigo carmine
•
Methyl orange,
•
Methyl red
Some household items are indicators
Red Cabbage – Lab 5.1A (page 221)
Modified Lab:
1. Create a pH number
scale (#6)
2. Create an indicator
chart for Red
Cabbage indicator.
3. Tape the indicator
paper to the chart for
6+ samples
4. I notice, I Wonder
x3each
5. Name Date & Hand in
Red Cabbage Indicator
Pigment responsible: anthocyanin
The cabbage is actually PURPLE.
•
•
•
Turns GREEN in something basic
Turns RED in something acidic
Estimate the intensity of the change for your
chart… more intense red is more acidic…
Lab 5.1B Page 230
Handing in the following on a sheet of paper
1.
2.
3.
4.
5.
Question
Data Table
Analyze questions *full sentence response
Conclude and apply *full sentence response
Name Date
Lab 5.2C Page 241
Handing in the following on a sheet of paper
1.
2.
3.
4.
5.
Question
Data Table
Analyze *full sentence responses
Conclude and Apply *full sentence responses
Name Date
5.1 Acids and Bases
• Many familiar compounds are acids or bases.
 Classification as acids or bases is based on chemical composition.
• Acids and bases can be very dangerous.
 Both can be very corrosive.
 NEVER try to identify an acid or base by taste or touch!
• The strength of acids and bases in measured on the pH scale.
 pH below 7 = acidic, pH above 7 = basic, pH 7 = neutral
 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Acids
Neutral
Bases
 Each decrease of 1 on the pH scale indicates 10× more acidic
 For example, pH 4 is 10 times more acidic than pH 5.
 pH 3 is 1000 times more acidic than pH 6.
See pages 220 - 222
(c) McGraw Hill Ryerson 2007
pH Indicators
• The pH of acids and bases cannot be determined by sight.
 Instead, pH is measured by other chemicals called indicators
or by a pH meter that measures the electrical conductivity of the solution.
• pH indicators change colour based on the solution they are placed in.
 Litmus is the most common indicator, and is used on litmus paper.
 Two colours of litmus paper: Blue = basic and Red = acidic.
Litmus paper
 Blue = pH above 7, Red = pH below 7.
 Universal indicator contains many indicators that turn different colours at different pH
values (can be in liquid form, or on paper strips like litmus).
 A pH meter uses electrical probes to measure how solutions conduct electricity.
 Indicators change colour at different pH values, so different indicators are used to
identify different pH values.
 Bromothymol blue for pH 6 – 7.6, phenolphthalein for pH 8.2 – 10.
 Many natural sources, such as beets and cabbage,
are also indicators.
See pages 223 - 224
(c) McGraw Hill Ryerson 2007
Acids
• If you know a compound’s chemical formula, you may be able to
identify whether it as an acid.
 Acids often behave like acids only when dissolved in water.
 Therefore, acids often are written with symbol (aq) = aqueous = water.
• The chemical formula of an acid usually starts with hydrogen (H).
 Acids with a carbon usually have the C written first.
 HCl(aq) = hydrochloric acid, HNO3(aq) = nitric acid, CH3COOH(aq) = acetic acid
• Naming acids
 Hydrogen + …-ide = hydro…ic acid
 HF(aq) = hydrogen fluoride = hydrofluoric acid
 Hydrogen + …-ate = …ic acid
 H2CO3(aq) = hydrogen carbonate = carbonic acid
 Hydrogen + …-ite = …ous acid
 H2SO3(aq) = hydrogen sulphite = sulphurous acid
Sulfuric
acid is
used in
batteries.
See pages 225 - 226
(c) McGraw Hill Ryerson 2007
Bases
• If you know a compound’s chemical formula, you may be able to
identify it as a base.
 Bases often behave like bases only when dissolved in water.
 Therefore, bases are often written with the symbol (aq) = aqueous = water.
• The chemical formula of a base usually ends with hydroxide (OH).
• Bases can be gentle or very caustic.
• Examples of common bases:




NaOH(aq)
Mg(OH)2(aq)
Ca(OH)2(aq)
NH4OH(aq)
See page 227
(c) McGraw Hill Ryerson 2007
Production of Ions
• Acids and bases can conduct electricity because they
release ions in solution.
 Acids release hydrogen ions, H+ .
 Bases release hydroxide ions OH–.
• The pH of a solution refers to the concentration of ions it has.
 Square brackets are used to signify concentration, [H+], [OH–]
 High [H+] = low pH, very acidic
 High [OH–] = high pH, very basic
 A solution cannot have BOTH high [H+] and [OH–]; they cancel each other out
and form water. This process is called neutraliztion.
 H+ + OH–  H2O
See page 228
(c) McGraw Hill Ryerson 2007
Properties of Acids and Bases
Take the Section 5.1 Quiz
See page 229
(c) McGraw Hill Ryerson 2007