Chemistry 1A Dr. Baxley
If you are enrolled in the class, please sit at
the tables.
Take a syllabus, I will take roll by section.
If you are NOT enrolled but wish to ADD,
•Please sit on the stairs or stand at the back.
•DO NOT take a syllabus yet.
•You must sign a wait list.
• Lab sections:
4240
4241
4242
4243
T
Th
Th
F
1:30 −4:30 pm
8:30 −11:30 am
12:30 −3:30 pm
12:30 −3:30 pm
• Lab section # must be on everything you turn in
Dr. Baxley’s website:
http://academic.cuesta.edu/gbaxley
Web discussion board
http://cuesta-genchem.cvc4.org:8080/
Linked on website
Study 25-35 hours per week
15 hours class + 25-35 hours studying
= 40-50 hours/week
Drop in Peer tutors needed for Chem 10, see me
Chem 10 FAL leaders needed,
see Professor Clark (2303) or
Professor Jimison (2304)
1
Concept check:
How we learn:
• No one can “learn” you
• Teaching and Learning have 3 components:
content, doing, and evaluation
• I can’t read the text for you, or tell you everything
• Being challenged is far better than being bored
• Learning must be a positive experience
• Learning chemistry will make you better at learning
everything else
• Be a long jumper, not a hurdler (Mastery)
A time for students to discuss what they think,
and get feedback on questions. You must talk!
After transferring, how many of Dr. Baxley’s
former students say that Chem 1A should have
been even harder (so they’d be better prepared)?
1. About 10%
2. About 50%
3. Nearly 100%
• This class is designed for you to succeed
Matter: all stuff that has mass ( chocolate, air, rocks)
A molecule is made of two or more atoms
“bonded” together .
Atoms are the building blocks of matter.
Each element is made of the same kind of atom.
A compound is made of two or more different
kinds of atoms stuck together by “bonds”.
Which of the above are molecules?
1. all
2. the top 3
3. none
4. only the bottom one
Substances and mixtures
Elemental composition
• Pure substance: specific type of matter (water, sucrose)
• Mixture: more than one substance in a sample.
– Homogeneous: mixture is uniform, also called solutions
Figure 1.6
– Heterogeneous: mixture is NOT uniform throughout
• mixtures: can be separated by physical means
• Heterogeneous mixture: has varying composition (cookie)
Earth’s Crust
Human Body
Universe: 73% Hydrogen 24% Helium 2% C, N, O, Ne
1% everything else
• A pure substance is homogeneous and cannot be separated
by physical means
• a compound can be decomposed into other substances
• If a pure substance can’t be decomposed, it’s an element
2
Mixture flow
chart
Classifying Matter
Figure 1.9
Classify the substances on the right:
A. Which column represents mostly pure
substances and which mostly mixtures?
1
B. Which substances are in the
wrong column?
2
1 (pure)
2 (mixtures)
Milk
Raisin Bran
Milk
Raisin Bran
Sodium chloride
Chocolate
Sodium chloride
Chocolate
flawless diamond Air
flawless diamond Air
Graphite
sucrose
Graphite
sucrose
water
tea
water
tea
Separation of
mixtures
Paper Chromatography
3 ink spots on paper
3
Paper Chromatography
• Link to fingerprinting
Units of Measurement
• Memorize units of measurement
• Prefixes to show powers of ten are used for
convenience
4
Units of Measurement
Scientific Notation
Memorize Greek prefixes and meanings
Easier way to write large and small numbers
1 gram of carbon has:
50,200,000,000,000,000,000,000
atoms
1 hydrogen atom has a mass of:
0.0000000000000000000000167
g
Scientific Notation
Relate to powers of ten
10
=
1 x 10
Or 1 x 101
100
=
1 x 10 x 10
Or 1 x 102
1000
=
1 x 10 x 10 x 10
Or 1 x 103
10000
=
1 x 10 x 10 x 10 x 10
Or 1 x 104
0.1
=
1 ÷ 10
Or 1 x 10–1
0.01
=
1 ÷ 10 ÷ 10
Or 1 x 10–2
0.001
=
1 ÷ 10 ÷ 10 ÷ 10
Or 1 x 10–3
Sander and Aleta
Scientific Notation
Write the following in scientific notation:
Goal: Write number in decimal form, to a power of 10
345.9 nm
3.459 x 102
0.0054 mL
5.4 x 10–3
instead of 0.000245
Use single digit before decimal: 2.45 [not 24.5]
Multiply by power of ten to represent size
2.45 x 10–4
93,000,000 miles
9.3 x 107
(ave. distance from Earth to Sun)
0.00000050 kg
5.0 x 10–7
5
Convert between metric prefixes
Calculator check:
Math with exponents:
1. Use EE or EXP buttons NOT 10x
2. To enter 1.5 x 10–7, type: 1.5 EE -7
Convert 52 mm to m:
1. Start with measured value
2. multiply by equality as a ratio
3. To calculate 5.25 * [1.5 x 10–7]
type: 5.25 x 1.5 EE –7 =
3. Include units, and cancel!
7.9x10–7
4. Calculate: 15.05 x [1.6x10–3] ÷ [9.46x10–8] =
2.5 x 105
52 mm *
1x10-3 m
mm
1
52 mm * 1 m
1000 mm
Big unit,
Small number,
= 0.052 m
= 0.052 m
Small unit,
large number
Units of Measurement
Volume
More conversions:
1. 45 m to cm
4500 cm
2. 0.012 km to m
12 m
3. 0.000095 km to nm
9.5 x 107 nm
4. 35.8 µs to cs
3.58 x 10-3 cs
• Liters or milliliters (L or mL)
• 1 mL = 1 cm3 = 1 cc
• 1 L = 1000 cm3 = 1000 mL.
Converting volume measurements
Convert 55.5 mL to L
55.5 mL *
Area and Volume conversions
Big unit,
Small number
1 L = 0.0555 L
1000 mL
Make sure all units cancel!
Know: 1 inch = 2.54 cm
1. How many cm2 are in 1 m2?
Small unit,
large number
cm2
are in an object
2. How many
3.94 in x 3.94 in?
1.00x102 cm2
3. How many cm3 are in 1 m3?
1x106 cm3
4. How many cc are in a 125 in3 engine?
If using lengths to calculate area or volume, cancel all units!
10,000 cm2
2.05x103 cc
(cc is short for cubic centimeter)
cm3 = cm x cm x cm
6
STUDY 25-35 hours per week
Temperature
Scales
You CAN succeed!
Convert degree C to K
Temperature
Each 1 degree C = 1 K,Scales
Convert degree C to
degree F
Each 100 oC = 180 oF
so each 1 oC = 1.8 oF
0 oC starts at 273 K
So K = oC + 273
0 oC starts at 32 oF,
Thus F = (C*1.8) + 32
Uncertainty in Measurement
Uncertainty in Measurement
Precision and Accuracy
Precision and Accuracy
7
Significant Figures
• Do all numbers of a measurement have
meaning?
• Do all of those numbers in your calculator
really count?
• A great big meteor crashed into the Earth
65,000,000
65,000,001 years ago.
Real measurements
Can you use this ruler?
• Example:
– I measure the distance from my car to my door
with a tape measure, 145.3 cm.
– With my car odometer, from Cuesta to my
driveway is 20.4 km, so the total distance is
• 145.3 cm + 20.4 km
• (convert to meters) 1.453 m and 20,400 m
• 1.453 m + 20,400 m = 20,401.453 m
– Is this realistic?
0
1
8
Uncertainty in Measurement
• Only report realistic digits in a measurement
• All digits known with certainty + one estimated digit
are significant figures.
Your job as a Junior Apprentice Chemist:
estimate between the last known markings
How many sig figs in each number?
Discuss why.
3.4680
5
34,608
0.3468
4
3,460,800
0.03468
4
3.4600 x 10-2
5
0.034680
5
3.46 x 10-2
3
5
5, 6, 7?
• In calculations, report results to the
fewest sig figs (for multiplication and division)
OR fewest decimal places (addition and subtraction).
Significant figures
• Non-zero #’s are always significant.
• Zeros between non-zero #’s are always sig.
– 1.003 has 4 sig figs
• Zeros before the first non-zero # are not sig.
– 0.0003 has one SF.
• Zeros at end of a # with a decimal are significant
– 450.0 has 4 SF,
0.0015010 has 5 SF
• Zeros at the end of a # w/o a decimal are
ambiguous (e.g. 10,300 g). DON’T USE THEM
Underline the sig figs
Underline the sig figs
a) 303.68 m
a) 303.68 m
a) 303.68 m
b) 0.010 sec
b) 0.010 sec
b) 0.010 sec
5.883×1032 atoms
c) 5.883×1032 atoms
c) 5.883×1032 atoms
c)
d) 0.001 g
d) 0.001 g
d) 0.001 g
e) 25.0 ml
e) 25.0 ml
e) 25.0 ml
f) 12.20 µg
f) 12.20 µg
f) 12.20 µg
g) 141,000 residents
g) 141,000 residents
g) 141,000 residents
h) 14 eggs (counted)
h) 14 eggs (counted)
h) 14 eggs EXACT NUMBER!
9
Add and subtract
Sig figs in calculations
For multiply/divide, use fewest number of sig figs
measure 7.6 mm x 8.2 mm, area = 62.32
mm2
use fewest decimal places,
Don’t worry about number of sig figs
34.895
But, these are measurements, so it could be:
7.6 mm x 8.3 mm, area = 63.08 mm2
Report to fewest # of SF:
m
+ 0.00098 m
34.896
34.89598
3 d.p.
2.1
5 d.p.
+ 389.453 g
m
g
391.6
Answer must have only 3 d.p.
7.6 mm x 8.2 mm, area = 62 mm2
Practice sig figs
Perform rules according to standard
math operations:
(1.01×107) × (4.059×105)
(319.4 — 318.7) × (4.2 + 9.7)
(3.052 km + 1114.2 m) ÷ 62.12 s
Conversion problems
A 3 oz bag of tortilla chips contains 465 kcal.
1 cal = 4.184 J
453.6g/pound
1 oz = 28.3 g
1. How many kJ of energy in 1 bag of chips?
2. How many kJ of energy are in a 0.75 pound bag?
3. When swimming, your body consumes 2200 kJ/hr,
how many minutes will you have to swim to burn
off the 1 oz bag of chips?
The density of iron is 7.86 g/cm3. What is the
volume of 10.5 g of iron?
Convert the following temperatures
a. 83.2 °C to °F b. 15.8 °F to K
10
Properties of Matter
Physical and Chemical
changes
Matter: all stuff that has mass ( chocolate, air, rocks)
Atoms are the building blocks of matter.
Each element is made of the same kind of atom.
A compound is made of two or more different
kinds of atoms stuck together by “bonds”.
A molecule
is made of two or more atoms
“bonded” together .
Substances and mixtures
• ________________ specific type of matter (water, sucrose)
• __________: more than one substance in a sample.
_______ geneous: mixture is uniform, also called solutions
________ geneous: mixture is NOT uniform throughout
• _________: can be separated by _______________ means
• Heterogeneous mixture: has ________ composition (cookie)
• A ____________ is homogeneous and _____________ be
separated by physical means
Which of the above are molecules?
1. all
2. the top 3
3. none
4. only the bottom one
Mixture flow
chart
• a ____________ can be decomposed into other substances
• If a pure substance can’t be decomposed, it’s an _________
Area and Volume conversions
Make sure all units cancel!
Know: 1 inch = 2.54 cm
1. How many cm2 are in 1 m2?
2. How many cm2 are in an object
3.94 in x 3.94 in?
Figure 1.9
3. How many cm3 are in 1 m3?
4. How many cc are in a 125 in3 engine?
(cc is short for cubic centimeter)
11
How many sig figs in each number?
Discuss why.
Underline the sig figs
a) 303.68 m
3.4680
34,608
b) 0.010 sec
0.3468
3,460,800
c) 5.883×1032 atoms
0.03468
3.4600 x 10-2
d) 0.001 g
0.034680
3.46 x 10-2
e) 25.0 ml
f) 12.20 µg
g) 141,000 residents
h) 14 eggs (counted)
Significant figures
• Non-zero #’s are always significant.
• Zeros between non-zero #’s are
– 1.003 has _________ sig figs
• Zeros before the first non-zero # are
– 0.0003 has _________ SF.
• Zeros at end of a # with a decimal are significant
– 450.0 has _____ SF,
0.0015010 has _____ SF
• Zeros at the end of a # w/o a decimal are
ambiguous (e.g. 10,300 g).
Conversion problems
A 3 oz bag of tortilla chips contains 465 kcal.
1 cal = 4.184 J
453.6g/pound
1 oz = 28.3 g
1. How many kJ of energy in 1 bag of chips?
2. How many kJ of energy are in a 0.75 pound bag?
3. When swimming, your body consumes 2200 kJ/hr,
how many minutes will you have to swim to burn
off the 1 oz bag of chips?
12