Homework assignment
Due 9/12/06
• Chapter 1
– 18, 22, 32, 39, 46, 50, 55, 66
CHE107 Lab Organization
• Starts Monday (9/11/06)
• Meet here
• You need (ie. bring to lab)…
– Lab manual (Red)
– Bound lab notebook
– Safety goggles
– Close-toed shoes (Safety 1st!!)
CHE107 Lab Organization
• Before lab:
– Read the section of the lab manual
– Answer the pre-lab questions (p.15)
• These are to be handed in at the beginning of lab!
– Start your lab notebook
• Title, purpose, procedures, balanced equation(s),
etc.
CHE107 Lab Organization
• During lab
– Write down observations (measurements, etc)
in your notebook
– Follow your written procedures
– Write down changes to the pre-lab procedures
CHE107 Lab Organization
• After lab
– Write lab report, including post-lab questions
• Grading
– Pre-lab questions
– Lab report
– Laboratory notebook (midterm & final)
• “Disco Lab”
• Wednesday 1:30-4:20
Next week’s lab: “The Bean Lab”
• Series of measurements
– Average/mean
– Standard deviation
• How much do your values ‘vary’?
– Differences in individual
– Errors in measurements
• Mean/Standard deviation calculations:
– Hand
– Calculator
– Computer (Excel spreadsheet)
Simplifying numbers…Prefixes
Simplify 30,000 m.
30 mm is how many meters (m) ?
Simplifying numbers: Scientific Notation
The number of atoms in 12 g of carbon:
602,200,000,000,000,000,000,000
6.022 x 1023
The mass of a single carbon atom in grams:
0.0000000000000000000000199
1.99 x 10-23
N x 10n
N is a number
between 1 and 10
n is a positive or
negative integer
Scientific Notation
568.762
N x 10n
0.00000772
move decimal left
move decimal right
n>0
n<0
568.762 = 5.68762 x 102
0.00000772 = 7.72 x 10-6
Scientific Notation
Addition or Subtraction
1. Write each quantity with
the same exponent n
2. Combine N1 and N2
3. The exponent, n, remains
the same
4.31 x 104 + 3.9 x 103 =
4.31 x 104 + 0.39 x 104 =
4.70 x 104
Scientific Notation
Multiplication
1. Multiply N1 and N2
2. Add exponents n1 and n2
Division
1. Divide N1 and N2
2. Subtract exponents n1 and n2
(4.0 x 10-5) x (7.0 x 103) =
(4.0 x 7.0) x (10-5+3) =
28 x 10-2 =
2.8 x 10-1
8.5 x 104 ÷ 5.0 x 109 =
(8.5 ÷ 5.0) x 104-9 =
1.7 x 10-5
35,000 x 0.012 = 4.2 x 102
Working with numbers
Gen Chem edition
• Dimensional analysis
– Convert units
• 3.5 days = x seconds ?
Dimensional Analysis Method of Solving Problems
How many mL are in 1.63 L?
1. Determine which unit conversion factor(s) are needed
1 L = 1000 mL
2. Carry units through calculation
How many seconds in 3.5 days?
3.024 x 105 seconds
1000 mL
1.63 L x
= 1630 mL
1L
3. If all units cancel except for the desired unit(s), then the
problem was solved correctly.
2
1L
L
1.63 L x
= 0.001630
1000 mL
mL
1.9
The speed of sound in air is about 343 m/s. What is
this speed in miles per hour?
meters to miles
seconds to hours
1 mi = 1609 m
1 min = 60 s
1 mi
60 s
m
x
x
343
s 1609 m
1 min
1 hour = 60 min
60 min
mi
x
= 767
hour
1 hour
Density – SI derived unit for density is kg/m3
1 g/cm3 = 1 g/mL = 1000 kg/m3
mass
density =
volume
m
d= V
A piece of platinum metal with a density of 21.5
g/cm3 has a volume of 4.49 cm3. What is its mass?
m
d= V
m = d x V = 21.5 g/cm3 x 4.49 cm3 = 96.5 g
Three Temperature Scales
• Fahrenheit
• Celcius (Centigrade)
– Absolute zero = -273.15°C
• Kelvin (K) (SI unit)
– Absolute zero = 0 K
K = 0C + 273.15
273 K = 0 0C
373 K = 100 0C
0F
= 9 x 0C + 32
5
32 0F = 0 0C
212 0F = 100 0C
1.7
Atoms, Molecules and Ions
Chapter 2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Dalton’s Atomic Theory (1808)
1. Elements are composed of extremely small
particles called atoms. All atoms of a given
element are identical, having the same size,
mass and chemical properties. The atoms of one
element are different from the atoms of all other
elements.
2. Compounds are composed of atoms of more
than one element. The relative number of atoms
of each element in a given compound is always
the same.
3. Chemical reactions only involve the rearrangement
of atoms. Atoms are not created or destroyed in
chemical reactions.
2.1
2
2.1
16 X
+
8Y
8 X2Y
2.1
Rutherford’s Model of
the Atom
atomic radius ~ 100 pm = 1 x 10-10 m
nuclear radius ~ 5 x 10-3 pm = 5 x 10-15 m
“If the atom is the Houston Astrodome, then
the nucleus is a marble on the 50-yard line.”
2.2
mass p = mass n = 1840 x mass e2.2
Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Isotopes are atoms of the same element (X) with different
numbers of neutrons in their nuclei
Mass Number
A
ZX
Atomic Number
1
1H
235
92
2
1H
U
Element Symbol
(D)
238
92
3
1H
(T)
U
2.3
2.3
Do You Understand Isotopes?
How many protons, neutrons, and electrons are
14
in 6 C ?
6 protons, 8 (14 - 6) neutrons, 6 electrons
How many protons, neutrons, and electrons are
11
in 6 C ?
6 protons, 5 (11 - 6) neutrons, 6 electrons
2.3