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BRCC
CHM 101
Class Notes
Chapter 1
Page 1 of 7
Chemistry - the study of matter, its behavior and interactions.
matter - anything that takes up space and has mass
mass - the substance which makes up the physical world; mass is made of atoms and is constant
weight - a measure of mass that depends on gravity; weight changes depending on where you are
measuring.
modern science - based on systematic gathering of facts and careful observations - science is widely
used to guide the development of technology
scientific method - 4 step process:
1. make observations and collect data
2. propose a hypothesis
3. test the hypothesis
4. accept or reject the hypothesis -
* If strongly supported by data, a hypothesis may
become a theory.
exponential notation - a way to handle very large or very small numbers - it is based on powers of 10
3
ex. 1,000 = 10 x 10 x 10 or 10
* The exponent indicates the number of times we multiply 10 by itself and how many zeros follow
6
the one. ex. 10 means that there are six zeros after the 1 or 1,000,000
* There are also negative powers of 10 in which you divide by the number of 10’s indicated.
10
-4
1
1
= ------ = ------------ = .0001
4
10
10,000
* Numbers are often expressed as a coefficient with an exponent.
3
ex. 6.4 x 10 = 6.4 x 1,000 = 6,400
-5
2.7 x 10
= 2.7 x .00001 = .000027
rules for writing in scientific notation:
1. When writing numbers in scientific notation, coefficients have only one digit to the left of the
decimal. ex. 2.5431
2. If you need to move the decimal to the left, then your exponent is a positive number indicating
the number of times you must move the decimal to put it in scientific notation.
4
ex. 58,652 = 5.8652 x 10
3. If you need to move the decimal to the right, your exponent will be negative.
-3
ex. .00346 = 3.46 x 10
BRCC
CHM 101
Class Notes
Chapter 1
Page 2 of 7
rules for calculating with exponents:
1. Adding and Subtracting - adding and subtracting exponents are allowed only if the numbers
have the same exponent. Add or subtract the coefficient and leave the exponent alone.
ex.
-3
2.5 x 10
-3
+ 3.0 x 10
--------------------3
5.5 x 10
2. Multiplication - multiplying is a 2 step process: (1) multiply the coefficients (2) add the
exponents
5
ex.
7.40 x 10
9
x 3.12 x 10
----------------------14
15
23.1 x 10
-------------------> 2.31 x 10
3. Division - dividing is a 2 step process: (1) divide the coefficients (2) subtract the exponents
8
ex.
6.4 x 10
6.4
------------------ first -------- = 2.5
10
2.57 x 10
2.57
8
10
-2
-2
then ------- = 10 so that it is 2.5 x 10
10
10
measurement - there are always 2 parts to a measurement: a number and a unit *always give the
units. ex. 68 lbs is different from 68 oz.
* science uses SI units (International System of Units) which are meter, kilogram, Kelvin
* chemistry units of measurement: meter, liter, gram, second, Kelvin or Celsius degree
•
prefixes are used to convert to smaller or larger units
Prefix
giga
mega
kilo
hecto
deca
deci
centi
milli
micro
nano
Symbol
G
M
K
h
da
d
c
m
µ
n
* memorize these prefixes
Value
10 = 1,000,000,000
6
10 = 1,000,000
3
10 = 1,000
2
10 = 100
10
-1
10 = 0.1
-2
10 = 0.01
-3
10 = 0.001
-6
10 = 0.000001
-9
10 = 0.000000001
9
BRCC
CHM 101
Class Notes
Chapter 1
Page 3 of 7
length - basic unit is the meter, which is about 39 inches - a little longer than a yard
ex. 1 kilometer (km) = 1,000 meters (m)
1 centimeter (cm) = 0.01 meter
volume - the space occupied by something - the basic unit is the liter (L) - a little bigger than a quart
ex. 1,000 milliliter (mL) = 1 liter (L)
* the mL is common in chemistry
1 cubic centimeter (cc) = 1 mL
* an important relationship to remember
mass - the quantity of matter in an object - basic unit is the gram (g) - there are about 454 g in a lb
ex. 1 kilogram (kg) = 1,000 g
1,000 milligrams (mg) = 1 g
* things to remember: (1) We measure mass with a balance.
(2) Mass and weight are different - mass is independent of where you are
and weight depends on gravity.
(3) We can use them interchangeably on earth.
time - the basic unit is the second (s) -
60 s = 1 min
& 60 min = 1 hr
temperature - the Celsius or centigrade scale is the common standard - Kelvin is the SI standard
method to convert between Fahrenheit and Celsius
Fahrenheit
-- --
boiling point of H2O
Celsius
212 °F
-- --
100 °C
<------ 100 degrees
180 degrees ------->
freezing pt of H2O
-- --
32 °F
-- --
0 °F
-- --
0 °C
* For Fahrenheit, between the freezing point and boiling point of water there are 180 degrees.
* For Celsius, between the freezing point and boiling point of water there are 100 degrees.
100
-----180
5
= ----9
and
180
-----100
9
= ----5
= 1.8
* Which degrees are bigger? Celsius degree is larger because there are more (smaller) Fahrenheit
degrees.
BRCC
CHM 101
Class Notes
Chapter 1
Page 4 of 7
* To convert from °F to °C first subtract 32 degrees and then multiply by 5/9.
5
°C = (°F - 32 °F) x ---9
* To convert from °C to °F first multiply by 9/5 (or 1.8) and then add 32 degrees.
9
°F = (°C x ---- ) + 32
5
or (°C x 1.8) + 32
Kelvin (K) scale is absolute - this means 0 K is absolute zero! Do not use the degree symbol ° with
Kelvin degrees.
K = °C + 273.15
Temperature Comparisons
Celsius Temperature (°C)
Fahrenheit Temperature (°F)
Description
0
32
Freezing Point of water
21
70
Room Temperature
25
77
Standard Temperature
37
98.6
Body Temperature
64
147
Too hot to hold > 4 sec.s
100
212
Boiling Point of water
unit conversions
dimensional analysis - (also called factor-label method) is a method of working through complex
problems using units and conversions.
* When multiplying numbers we also multiply units and when dividing numbers we also divide units
* conversion factor - a ratio of 2 different units
ex. convert 381g to lbs
you know there are 453.6 g in 1 lb
so there are 2 possible conversion factors :
381 g
1 lb
x ------------- = 0.840 lb
453.6 g
453.6 g
--------------1 lb
or
1 lb
-------------453.6 g
BRCC
CHM 101
Class Notes
Chapter 1
Page 5 of 7
* When using a conversion factor, put the units you want to end up with on top and cancel out the units
you want to get rid of.
ex. convert 132 lbs to kilograms
132 lbs
x
453.6 g
----------1 lb
1 Kg = 1,000 g
1 kg
x ------------- = 59.9 Kg
1,000 g
Conversion Table
Physical Quantity
Conversion
Factor
Length
inches Î cm
1 inch = 2.54 cm
Volume
liters Î quarts
1 L = 1.057 qts.
Mass
pounds Î grams
1 lb. = 453.6 g
The States of Matter
Matter has 3 states:
Solid -
solid, liquid, and gas
solids have a definite shape and volume - they vary in their hardness and brittleness from
substance to substance. Solids are not compressible.
Liquid - liquids have a definite volume and are not compressible. Liquids do not have definite
shapes; they will take the shape of the bottom of their containers and will spread out on a
flat surface.
Gas -
gases do not have either a definite volume or a definite shape; they take both the volume
and the shape of their container and are easily compressible.
Three types of processes will concern us in chemistry:
physical change - substances change their form or phase but not their essential nature. ex. melting,
boiling, dissolving, and grinding into a powder.
chemical change - chemical reaction - one set of substances (reactants) is transformed into another
set of substances (products). ex. combustion.
nuclear reaction - deals with radioactivity. ex. nuclear decay.
Density mass of a substance divided by its volume
d = m / V units are g/mL or g/L (gases)
density is a characteristic property of a substance - a physical property which is constant at
constant temperature and can be used to help identify a substance.
density of a solid or liquid changes with temperature ===> as Temp↑ the density ↓
ex.
If 73.2 mL of a liquid has a mass of 61.5 g, what is the density?
mass
61.5 g
d = ---------- = -------------- = 0.840 g/mL
volume
73.2 mL
BRCC
ex.
CHM 101
Class Notes
Chapter 1
Page 6 of 7
If the density of a piece of metal is 7.86 g/mL, then what is the volume of a piece of that metal
weighing 524 g?
524 g
x
1 mL
--------- = 66.7 mL
7.86 g
Specific gravity - is the density of a substance divided by the density of water (which is usually 1.00
g/mL) specific gravity has no units.
ex.
The density of copper (Cu) at 20 °C is 8.92 g/mL. The density of water at 20 °C is 1.00 g/mL.
What is the specific gravity of Cu?
8.92 g/mL
--------------- = 8.92
1.00 g/mL
which means that copper is 8.92 times as dense as water
extensive properties - properties of a substance which depend on the quantity of material. ex. mass
and volume - these are not useful in identifying a substance.
intensive properties - properties of a substance which are independent of sample size. ex. density,
solubility, boiling point - these are useful in identifying a substance
energy - the capacity to do work - 2 types: kinetic and potential
kinetic energy - energy of motion - increases as an object moves faster
potential energy - stored energy
chemical energy - a form of potential energy released when chemicals react - piece of paper has
chemical energy released when it is burned (chemical reaction)
principle of nature -
objects tend to seek their lowest possible potential energy - this is why water
flows down hill
Law of Conservation of Energy - energy can neither be created nor destroyed - it is converted from
one form to another.
heat - a type of energy - not the same as temperature - heat is measured in calories
calorie, cal, - the amount of heat necessary to raise the temperature of 1 g of H2O by 1 °C
kilocalorie, kcal = 1,000 cal
* nutritionists use the Calorie to mean the same thing as the kcal
heat is also measured in Joules (J)
1 cal = 4.184 J
BRCC
CHM 101
Class Notes
Chapter 1
Page 7 of 7
Specific Heat - the amount of heat (calories) needed to raise the temperature of 1 g of any substance by
1 °C - each substance has its own specific heat
How is specific heat used?
ex.
Heat absorbed = Specific Heat x mass x (T2 - T1)
where T1 = initial temperature & T2 = final temperature
How many calories are required to heat 352 g of water from 23 °C to 95 °C?
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heat = 1.00 cal/g°deg x 352 g x (95 °C - 23 °C) = 2.5 x 10 cal
hypothermia -
condition where body temperature drops - 1 or 2 °C causes shivering - if it drops
more than this, then unconsciousness and death will result.
hyperthermia -
body temperature rises - caused by high outside temperature or fever - a sustained
temperature of 41.7 °C (107 °F) or more is fatal