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Laboratory Equipment
Watch Glass
Evaporating Dish
Beaker
Erlenmeyer
Flask
44 mm Crucible Lid
Filter Flask
Florence Flask
Weighing Dish
17 mL Crucible
Test Tube Holder
Clamp
Mortar and Pestle
Spatulas and Scoops
Ring
Forceps
©Hayden-McNeil, LLC
Stirring Rod
Litmus Paper
Safety Goggles
Ring Stand
Spotting Plate
Tongs
Test Tube Brush
Clamp Holder
Hot Plate
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• Laboratory Equipment
©Hayden-McNeil, LLC
Thermometer, –20°C – 100 °C
Test Tubes
Dropper/Beral
Pipets
Pasteur Pipet
Graduated Cylinders
Buret
Test Tube Rack
Appendix
Buret Clamp
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Ruler
Centrifuge
Büchner
Funnel
Plastic
Wash Bottle
Funnel
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Volumetric
Flask
Petri Dish
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Units and Constants
Table B.1. International System of Units (SI Units)
Quantity
Unit
Abbreviation
mass
kilogram
kg
length
meter
m
time
second
s
temperature
Kelvin
K
amount of substance
mole
mol
electric current
Ampere
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Table B.2. SI Derived Units
Quantity
volume
SI Unit
dm3
m
s
acceleration
m
s2
energy
Alternate Units
liter
L
Newton
N
Joule
J
Hertz
Hz
Pascal
Pa
watt
W
volt
V
m3
velocity
force
Alternate Name
kg m
s2
kg m2
s2
kg
density
m3
g
cm3
frequency
pressure
power
electric potential
1
s
kg
m s2
kg m2
s3
kg m2
s3 A
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B • Units and Constants
Table B.3. SI Prefixes
Prefix
Symbol
Meaning
tera
T
1012
giga
G
109
mega
M
106
kilo
k
103
hecto
h
102
deca
da
101
deci
d
101
centi
c
102
milli
m
103
micro
µ
106
nano
n
109
pico
p
1012
When using the prefixes for conversions, there are two ways to set up the conversion factor, as shown below.
Example:
or
How many nm in 1 m?
1m e
109 nm
o 1 109 nm
1m
1m e
1m
9
o 1 10 m
10 9 nm
Either calculation is correct and both give the same answer. It just depends on whether you want to think of
1 m 1 109 nm or 1 nm 1 109 m.
Appendix
B
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• Units and Constants Table B.4. Conversion Factors
Length
1 inch 2.54 cm (exactly)
1 mile 5280 ft
1 m 39.37 in
1 km 0.6215 mi
1 light-year 9.46 1015 km
1 Å 1 1010 m
Volume
1 cm3 1 mL
1 quart 0.9463 L
1 fluid ounce 29.57 mL
1 gallon 3.785 L
1 gallon 4 quarts
1 quart 2 pints
Mass
1 pound 16 oz
1 pound 453.6 g
1 kg 2.205 pounds
Temperature
T(K) T(°C ) 273.15
5
T (°C) [T (°F) 32]
9
Pressure
1 atm 1.013 105 Pa
1 atm 760 mm Hg
1 atm 14.70 lb/in2
1 mm Hg 1 torr
Energy
1 J 0.2390 calories
1 Calorie 1 kcal 1000 calories
1 BTU 1055 J
1 kWh 3.6 106 J
1 eV 1.60 1019 J
Table B.5. Constants
Constant
Abbreviation
Value
Planck’s constant
h
6.6256 1034 J∙s
Avogadro’s number
6.0221367 1023
Charge on an electron
e
1.6022 1019 C
Electron radius
re
2.81792 1015 m
Mass of an electron
9.109387 1028 g
Mass of a proton
1.672623 1024 g
Mass of a neutron
1.674928 1024 g
Atomic mass unit
amu
Molar volume
Gas constant
1.66057 1027 kg
22.41383 L/mol
R
J
8.314
K : mol
0.0820g
Speed of light
c
Acceleration due to gravity
g
Rydberg constant for hydrogen
RH
Appendix
B
L : atm
K : mol
2.99792458 108 m/s
9.81
m
s2
1.0967758 107 m1
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Appendix
B
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B • Units and Constants
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Ions
Common Monatomic Ions
Monatomic ions not following general rules for charge. There are other possible ions
for many of these metals but these are the most common and are the ones you are
responsible for knowing.
Name
Formula
Chromium
Cr3
Manganese
Iron
Mn2
Fe
2
or Fe3
Cobalt
Co2 or Co3
Nickel
Ni2 or Ni3
Copper
Cu or Cu2
Zinc
Zn2
Silver
Ag
Cadmium
Cd2
Tin
Mercury
Lead
Sn2
Hg2
2
or Hg2
Pb2
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C • Ions
Polyatomic Ions
Name
Formula
Ammonium
NH4
Carbonate
CO32
Hydrogen carbonate or bicarbonate
HCO3
Hypochlorite
ClO
Chlorite
ClO2
Chlorate
ClO3
Perchlorate
ClO4
Chromate
CrO42
Dichromate
Cr2O72
Cyanide
CN
Thiocyanate
SCN
Hydroxide
OH
Nitrate
NO3
Nitrite
NO2
Phosphate
PO43
Hydrogen phosphate
HPO42
Dihydrogen phosphate
H2PO4
Permanganate
MnO4
Peroxide
O22
Sulfite
SO32
Sulfate
SO42
Hydrogen sulfate or bisulfate
HSO4
Oxyanions and Oxyacids
Appendix
C
Description
2 less oxygens than “ate” compound
Hypo
Per
ate
ous acid
ous acid
ate
MEMORIZE
1 more oxygen than “ate” compound
Acid
ite
ite
1 less oxygen than “ate” compound
Example:
94
Anion
Hypo
ic acid
Per
ic acid
Sulfate is SO42, remove two of the oxygens to get hyposulfite (SO22), which becomes hyposulfurous acid
(H2SO2) with the addition of two hydrogens.
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Solubility
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Solubility Rules
1. Compounds containing alkali metal ions (Li, Na, K, Rb, Cs) and the ammonium
ion NH4 are soluble.
2.
Nitrates (NO3), bicarbonates (HCO3), and chlorates (ClO3) are soluble.
3.
Halides except Ag, Hg22, and Pb2 are soluble.
4.
Sulfates (SO42) are soluble, except Ag, Hg22, Pb2, Ca2, Sr2, and Ba2.
Insolubility Rules
1. Carbonates (CO32), phosphates (PO43), chromates (CrO42), and sulfides (S2) are
insoluble except for those containing alkali metal or ammonium ions.
2.
Hydroxides (OH) are insoluble except for those containing alkali metals or Ba2
ions.
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D • Solubility
Ksp Values for Some Common Salts
Appendix
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Compound
Formula
Ksp
aluminum hydroxide
Al(OH)3
4.6 1033
barium carbonate
BaCO3
5.1 109
barium chromate
BaCrO4
2.2 1010
barium hydroxide
Ba(OH)2
5 103
barium sulfate
BaSO4
1.1 1010
calcium carbonate
CaCO3
3.8 109
calcium fluoride
CaF2
5.3 109
calcium hydroxide
Ca(OH)2
5.5 106
calcium phosphate
Ca3(PO4)2
1 1026
copper(I) chloride
CuCl
1.2 106
copper(I) sulfide
Cu2S
2.5 1048
copper(II) chromate
CuCrO4
3.6 106
copper(II) hydroxide
Cu(OH)2
2.2 1020
iron(II) carbonate
FeCO3
3.2 1011
iron(II) hydroxide
Fe(OH)2
8.0 1016
iron(II) sulfide
FeS
6 1019
iron(III) hydroxide
Fe(OH)3
4 1038
lead(II) chloride
PbCl2
1.6 105
lead(II) chromate
PbCrO4
2.8 1013
lead(II) hydroxide
Pb(OH)2
1.2 105
lead(II) sulfate
PbSO4
1.6 108
lead(II) sulfide
PbS
3 1029
lithium carbonate
Li2CO3
2.5 102
lithium fluoride
LiF
3.8 103
magnesium carbonate
MgCO3
3.5 108
magnesium fluoride
MgF2
3.7 108
magnesium hydroxide
Mg(OH)2
1.8 1011
magnesium phosphate
Mg3(PO4)2
1 1025
nickel(II) carbonate
NiCO3
6.6 109
silver bromide
AgBr
5.3 1013
silver carbonate
Ag2CO3
8.1 1012
silver chloride
AgCl
1.8 1010
silver chromate
Ag2CrO4
1.1 1012
silver iodide
AgI
8.3 1017
silver nitrite
AgNO2
6.0 104
silver sulfide
Ag2S
6 1051
silver sulfite
AgSO3
1.5 1014
zinc carbonate
ZnCO3
1.4 1011
zinc hydroxide
Zn(OH)2
1.2 1017
zinc sulfide
ZnS
2 1025
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Standard Deviation
E
In most real experiments, the “true” value of a quantity is not known. Therefore, we
must find a way to use our data to get the best possible estimate of the true value for
the quantity being determined. One common estimate of the true value is the mean
(X ) . The mean is simply the arithmetic average of all the data points:
X
where
/X
n
i
X1 X 2 X 3 … X n
n
X the mean value (or average),
Σ “the sum of,”
Xi the individual data points (i 1, 2, 3, …, n), and
n the total number of data points.
One way to express precision is by means of the standard deviation. To discuss this, we
must first discuss the normal distribution.
If a very large number of determinations of a quantity are done, all of the values will
not be exactly the same, due to random errors.
On these graphs, X represents the mean, which is the best estimate of the true value.
The width of the curve indicates the precision of the measurements. A tall, thin curve
would indicate good precision, while a broad, flat curve would show poor precision.
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E
• Standard Deviation
The standard deviation can be used to measure the
width of a normal distribution. The standard deviation
is defined as:
s
/ (X
Step 1: Calculate the sum of the data: Σ Xi 13.60
Step 2: Calculate the average of the values:
X )2
(n 1)
i
X
where s the standard deviation, n the number of
observations.
The usefulness of the standard deviation is that it is
expressed in units of the original measurement, and can
be used to describe the position of any observation relative to the mean. It can be shown mathematically that,
for a distribution with an infinite number of replicate
measurements, 68.3% of the observed values will fall
within ± 1s of the mean; 95.5% will fall within ± 2s of
the mean; and 99.7% within ± 3s of the mean.
Frequency
n
i
13.60
2.720
d
Step 3: Calculate the deviation of each result
(d | Xi X | ), the sum of the deviations (Σ | d | ), the
square of d values ( | d |2 ), and the sum of the square of
the d values (Σ | d |2 ). Tabulate these values in a new table:
Experiment
Number
Xi
| Xi X |
| Xi X |2
1
2.60
| 2.60 2.720 | 0.12
0.014
2
2.90
| 2.90 2.720 | 0.18
0.032
3
2.70
| 2.70 2.720 | 0.020
0.00040
4
2.90
| 2.90 2.720 | 0.18
0.032
5
2.50
| 2.50 2.720 | 0.22
0.048
n5
68%
/X
Σ Xi 13.60
Σ (Xi X )2 0.13
Step 4: The standard deviation can then be calculated
from the formula:
95%
s
99%
-3s
-2s
-1s
+1s +2s
Measured characteristic
+3s
Figure E.1.
Example
Suppose that a density determination of a liquid is done
in the laboratory, and the following data are obtained:
Appendix
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Experiment Number
Density (g/mL)
1
2.60
2
2.90
3
2.70
4
2.90
5
2.50
From this data, calculate the average and standard deviation for the results.
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0.13
0.177
5 1
Thus, we could state that the result of the density
determination together with its standard deviation is
2.72 ± 0.18 g/mL. (Note that the average cannot have
more significant figures than the measurements that
make up the average and that the standard deviation
has the same number of decimal places as the average.)
The value of the standard deviation gives us some idea
of the spread of our data points, or the precision of our
determinations. A student with a standard deviation in
this case of 0.100 will have a higher degree of precision
in his or her experiment, but it does not necessarily
mean that the experiment has a high degree of accuracy.
It is very important to realize at this stage that
you can have a very small deviation in your data
(indicating high precision) but your result may
be significantly off (if the accuracy is low).