Chemistry Lab Chemistry Lab EquipmentEquipment
BeakersBeakers
Wide mouth gas collecting bottles Wide mouth gas collecting bottles with glass plateswith glass plates
Test tube brushesTest tube brushes
Flint Burner LighterFlint Burner Lighter
Crucible and LidCrucible and Lid
Graduated CylinderGraduated Cylinder
Evaporating DishEvaporating Dish
Medicine droppersMedicine droppers
Erlenmeyer FlaskErlenmeyer Flask
Chemical ForcepsChemical Forceps
Glass FunnelGlass Funnel
Red and Blue Litmus PaperRed and Blue Litmus Paper
Spot PlateSpot Plate
Micro Spatula and Scoop SpatulaMicro Spatula and Scoop Spatula
Plastic SpoonPlastic Spoon
Stirring RodsStirring Rods
Hand Test Tube HolderHand Test Tube Holder
Test Tube Rack and Small Test TubesTest Tube Rack and Small Test Tubes
Standard Test TubesStandard Test Tubes
Watch GlassWatch Glass
Beaker TongsBeaker Tongs
Bunsen BurnerBunsen Burner
Crucible TongsCrucible Tongs
Lab Apron (Folded)Lab Apron (Folded)
Ring Stand and ClampsRing Stand and Clamps
Plastic Test Tube RackPlastic Test Tube Rack
Water Trough for Collecting GasWater Trough for Collecting Gas
Wire Gauze with Ceramic CenterWire Gauze with Ceramic Center
Wire Triangle with PorcelainWire Triangle with Porcelain
Centigram BalanceCentigram Balance
Analytical BalancesAnalytical Balances
Buret on ring standBuret on ring stand
Combustion spoonCombustion spoon
DesiccatorDesiccator
Florence flaskFlorence flask
Gas collecting tubeGas collecting tube
Mortar and PestleMortar and Pestle
Pipets and Pipet bulbPipets and Pipet bulb
ThermometersThermometers
Triangular file for glass cuttingTriangular file for glass cutting
Wash bottleWash bottle
Volumetric flasksVolumetric flasks
Separatory funnelSeparatory funnel
Buchner funnel and side arm filter flaskBuchner funnel and side arm filter flask
Mathematics of ChemSI Prefixes can be used with SI bases to form units that are < or > than the base unit by multiples of 10.
Prefix Symbol Multiply root byMega M 1,000,000
Kilo k 1,000
Hecto h 100
deka dk 10
BASE g,l,m 1
deci d .1
centi c .01
milli
micronano
m
μ
n
0.001 1/1000
.000001 1/1000000
.000000001
Using dimensional analysis to convert from one unit to the next
Example – How many minutes are in 3 hours?
3 hours 60 min hour
X = 180 min
Only unit left is the unit we want as our final answer
Hours cancel out
conversion factor
How many hours are in 230 minutes?
230 minutes 60 min hour
We want hours in the numerator, and we want minutes to cancel out
Flip the conversion factor 60 min hour
Hour60 minsame as
230 minutes Hour 60 min
X = 230 hours 60
= 3.8 hours
Ex. 0.19 cm = ? m
0.19 cm x1 m100 cm
This is a conversion factor!!! The top and the bottom number are the same amount!!
Ex. 37 mg = ? g
37 mg
x 1g
1000 mg
Ex. 37 mg = ? kg
37 mg
x 1 g1000 mg
x 1 kg1000 g
Practice
9.923 km = ? m
232 ml = ? dkl
320 hr = ? sec
Sometimes it is easier to use more than one conversion factor!!!
If we sell 2 cars per hour, and we make a profit of $100 for every three cars, how much can we make in 3 hours?
STEPS1. Write out all the numbers with the units2. Write out the units for the answer3. Flip the fractions to allow the units to cancel out4. Multiply and divide
2 carshour
$ 1003 cars
3 hours = $
$ 200
If there are 5 oranges in a box, and each orange weighs
0.5 pounds, and the price is $1.25 per pound, how many
boxes can we buy with $3.00?
5 oranges 1 box
orange0.5 lbs
$1.25 lb
$3.00
0.96 boxes
What are the conversion factors?
Accuracy
- How close a measurement is to an accepted value
- BP of water is 100 C
Precision
- How well a measurement can be repeated
- Measurements are very close to one another
Ex. 1.11, 1.12, 1.10
Uncertainty in Measurement
When taking measurements, measure to the furthest confirmed data point and then estimate one more. The last digit is uncertain.
All measurements vary in their degree of accuracy.
1 M
1.1 M
1.12 MMore accurate
Signigicant Figures
More sig.figs. = More accurate measurement
When making measurements, we are certain of all numbers except the last
- the numbers known with certainty plus one uncertain number
0 1 2 3 4 5 6 7cm
Measure the length as accurately as possible
We know it is between 6 and 7, so we can guess it is 6.6 cm long
a.
706050403020100
b.
46oC
1.81.71.61.51.41.31.21.1
c.
1.54 ml
The last digit is uncertain. We have to make an educated guess as to its value!!!
Why is it uncertain?
1) Limits of the measuring device2) Human error
Rules for Counting Sig Figs in a measurement
1. All nonzero digits are significant-They are always part of the measurement
2. Zeros are significant except in two cases
a. When there is no decimal, the ending zeros are not significant
210 15,000 10,0002 sig figs
2 sig figs
1 sig figs
Ex. 5.37 3 s.d.
40.2935 s.d.
b. With numbers less than 1, the beginning zeros are not significant
0.215 0.0025 0.005203 sig figs
Practice - determine the number of sig figs in the following numbers
432 730 65.0 8400 0.004501 0.850 101.0
3 2 3 2 4 3 4
Calculating with Sig Figs
1. Adding and subtracting
1.) Add or subtract normally
2 sig figs
3 sig figs
2.) Round sum or difference so that it has the same number of decimal places as number having the fewest
632.62.71+
43.7176.952
+ 4635.31635.3 124.662125
2. Multiplication and Division
Multiply or divide normally, then round off to the LEAST NUMBER OF SIG FIGS
16.0x 2.0
32.0
3 sig figs2 sig figs
The answer can only have 2 sig figs
32
18.009.00
=
The answer can only have 3 sig figs
4 sig figs3 sig figs
2.00
Examples - Perform the following calculations, then leave your answer in the proper number of sig figs.
a. 47.0 + 2.938 =
b. 63.8 x 2.0 =
c. 1,400 2.00 =
d. 6.35 + 2.9314 + 120 =
e. 0.250 x 120.0 =
49.938 49.9
127.6 130
700 700.
129.2814 130
30 30.0
f. (1.2 x 103)(6.4 x 104) = 7.68 x 107 7.7 x 107
Scientific Notation
A x 10n
A is a number between 1 and 10
n is an integer
101 = 10
100 = 1
10-1 = .1
So a number written in S.N. could look like
2.2 x 101 =
5.88 x 10-1 =
22 .588
Why do it?
602,000,000,000,000,000,000,000
Easier to write as 6.02 x 1023
Positive Exponent= number of times decimal is moved to the right
Negative Exponent
= number of times decimal is moved to the left
- The bigger the negative the smaller the number
- in scientific notation all numbers written in first factor are significant
Multiplication and Division with Scientific Notation
Multiplication
1. Multiply ordinary parts of number
2. Add exponents
3. Express answer with proper form ( only one number to the left of the decimal point)
4. Make sure the answer has same number of sig. Figs as factor with the least.
Ex. 2.40 x 104 x 6.3 x 102
15.120 x 106 NOPE!!!
1.5120 x 107 Not yet!!
1.5 x 107
Absolutely!!!
Division
1. Divide first factors
2. Subtract exponent in denominator from exponent in numerator
3. Express in proper form ( 1 digit left of decimal )
4. Make sure proper number of sig. figs
Ex. 6.4 x 1061.7 x 102
3.8 x 104
Addition and Subtraction
1. Manipulate the numbers so that they have the same exponents
2. Add/subtract the first numbers and then add the x by 10n to the power
3. Make sure answer is in proper scientific notation, don’t worry about sig figs.
Ex. (8.41 x 103) + (9.71 x 104) =
(6.3 x 10-2) – (2.1 x 10-1)