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MeasuringWelcome to Chemistry 1:
A college preparatory course.
• Cellphone = NO!!!!
• Webpage
• Need to Buy– Scientific Calculator– Notebook or Binder
• Safety Contract – Signed
• Course Expectations– HW & Review (HW Bonus Points)– Make up missed work
• Notes
• Tests
– Getting Extra Help– Shoes in Locker– Letters of recommendation– “Are you a student, or just a kid who comes to
school?”
1. Three specific things you must do to be successful in this course.
2. Three things you must never do (academically) in this course.
Measuring
Hypothesis – testable, educated guess
Theory - repeatedly confirmed hypothesis that has predictive power.
Law – Theory with NO known exceptions
Scientific Method
Measuring
Hypothesis
Theory
Law
Measuring
Science changes!!!!!
MeasuringSpotting Bad Science
1.Based on Anecdotal EvidenceAnecdotal - From stories, not studies (no math)
2.Small Sample Size
3.Not published in Journals – not reviewed or tested
4.Broad ClaimsExample: The Water Cure
Measuring
• Estimated place – every measurement must have ONE estimated place.
• One place past the smallest marking
Measuring
MeasuringMeasuring
MeasuringMeasuring
MeasuringMeasuring
MeasuringMeasuring
MeasuringMeasuring
Measuring
1. Label x and y axis including units
2. Mark Axis using a convenient scale
3. Title your graph “The Dependence of Y on X”
4. Mark dots with a small circle
5. Draw “Best Fit” line or curve
Graphing
Measuring
• Best Fit Line
a. Used ONLY for linear relationships.
b. Fits y = mx + b
m = slope
b = y-intercept
c. If graph is almost perfect line, same # dots above and below
X = independent variable (you can control)
Y = dependent variable (can’t control)
Graphing
Measuring
Measuring
Measuring
• Best Fit Curve
a. Used if points are clearly not linear.
b. Can be fit to higher order eqns:
y = mx2 + b
Graphing
Measuring
Measuring
Rectangle A = L X W
Triangle A = ½ B X H
Circle A = r2
Irregular Shape?
Graphing
Measuring
Measuring
• Use centimeters
• TWO decimal places, last one is the estimated place
• Write down the letter of your shape
• See me for the actual value
Graphing Lab
Measuring
1. What do chemists study/do?
2. What professions/college majors require a chemistry course?
3. Where is chemistry important in business/industry?
4. What household products are “chemicals”?
5. Where in history was chemistry important?
MeasuringScientific Notation
1. Descartes:1637 - “I think, therefore I am”
2. Powers of 10
100 = 1
101 = 10
102 = 10 X 10 = 100
103 = 10 X 10 X 10 =1000
MeasuringScientific Notation
200,000,000,000 stars (Andromeda):
2 X 100,000,000,000
2 X 1011 stars
MeasuringScientific Notation
3. A Helium atom masses
0.000,000,000,000,000,000,000,006,645g
6.645 X 10-24 g
Measuring
340
378,400
0.00234
0.000 000 000 0918
5.6 X 105
6.12 X 10-3
2.6 X 10-7
4 x 102
Scientific Notation
Measuring
43575,4000.0007230.000 000 0014 6.5 X 10-5
2.16 X 103
6.2 X 107
8 x 10-2
Scientific Notation
Measuring
There are ~900 students at Dallas
9 X 102 =90 X 101 =0.9 X 103 =
Scientific Notation
Measuring
Write 4500 in scientific notation with the following exponents:
X 103
X 102
X 105
X 104
Scientific Notation
Measuring
Write 4500 in scientific notation with the following exponents:
4.5 X 103
45 X 102
0.045 X 105
0.45 X 104
Scientific Notation
Measuring
Examples:
(2.0 x 102) + (3.0 x 103) = 3.2 X 103
(6.0 X 103) ÷ (3.0 x 10-5)=2.0X108
(2.0 x 107) - (6.3 x 105) = 1.9X107
Scientific Notation
Measuring
(4.0 x 105) x (3.0 x 10-1)=
(6.0 x 108) ÷ (3.0 x 105)=
(8.4x 1012) ÷ (8.4 x 109)=
NOTE: 103 = 1 X 103
Scientific Notation
Measuring
(4.0 x 105) x (3.0 x 10-1)=1.2 X105
(6.0 x 108) ÷ (3.0 x 105)= 2 X 103
(8.4x 1012) ÷ (8.4 x 109)= 1 X 103
NOTE: 103 = 1 X 103
Scientific Notation
MeasuringAccuracy and Precision
• Accuracy – how close the average of a set of measurements is to the accepted value (AAA)
• Precision – How close a set of measured values are to one another (reproducibility)
• Always compare to a textbook value
Measuring
XX XX
XXX
X
X X
X
X
X
X
X
X
Measuring
Percent Error – Measure of accuracy
% Error = Experimental – Accepted X 100Accepted
NOTE: “Experimental” =average of all trials
Percent Error
Measuring
A student measures the density of a sample of copper at 8.75 g/mL. The accepted value is 8.96 g/mL. Calculate the percent error.
MeasuringError Analysis: Range
Range - Measure of precision
Range = highest trial – lowest trial
Measuring
Example 1
A student measures the density of a sample of lead and does four trials (11.3, 10.5, 11.9, 10.8 g/cm3). Calculate the range and comment on precision.
MeasuringAccuracy and Precision
Students did trials to measure the density of a metal. The accepted density is 7.2 g/cm3. Were they accurate or precise?
Set 1 7.21 7.25 7.18
Set 2 6.40 7.90 7.30
Set 3 6.45 6.52 6.48
Measuring
1. Def - All of the measured values plus one estimated place
2. Examples
6 cm 6.0 cm 6.01 cm
0.005 mm 0.0050 mm 0.00500 mm
1340 kg 1340. kg 1340.0 kg
Significant Figures
Measuring
Numbers with a DecimalHow many sig figs? Also, write in sci.
notation:3.44 cm60.001 cm430.0 cm0.0032 cm0.00320 cm
Measuring
1. Often poor measurements
2. Examples: “Not left”
18,500 kg 120 ft
Numbers without a Decimal
Measuring
How many sig figs? Also, write in scientific notation:
10,500 cm
240 cm
120,000 cm
4 cm
45 cm
Numbers without a Decimal
How many significant figures are in the following? Also, write the numbers in proper scientific notation.
1508 cm20.003 lb300 ft300.0 ft0.00705 m0.007050 m12501250.1250.0
Measuring
Round the following to three sig figs:
32.45
32.449
0.0067530
0.003904
11,980
Significant Figures
Round to four significant figures:
598,937
0.00053254
5.37286
0.39201
0.39205
How many significant figures?
0.00200 0.0020 100.7450 144.0 2008.40 X 1010 9.000 X 10-5
Round to three significant figures:
54.649999 1.456 X 10-4
300.847 8.605 X 107
200.490.000567320.0045282
Measuring
1. Math answers are only as good as the worst measurement.
2. Example:
Determining the area of a room:
6.9 m by 10.478 m
3. Round AFTER you do the math.
Significant Figures and Math
Measuring
Addition/Subtraction Rule - Keep the least number of decimal places.
Examples:
7.56 0.0327
0.375 – 0.00068
+ 14.2203
Significant Figures and Math
Measuring
Multiplication/Division Rule – Answer contains the least # of TOTAL significant figures
Examples23.4 X 32.25 =
Significant Figures and Math
Measuring
11.688 4.0 =
7 cm X 7 cm =
4.68 X 1016 9.1 X 10-5 =
Significant Figures and Math
1. Multiple Operations – Round when you change between add/sub and mult/div
2. Examples
(0.56 X 11.73) + 22.34 =
(6.5688) + 22.34 =
(6.6) + 22.34 = 28.9
(12.45 – 11.643) X 2.68 =
(0.807) X 2.68 =
0.81 X 2.68 = 2.1708 = 2.2
160 X 3.445 =
19.64 + 0.466 =
4.856 X 10102.0 X 102=
(16.44 2.33) + 22.3 =
(7.055793991) + 22.3
7.06 + 22.3 = 29.36 = 29.4
Measuring
160 X 3.445 = 550
19.64 + 0.466 = 20.11
4.856 X 10102.0 X 102 = 2.4 X 108
(16.44 2.33) + 22.3 = 29.4
Significant Figures and Math
Measuring
19.64 - 14.465 =
320 X 0.04550 =
3.1415 X 1011 X 8.47 X 10-7=
(12.7 X 10.43) + 23.8 =
0.00320 X 10-4 (write in proper sci. not.)
Warm-Up
Measuring
1. Also called “exact” numbers
2. Have an infinite number of significant figures
3. Counting numbers and values in definitions.
4. Examples:
23 students Diameter = 2r
1 km=1000m
5. NEVER use exact numbers for determining sf.
Absolute Numbers
Measuring
Absolute numbers or measured values?
Y= X3 37 apples
1 m = 100 cm 50 people
2.85 grams 400 people
1 cm = 10 mm
Measuring
If we divide 1.66 lbs of candy among 3 people, how much candy will each person get? (Ans: 0.553 lbs/person)
What is the diameter of a circle whose radius is 3.835 m?
(Ans: 7.670 m)
Absolute Numbers
Measuring
1. What is the diameter of a circle with a radius of 2.567 cm?
2. If we buy 1.84 pounds of coffee and divide it among three people, how much coffee will each person get?
3. How many centimeters is 7.565 meters?
4. How would you divide 12.35 kg of candy among eight children?
Measuring
Qualitative – data with no number
Quantitative – data with a number
Metric
Measuring
1. SI System – Le System International d’Unites
2. 1670 – Gabriel Mouton (French Vicar)
3. 1795 – Adopted by France
Metric
Measuring
Measuring
4. Base ten scale
1000 m = 1 km (kilo) 100 m = 1 hm (hecto) 10 m = 1 dam (deca)
1 m = 1 m 1 m = 10 dm (deci) 1 m = 100 cm(centi) 1 m = 1000 mm (milli)
Metric
Measuring
Measuring
Fundamental Units (MKS)Length meterMass kilogramsTime second
Derived UnitsVolume liter (dm3)Energy Joules (kg m2/s2)
Metric
Measuring
Factor Label method55 cm = ? m0.055 L = ? mL0.00456 km = ? cm550 cm2 = ? m2
25 miles/hr = ? m/s
Metric
a. 129 hrs Days
b. 0.468 mkm
c. 825 cm2 in2
d. 0.00230 L mL
e. 0.468 m mm
f. 1245 cm km
g. 55.0 mi/hr km/hr
h. 55.0 mi/hr m/min
129 hrs Days 5.38 days
0.468 mkm 0.000468
825 cm2 in2 128 in2
0.00230 L mL 2.30 mL
0.468 m mm 468 mm
1245 cm km 0.01245 km
55 mi/hr km/hr 88.5 km/hr
55 mi/hr m/min 1470 m/min
Measuring
1 km = 103 m1 hm = 102 m1 dam = 101 m1 m = 1 m1 dm = 10-1
1 cm = 10-2
1 mm = 10-3 m
Metric
Convert using powers of ten
50 cm = ? m
5 mm = ? m
65 km = ? m
23.3 mL = ? L
0.0047 mm = ? m
0.876 L = ? mL
1. Round to 3 sf: 0.0050460
2. Calculate using sf (10.345 – 8.23) X 54
3. 65.0 m/s =? miles/hr
4. 584 cm3 = ? in3
5. 234 cm = ? Feet
6. 3.00 X 108 m/s = miles/s
7. 45.0 L/s = gallons/min
(1.00 inch = 2.54 cm)
(1.609 km = 1.00 mile)
(1.000 gallon = 3.785 L)
1. 0.00505
2. 110
3. 145 miles/hr
4. 35.6 in3
5. 7.68 Feet
6. 3.00 X 108 m/s = 186 000 miles/s
7. 713 gallons/min
(1.00 inch = 2.54 cm)
(1.609 km = 1.00 mile)
(1.000 gallon = 3.785 L)
Temperature
Measuring
Absolute Zero
• All atomic and molecular motion stops
• Coldest possible temperature?
• Liquid Nitrogen = 77 K (-196 oC)
• Dry Ice = 216 K (-56.6 oC)
Temperature
Measuring
Measuring
Measuring
Planck Temperature = 1.417 x 1032 K
(temperature of the Big Bang)
Measuring
Conversion FormulasF = 1.8 (oC) + 32K = C + 273C = K – 273
Temperature
Measuring
Ex: 24 oC = oF48oF = oC177 K = oC
Temperature
Measuring
102 oF oC-10.0 oC oF25 oC K177 K oF310 oF K
Temperature
Measuring
102 oF 39oC-10.0 oC 14 oF25 oC 298 K177 K -141 oF310 oF 427 K
Temperature
Measuring
25 oC oF50 oF K310 K oC10 K oC-15 oC K
Temperature
Measuring
25 oC 77 oF50 oF 283 K(10 oC)310 K 37 oC10 K -263 oC-15 oC 258 K
Temperature
Measuring
Page 39
15 a) 0.77 b) 13.0 c) 32 d) 326
21 a) 5000 m b) 1400 ft2 c) 1.21 in2
d) 100 yd
23 a) 7 b) 12.7 c) 1.49
Measuring
Page 40 (40-42, 53, 55, 57, 60)
42 a) 6.8 X 106 6800 6.8
b) 786 0.786 7.68X10-4
c) 4452 4.452 4.452 X 10-3
53) 384,300km 55) 0.376 qt
57) 114 g 60) 109 yd (10.9 yd)
Measuring
23 a) 7
b) 12.7
c) 1.49
42 a) 6.8 X 106 6800 6.8
b) 786 0.786 7.68X10-4
c) 4452 4.452 4.452 X 10-3
Measuring
Measuring
Sig Figs Review WS1 a=4 b=3c=2 d=4e=3 f=6 g=2h=32a) 20. e) 6.27 b) 960 f) 417 c) 55.2 g) 2.7 d) 5800
Measuring
B2) 3ft=1yd,
10 dm = 1 m
1.00 gal = 3.78 L
2.20 lb = 1.00 kg
B3) 15.5 miles
B4) $2.16, 9.72 oz
B5) 366 cm
B6) $8.94
Measuring
29
4.23 X 105
4.338 X 102
2.0 X 10-3
8.8 X 102
8 X 10-5
8.2 X 107
7.5 X 1013
1.06 X 10-6
Measuring
39
1.58 X 10-10
2.29 X 1010
3.69 X 10-6
3.15 X 1012
Measuring3. Most precise = 26.202, most acc = 26.8
5. a) 2 b) 3 c) 3 d) 3
e) 4 f) 5 g) 2 h) 2
9. a) 120 b) 28 c) 38,000 d) 0.47
e) 56 f) 0.040 g) 1,600,000 h) 320
11.a) 0.667 b) 0.400 c) 0.625 d) 3.25
15. a) 0.77 b) 13.0 c) 32 d) 326
24. a) 120 cm2 b) 394 ft2 c) 2 cm d) 2.3 in
25. a) 5000 m b) 1400 ft2 d) 1.21 in2 d) 100 yd
27. a) 7 b) 12.7 c) 1.49
Measuring28.a) 1.57 X102 b)1.57X10-1 c) 3.00 X10-2
d) 4.0 X107 e) 3.49 X10-2 f) 3.2 X 104
g) 3.2 X1010 h) 7.71 X10-4 i) 2.34 X 103
29. a) 4.23 X105 b) 4.338 X102 c) 2.0 X10-3
d) 8.8 X102 e) 8 X10-5 f) 8.20 X107
g) 7.5 X1013 h) 1.06 X10-6
32. a) 0.000475 b) 6550 c) 0.00788
d) 489,000 e) 4.75 f) 3.4
33.a) 0.064 b) 8340 c) 220 d) 0.00342
Measuring34. a) 4.89 X10-4 b) 4.56 X10-5 c) 7.8X 103
d)5.71 X10-2 e) 4.975 X108 f) 3.0 X 10-2
35. a) 7.8X10-10 b) 7.2X10-1 c) 3.450X1019
d) 2.8X1010 e) 6.9X10-14 f) 2.3X103
39. a) 1.58 X10-10 b) 2.29 X1010
c) 3.69 X10-6 d) 3.15 X1012
43.a) 4.56 X1016 b) 5 X10-9
c) 1.7 X10-14 d) 1.26 X1012
MeasuringWrite in Sci Notation Write the expanded number
4 X 102 0.000 05
5 X 10-3 2 000 000 000
6 X 104 0.144
3.4 X 10-3 150 000 000 000
7.5 X 1012 0.000 000 244
6.457 X 10-2 300 000
5.6 X 10-5 0.00045
4.5 X 102 45 000
Calculate in Sci Nota)3 X 105
b)2 X 103
c)4.3 X 103
d)6 X 107
e)2.5 X 10-6
f)1.664 X10-3
g)3.0 X 104
h) 8 X 10-4
i)1.6 X 101
j)1.16 X 107
How many signif figures?
Calculate using SFa)15.2 m) 91.0b)20. n) 4.1c)6 o) 0.0075d)19.4e)15f)3.1g)1.23h)4.27i)0.0102j)50k)49l)49.0
Multiple operations & SFa)20.b)960c)55.2d)5800
Abs. # Calculationsa)303 cm3
b)756.3 cmc)1.544 kg/childd)0.65 me)5.134 cmf)25.6 mlg)553 cm2
h)0.613 kg/person
MeasuringMetric Conversions
a) 250 cm
b) 57 cm
c) 0.42 m
d) 420 mm
e) 46.7 m
f) 72,000 ml
g) 2.3 cm
h) 8.955 g
i) 8.68 X 10-6 kg
j) 0.654 g
k) 6,000 mL
l) 1.2 dm
m) 5.678292 km y) 0.0012 mL
n) 0.088 L z) 2.3 mL
o) 19 mL
p) 3.9 m
q) 0.0234 L
r) 45 mL
s) 1.2 cm
t) 0.072 g
u) 0.0862 km
v) 2470 cm
w)340 mL
x) 4.8 cm
MeasuringTemperature Conversions
a) 298 K
b) 25 oC
c) 226 K
d) -196 oC
e) 62.2 oC
f) 309 K
g) 263 K
h) 59 oC
i) 127 oC
j) 176 K
k) 5273 K
l) -271 oC
m) 371 K
n) 18.3 oC
o) 239 K
p) 33 oC
q) 256 K
62.
71. Longer, 10.9 yards
102.a) 310 K b) 408 K c) -68oC
d) -231 oF e) 311 K d) 248 K
lbs g kg
1.72 780. 0.780
2.17 985 0.985
16.0 7260 7.26
MeasuringComplete the following chart (1.00 inch = 2.54 cm)
How many Dekameters is 456 cm?
Convert 60oF to Celsius and Kelvin
inches cm m
4.75
824
0.537
MeasuringComplete the following chart (1.00 inch = 2.54 cm)
How many Dekameters is 456 cm? 0.456 dam
Convert 60.0oF to Celsius and Kelvin 15.6oC, 289K
inches cm m
4.75 12.1 0.121
324 824 8.24
21.1 53.7 0.537
MeasuringA 43 G 400 (4 X 102)
B 5.5 H 35
C 306.9 I 30
D 2.21 J 25
E 7.7 K 40
F 10.88 L 165