Transcript Chapter 2: Analyzing Data

Chapter 2
Analyzing Data
• Make a new section in your table
of contents – Chapter 2:
Analyzing Data
• Do not forget page numbers
• Beginning, ending, and
throughout book
• Go to first blank page and write
chapter 2 across it
Bellwork
• Chapter Essential Question:
• How do scientists analyze data in order to
determine how matter interacts?
• Lesson Essential Questions:
• Why do chemists use an international system
of measurement?
• Why do measurements contain uncertainties
and how can we counteract these?
Next Page – Copy Down
• Essential questions from
Chapters 1, 2, and 3 will be
due on Exam day.
Reminder!!!
• Four column definition activity
• Word, Definition, Your Definition, Picture/Example
• Words
•
•
•
•
•
•
Accuracy
Density
Percent Error
Precision
Scientific Notation
Significant Figures
• Conversions
• Base Units
• SI units
Chapter 2 Word Study
Guide
•Read Chapter 2
• Complete the Chapter 2 Outline
• Do not just DEFINE words
• Give complete explanations
Bellwork/Homework
• How many Styrofoam cups equal Mrs.
Stewart’s height???
GO!!!
Problem
© 2013, Robert Ayton. All rights reserved. www.mrayton.com
• What information did you need to find out
in yesterday’s launch lab?
• What mattered?
Bellwork
• What mattered???
• Lip
• Height of one Cup (the final cup)
• How Tall is Mrs. Stewart.
y = mx + b
1 Cup Height
My Height
Lip
# of Cups
Styrofoam Cup Lab
© 2013, Robert Ayton. All rights reserved. www.mrayton.com
• What was the benefits of this lab?
•
•
•
•
•
Measuring
Forming Scientific Questions
Data Collections
Communication
Connecting to Other Subject Areas
Styrofoam Cup Lab
© 2013, Robert Ayton. All rights reserved. www.mrayton.com
• In your journal, answer the
following questions
• What are the base units for Time, Length, Mass,
Temperature, and Volume.
• Discuss what density is, and how do you measure it.
• How do you convert between two different units.
Metric Units
• 2.34g  cg
• 456 dL  hL
Lets Complete a couple
examples
•
•
•
•
•
0.026L  mL
832ks  hs
34,600 m  km
398.6dg  dag
WHEN I TELL YOU!!!! Get with your shoulder partner
and discuss your answers.
Convert the following
Numbers
• Identify the equations used to convert between °C and K.
As well as between °C and °F.
• Convert the following
• 365 K  °C
• 32°F  °C
Journal
• When a piece of aluminum with a
density of 2.7 g/mL is placed in a 25mL graduated cylinder that contains
10.5 mL of water, the water level rises
to 13.5 mL. What is the mass of the
aluminum?
Density
• Complete problems 1-3 on
page 38
• Get with your shoulder partner and discuss
your answers as well as the process.
Practice Problems
• Is used to express any number as a number between 1 and
10 multiplied by 10 raised to a power.
Scientific Notation
• Page 41 #’s 11 and 12
• Get with your shoulder partner and discuss your answers.
• We will go over them as a class!
Practice Using Scientific
Notation
• If a piece of metal has a density of 6.23 g/cm3 and a mass of
12.4 g, what is the volume of the metal?
• Convert the following units
• 0.36 L  mL
• 32300 dm  km
• 43.6 hg  cg
• Put in Scientific Notation
• 0.00034 km
• 63000000 mg
• Write in standard notation
• 3.6 x 105
• 6.34 x 10-7
Understanding Check
• Step 1: Notice if the powers of 10 are the same
• If they are bring straight down and add or subtract front
numbers like normal
• If not, move to step 2
• Step 2: Identify the highest power of 10 and keep it the
same
• Step 3: Make the power of 10 the same as the higher
number by moving the decimal left the correct number of
spaces.
• Step 4: bring the power of 10 down, and then add or
subtract front numbers like normal
Adding and Subtracting
Scientific Notation
Adding
Subtracting
1. 2.3 x 103
+9.8 x 102
1. 7.3 x 104
- 2.6 x 106
--------------------------
--------------------------
2. 3.6 x 105
+ 4.2 x 106
2. 8.1 x 102
- 5.3 x 104
---------------------------
---------------------------
Adding and Subtracting
Examples
• MOVE DECIMAL TO MAKE THE POWER OF 10
THE SAME!!!
• Go with the highest exponent
• Practice Problems pg 42
• 13cd and 14cd
Bellwork: Adding and
Subtracting Scientific
Notation
• Turn in weekend homework problems
• Review adding and subtracting scientific notation with
your shoulder partner.
• (8.6 x 105) – (2.2 x 103)
• (7.2 x 10-1 kg) + (6.8 x 10-1 g) in grams
Bellwork
• Step 1: Identify whether you are multiplying or dividing
• Step 2: if multiplying, add exponents. If dividing,
subtract exponents.
• Step 3: Multiply or divide front numbers like normal
• Step 4: Make sure your final answer is in correct
scientific notation.
Multiplying and dividing
scientific Notation
Multiplying
Dividing
1. 2.3 x 105
x1.6 x 103
1. 9.72 x 108
/ 1.3 x 105
--------------------------
-------------------------
2. 6.7 x 102
x 5.2 x 103
2. 5.2 x 104
/ 3.6 x 108
--------------------------
------------------------
Multiplying and Dividing
Examples
• IF MULTIPLYING, ADD powers of 10.
• If DIVIDING, SUBTRACT powers of 10.
• Practice Problems pg 43
• 15bd and 16bd
Multiplying and Dividing
Scientific Notation
• Complete the following problems
•
•
•
•
(2.3 x 102) – (9.2 x 103)
(3.4 x 10-3 kg) + (6.8 x 10-1 kg)
(2.35 x 103) x (6.00 x 105)
(4.3 x 102)/(7.38 x 104)
Review
Accuracy
Data
• The true value is .5g
• The students
experimental values are:
•
•
•
•
Accuracy
.51g
.49g
.5g
.52g
Precision
Data
• The true value is .5g
• The students
experimental values are:
•
•
•
•
Precision
.8g
.81g
.79g
.79g
Accuracy vs. Precision
• Three Key Components
1. Accepted Value
1.
A value determined correct through mathematical calculations
2. Experimental Value
1.
A value determined through experimentation (your value)
3. Error
1.
How far the experimental value is from the accepted value.
Error
• Joshua uses his thermometer and finds the boiling point
of ethyl alcohol to be 75oC. He looks in a reference book
and finds that the actual boiling point of ethyl alcohol is
80oC.
• What is his error?
Example:
Error=Experimental value-accepted value
• Equation on page 48
• Percent error = ( error /accepted value) x 100
• Percent error expresses error as a percentage of the
accepted value
• Most commonly used error expression
• Must have: error and accepted value to calculate
• Example
• The density of water at 4oC is known to be 1.00 g/mL.
Kayla experimentally found the density of water to be 1.075
g/mL. What is her percent error?
Percent Error
• You may work with your shoulder partner
• Examples page 49
• 32-34
Practice Problems
• Rules
• Every NON ZERO digit is significant
• Zeros to the LEFT of the first non-zero digit is NEVER significant
• Zeros in the MIDDLE of two non-zero digits are ALWAYS
significant
• Zeros to the Right of the LAST non-zero digit are SOMETIMES
significant
• If you see a decimal = YES!
• If you DO NOT see a decimal = NO!
• Counting numbers and ratios/conversions have an infinite number
of significant figures.
Copy: Significant Figures
• Examples:
• 1234 = 4 significant figures
• 2.34 = 3 significant figures
• 14,567 = 5 significant figures
• How many significant figures in the following numbers?
• 54
• 3.4568
Rule 1: Every NON ZERO
digit is significant
• Steps
• Find 1st non-zero digit
• Cross out all zeros in front of it
• Examples
• 0.00023 = 2 significant figures
• 0.6789 = 4 significant figures
• Practice
• 0.344
• 0.000007
Rule 2: Zeros to the LEFT of the first
non-zero digit is NEVER significant
• This means all zeros surrounded by non-zero digits are
ALWAYS counted as significant.
• Example:
• 43201 = 5 significant figures
• 2001 = 4 significant figures
• 403050708 = 9 significant figures
• Practice Problems
• 600045
• 902
Rule 3: Zeros in the MIDDLE of two nonzero digits are ALWAYS significant
• Steps
• Identify last non-zero digit
• If there are zeros to the right, then look for a decimal somewhere
in the number
• If you see a decimal = YES!!
• If no decimal = NO!
• Example
• 3.4000 = 5 significant figures (decimal)
• 34000 = 2 significant figures (no decimal)
• Practice Problems
• 654.000
• 3340.
• 200
Rule 4: Zeros to the Right of the LAST nonzero digit are SOMETIMES significant
• If you are counting an object there are infinite significant
figures
• Ex: 8 computers = infinite significant figures
• Ex: 26 students = infinite significant figures
• If you have a conversion or ratio the are infinite
significant figures
• Ex: 1000mm = 1m = infinite
• Ex: 12 eggs = 1 dz
Rule 5: Counting numbers and
ratios/conversions have an infinite number of
significant figures.
•
•
•
•
All non zeros are significant
Left zeros = never
Middle Zeros = Always
Right Zeros = Only if there is a decimal
Key Points
• Determine the number of significant figures in the
following measured values
•
•
•
•
•
0.0546
298.206
102000
0.003145
7.847000
Examples
• Pg 51 #’s 35-37
Practice Problems
• Convert
• 40g  mg
• .00034 km  cm
• 36°C  K
• Scientific Notation
• 0.0000067
• (2.4 x 103) + (3.6 x 102)
• (3.5 x 106) / (1.7 x 108)
• Accuracy vs. Precision
• Explain the difference between accuracy and precision
• Error
• A student completed their experiment and wanted to calculate
their percent error. The teacher explained that the precipitate
should have had a mass of 4.8g. The student calculated a mass of
3.4g. Help the student calculate their percent error!
Bellwork
• Round to the lowest amount of decimal
• Examples
• 3.4 + .28 + 35 =
• 4.6 x 103
- 3.9 x 102
----------------------------
• Practice Problems: Pg 53 #’s 40 and 41
Adding and Subtracting
Sig Fig’s
places
• Chemistry Handbook
•Page 18 #’s 24a-d and
25 ab
•Separate sheet of paper
H.W. Practice problems
• Round to the lowest number of significant
figures
• Examples
• 1.3 x 0.2 x 3.26 =
• 3.46 x 103
/ .60 x 102
---------------------------
• Practice Problems: 42ab, 43cd, 44 (pg 54)
Multiplying and Dividing
Sig Figs
• Write down all the rules for SIGNIFICANT
FIGURES!
• How do you round when you add and subtract?
• How do you round when you multiply and
divide?
Journal Entry – 5 min
1. With your shoulder partner, complete
the worksheet in your COMPOSITION
BOOK.
2. When told to do so, you will get with
another partner and come up with a
consensus on a separate sheet of paper for
all answers
3. Turn in consensus paper for a GRADE
Significant Figures Worksheet
• TURN IN EQs RIGHT NOW!!!!
• Get with your shoulder partner and continue working on
the worksheet
• You have about 15 minutes
• Test you need
• Two sheets of paper
• Pencil
• Calculator
Bellwork
• 32 (pg49), 35ac,36ac, 37 (pg
51), 38ab, 39ab, 40, 41
(pg53),42ab,43ab,44 (pg54)
Complete Practice
Problems (Shoulder
Partner)