THURSDAY, 19 TH SEPTEMBER 2013 Today in Chemistry Percent Composition Assignment Read pp. 320-355.
THURSDAY, SEPTEMBER 19, 2013
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Transcript of THURSDAY, SEPTEMBER 19, 2013
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THURSDAY, SEPTEMBER 19, 2013
LT: I can conduct safe lab experiments & use appropriate measurement tools correctly.
EW: List the base SI units for length, volume and mass.
Today: Metric System/Measurement Review Notes Finish Procedure
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The Metric System & Measurement
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BASIC UNITS
Mass: gram (g) Length: meter (m) Volume: Liter (L) or (l) Temperature Celsius (°C)
or Kelvin (K)
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CONVERTING Base 10 system
Move decimal right – X 10 move decimal left - ÷ 10
Converting bigger to smaller unit move decimal to the right; the equivalence is
bigger. ex. meters to centimeters
Converting smaller to bigger unit move decimal to the left; the equivalence is
smaller. ex. meters to kilometers
Let’s see how this works!
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THE CONVERSION LADDER
Basic
Unit
To convert to a smaller unit (going down the ladder) move the decimal to the right, or multiply
To convert to a bigger unit (going up the ladder) move the decimal to the left, or divide
Kilo-
1000 units
Hecto-
100 units
Deka-
10 units
deci-
0.1 units
centi-
0.01 units
milli-
0.001 units
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LET’S PRACTICE
Use the ladder method to find these equivalences:
1) 2 g = __________mg Remember, count the number of steps
you need to take on the ladder. If you are going up the ladder, move the decimal that many places to the left. If you are going down the ladder, move the decimal that many places to the right.
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LET’S TRY A FEW MORE…
2) 1000 ml = ____________ Kl 3) 500 m = _____________cm
Now for a few challenging ones 4) 325.2 cg = __________Dg 5) 0.9683 HL = _________dL
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CONVERTING BETWEEN SYSTEMS
Must know conversion factor (ratio showing how many units of one system are in 1 unit in the other system).
Handy conversion factors: 2.54 cm/1 in 1.609 km/1 mi 30.48 cm/1 ft 39.37 in/1 m
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EXAMPLE & PRACTICE!
EX. If 2.2 lbs equals 1 kg, how many kgs is 525 lbs?
Set up dimensional analysis:1. Write given measurement & X2. Set up conversion factor – put unit you are converting from in the denominator.3. Put unit you are converting to in numerator.4. Put 1 next to larger unit and how many equals one next to smaller unit.
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525 lbs X 1 kg 2.2 lbs5. Cancel units6. Do the math!
Try this!Bode’s beautiful tail is 2.7 ft. long. How many
centimeters is Bode’s tail? Remember there are 30.48 cm in 1 ft.
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SIGNIFICANT DIGITS
Meaningful digits in a measured quantity. Last digit may be uncertain (an estimate),
but it is still significant. When doing calculations with measurements
with different amounts of significant digits, your answer can only have as many digits as the least number you are working with. If your answer has more, you must round your answer.
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EXAMPLES
How many significant digits in 5.24? If I divide 5.24 by 3.8, how many significant
digits can I have in my answer? My calculator gave me the answer
1.378947368. What number should I report?
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USING MEASUREMENT EQUIPMENT
Distance – ruler or meter stick
Volume – graduated cylinder
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Mass – triple beam balance digital balance
Temperature – thermometer digital probe
Tutorial
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TUESDAY, SEPTEMBER 17, 2013
LT: I can conduct safe lab experiments and use appropriate measurement tools correctly.
EW: 1. 342.6 Kg = ? cg?2. 3.4 in. = ? cm? (2.54 cm = 1 in.)
Today:Measurement Lab
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WEDNESDAY, SEPTEMBER 18, 2013
LT: I can conduct safe lab experiments and use appropriate measurement tools correctly.
EW: If the triple beam balance can mass to the 10th of
a gram, how many decimal places should be in your mass calculation?
Today: Homework Quiz Measurement Lab – You will be assessed today
on participation, thoroughness and neatness of your lab work - +4 points possible
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CH. 1 HOMEWORK QUIZ
1. The English System of measurement is one system of measurement. What is the other system of measurement?
2. What is the prefix that indicates 1000 items or base units (it means 1000)?
3. What is an independent variable?
4. What is the responding (dependent) variable?
5. Convert 650 millimeters (mm) to meters (m)
6. Draw a picture of an xy graph. (label the x AND y axis)
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MEASUREMENT LAB
First lab in Composition Lab Note Book! First page – Table of Contents Third page – Title: Measurement Lab
Directions: You will visit 6 stations. Provide a clear title in
your book for the work you do at each station! Follow the directions posted at each station,
doing the written work in your Comp Book. Station 7, if time allows. Finish by answering Focus Questions
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MEASURING FOCUS QUESTIONS
When measuring, for which digit do scientists expect uncertainty? Explain why it is still significant and should be reported.
Why would you zero a balance before each use?
Why would you zero the weighing dish before placing the substance in it?
When you used 2 different technologies to measure mass or temperature, did the measurements match exactly? Why might they have been different?
List and explain 3 safety rules you followed in this lab.