1. HONORS CHEMISTRY
August 3-4, 2011

2. Brain Teaser Quizlet Open Note Quizlet
Place Notes (Ch ) on your desk

3. Brain Teaser
What do you think will happen if I light the bubbles on fire?
Why?
Demo
Record Observations
Was your prediction correct?
Explain the science behind it

4. Agenda Brain Teaser Quizlet Measurement Terms Numbers Notes: Homework
SI Units
Intro to Significant Figures
Measurement and Significant Figures Mini Lab
Scientific Notation
Homework
Significant Figures Worksheet
Qualitative and Qunatitative Worksheet
Blubbenbacher’s Foods Lab Report  Due This Friday

5. Data Terms Quantitative Measurements Examples
Give results in a definite form, usually values
24L, 10 cm, 14 ºC

6. Data Terms Qualitative Measurements Examples
Give results in a descriptive, non-numeric form.
The beaker was warm.
The density was greater than that of water.

7. Data Terms Accuracy Examples
How close a measurement comes to the actual value of whatever is being measured
Water freezes at 0º C, and boils at 100º C. How close is the measurement to the values.

8. Data Terms Precision Examples Reproducibility of the measurement
9 out of 10 lab groups report the temperature of boiling water to be 95º C.
A basketball player shoots 20 free throws, 18 of which bounce off the right side of the rim.

9. Accuracy vs. Precision Target Practice
Accurate Precise Accurate & Precise

10. Percent error
Theoretical – Experimental x 100 = % error
Theoretical

11. Closure
Give and example of a qualitative and quantitative measurement.

12. SI Units (Le Systéme Internationale)
Units of measurement
SI Units (Le Systéme Internationale)
Scientists need to report data that can be reproduced by other scientists. They need standard units of measurement.
Base Units
A base unit is a defined unit in a system of measurement
There are seven base units in SI.
Refer to the handout on SI Units Le 12

13. Base Units Official definitions of the seven base units 13

14. Metric staircase 14

15. Significant Figures Significant Figures
Digits in a measurement that have meaning relative to the equipment being used

16. Significant Figures Place What is the increment on the equipment?
What you know for sure.

17. Significant Figures Digits with meaning Examples
Digits that can be known precisely plus a last digit that must be estimated.
Refer to Examples on the board: 1. 2. 3. 4

19. Scale Reading and Uncertainty
Uncertainty: Limit of precision of the reading (based on ability to guess the final digit).
Existed in measured quantities versus counted quantities
Refer to Example (2 rulers)
Addition and substraction(no. of sig. figs)
Division and Multiplication (no. of sig. figs) 19

20. Significant Figures: Mini Lab
Equipment to Evaluate
To what place (tenths, hundredths, etc.) can these measurement instruments accurately measure? What place is the estimation?
Triple beam balance
Analytical balance
Thermometer
Graduated cylinders
Beakers
Ruler
Burette

21. Significant Figures What do you notice?
Depends on type of equipment being used.
Depends on size of equipment used.

22. Significant Figures Raw Data Rules All digits 1-9 are significant.
How do you know how many sig figs?
All digits 1-9 are significant.
Zeros between significant digits are always significant.
Trailing 0’s are significant only if the number contains a decimal point
Zeros in the beginning of a number with a decimal point are not significant.
Zeros following a significant number with a decimal are significant.

23. Significant Figures Pacific to Atlantic Rule Examples
Pacific = Decimal Present
Start from the Pacific (left hand side), every digit beginning with the first 1-9 integer is significant
= 3 sig digits
= 6 sig digits
= 4 sig digits

24. Significant Figures Atlantic Rule to Pacific Examples
Atlantic = Decimal Absent
Start from the Atlantic (right hand side), every digit beginning with the first 1-9 integer is significant
= 5 sig digits
1000 = 1 sig digits

25. Practice
How many significant figures are in
400.0
4000
4004
0.004

26. Rally Rows How many significant figures are in 0.02 0.020 501 501.0
5000
5000.
5050
50300
5.0300

27. Summary Things to consider
What do significant figures tell you about the measurement equipment?
If you wanted to measure the mass of a whale, what scale would you want to use? Would it matter if you know its mass accurately to 1 gram?
If you wanted to measure the mass a grain of sand , what scale would you want to use? Would it matter if you know its mass accurately to 1 gram?

28. Instrument Measure
Need to make sure you are measuring and recording to the correct number of digits
Measure what you know for sure and then guess one more digit
Rulers
Draw a line on your paper and measure it to the correct number of digits
Beaker vs. graduated cylinder
Electronic balance vs. triple beam balance

29. Scientific Notation

30. Scientific Notation Scientific Notation Example
Shorthand way of expressing numbers that make them easier to work with
6.02 x 1023
2.34 x 105
3.78 x 10-3

31. Scientific Notation
Any Patterns?

32. Scientific Notation Rules Base number 1-9
Exponent = the number of times the decimal must be moved to bring the base number to 1-9.
Numbers greater than 1 have a positive exponent, numbers less than 1 a negative exponent

33. Scientific Notation
Examples
0.0025
1,750,000
2.5 x 10-3
1.75 x 106

34. Scientific Notation Problems 0.0000678 Express in Scientific Notation
0.5768

35. Scientific Notation Problems 1.567 x 10-3 Express in Standard Notation

36. Sig Figs in Scientific Notation
The numbers expressed in the scientific notation are significant
Examples:
5.02 x  x 104  3 S.F
The number of significant figures in a set of numbers will be the # of sig figs in the scientific notation.
 5 SF  x 101

37. Survivor Science
Convert the following to exponential notation or to ordinary notation
Tell me how many Sig Figs. 76
896745
8.9 x 103
3.45 x 10-1
0.222

38. x 10-3
5 million
8.00 x 104
953.6

39. Significant Figures in Calculations
What are Significant Digits?
Examples
Triple Beam Balance
Graduated Cylinder
All the certain digits plus the estimated digit in a measurement.
How many decimal places can we count

40. Significant Figures in Calculations
Exact Numbers
Examples
Infinite # of sig figs
Do not affect the number of significant digits in the final answer. They are not measurements!!
1000m = 1 km
12 in = 1 foot

41. Significant Figures in Calculations
Multiplication and Division
Example
The number with the smallest number of significant digits determines how many significant digits are allowed in the final answer.
Volume of a box
L x W x H
(3.05m)(2.10m)(0.75m)
2 sig figs
4.8m3

42. Significant Figures in Calculations
Example
Density of a penny
M = 2.53g V = 0.3mL
D = M / V
# significant figures allowed
D = 8g/mL

43. Significant Figures in Calculations
Addition and Subtraction
Example
The number of significant digits depends on the number with the largest uncertainty. (you may be using different scales)
Shoes g
Clothes g
Ring g
Glasses g
Total g

44. Significant Figures in Calculations
Example
What is the mass of a penny if, the weighing paper alone has a mass 0.67 g and weighing paper plus the penny has a mass of 3.2 g.
3.2 g
-0.67 g
2.5 g

45. Significant Figures in Calculations
Remember
A calculated number can only be as precise as the least precise measurement in the calculation.

46. Practice
Calculate each of the following to the correct number of significant figures. Include units on your answer.
(25 g/mol)(4.0 mol) =
(3.48 in)(1.28 in)(0.010 in) =
2.06 cm cm cm =
If the mass of a lead cube is g and it measures 2.51cm x 2.49 cm x 2.49 cm, what is the density of lead?

47. Practice
Calculate each of the following to the correct number of significant figures. Include units on your answer.
(25 g/mol)(4.0 mol) =1.0 x 102
(3.48 in)(1.28 in)(0.010 in) = .045 in3
2.06 cm cm cm = 3.9 cm
If the mass of a lead cube is g and it measures 2.51cm x 2.49 cm x 2.49 cm, what is the density of lead? 11.3 g/cm3

48. Rally rows Sig figs in Calculations
12 cm cm cm =
( g g) ÷ 8.01 mL=
17.3 cm x 6.2 cm cm2 =
m2  m =
What is the mass of Salt (NaCl) if the sodium has a mass of g and the Cl a mass of 35.5g?

49. Partner Challenge