1. CHEMISTRY
July 31st, 2012

2. Brain Teaser: Dollar Bill2
What do think will happen if I dip a dollar bill in a 50% ethanol solution and light it on fire? Why?
Demo
Record Observations
Was your prediction correct?
Explain the science behind this

3. Agenda Brain Teaser Demo: Dollar Bill Lecture: Homework3
Brain Teaser
Demo: Dollar Bill
Lecture:
Introduction to Chemistry
SI Units and Base Units
Significant Figures
Homework
Intro to Measurement Worksheet

4. Unit 1 Objectives Introduction to Chemistry4
Define chemistry and matter
Units of measurement
SI Units
Base Units
Accuracy versus Precision
Uncertainty in Measurement
Significant Figures

5. Introduction to Chemistry5
Chemistry: The Central Science
Chemistry is the science that investigates and explains the structure and properties of matter.
Seeks to explain the submicroscopic events that lead to macroscopic observations

6. Branches of Chemistry Branch Area of Emphasis Examples6
Branch
Area of Emphasis
Examples
Organic chemistry
most carbon-containing chemicals
pharmaceuticals, plastics
Inorganic chemistry
in general, matter that does not contain carbon
minerals, metals and nonmetals, semi-conductors
Physical chemistry
the behavior and changes of matter and the related energy changes
reaction rates, reaction mechanisms
Analytical chemistry
components and composition of substances
food nutrients, quality control
Biochemistry
matter and processes of living organisms
metabolism, fermentation

7. SI Units (Le Systéme Internationale)
Units of measurement 7
Scientists need to report data that can be reproduced by other scientists. They need standard units of measurement.
Base Units Le
A base unit is a defined unit in a system of measurement
There are seven base units in SI.

8. Base Units 8 Official definitions of the seven base units

9. 9
Metric staircase

10. 10
SIGNIFICANT FIGURES

11. Significant Figures Significant Figures11
Significant Figures
Digits in a measurement that have meaning relative to the equipment being used

12. Significant Figures Place What is the increment on the equipment?12
Place
What is the increment on the equipment?
What you know for sure.

13. Significant Figures Digits with meaning13
Digits with meaning
Digits that can be known precisely plus a last digit that must be estimated.

14. 14

15. Ruler 15
What are the units?

16. Graduated Cylinder 16
ape/labdocs/catofp/measurea/volume/gradcyl/ gradcyl.htm
What are the units?

17. Significant Figures What do you notice?17
What do you notice?
Depends on type of equipment being used.
Depends on size of equipment used.

18. Significant Figures Raw Data Rules All digits 1-9 are significant.18
Raw Data Rules
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.

19. Significant Figures Pacific to Atlantic Rule Pacific = Decimal Present19
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

20. Significant Figures Atlantic Rule to Pacific Atlantic = Decimal Absent20
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

21. Practice 21
How many significant figures are in
400.0
4000
4004
0.004

22. Rally Rows How many significant figures are in 0.02 0.020 501 501.022
How many significant figures are in
0.02
0.020
501
501.0
5000
5000.
5050
50300
5.0300

23. Review Questions 23
Determine the number of significant figures in the following:
1.005
1000.
2002

24. Review Questions Determine the number of significant figures in:24
Determine the number of significant figures in:
72.3 g
60.5 g
6.20 g g
4320 g g
4.05 x 10^5 g
4500. g

25. Why do we use the metric system?25
Advantages
Simple to use
Easy to convert from one unit to another
Dimensional Analysis
Universal – used worldwide
By all scientists to communicate
By all industrialized nations
Except United States
U.S. loses billions of dollars in trade