1. Scientific Method & Measurement Unit
Unit EQ: Why is it important to know how to use chemistry skills?

2. Identifying Laboratory Equipment
EQ: Why is it important to know how to use different types of laboratory equipment?

3. Identifying Laboratory Equipment Notes
Notes at stations
Move from station to station to complete notes
No more than 2 students at a station at a time

4. Reading Scientific Instruments
EQ: How do significant figures relate to measurements in chemistry?

5. Reading a Meterstick or Metric Ruler
Each number represents a centimeter (cm)
Each small line represents a millimeter (mm)
Always estimate to one digit beyond the smallest line marker

6. Reading a Meterstick or Metric Ruler
0.00 cm
1.49 cm
2.26 cm
3.20 cm

7. Reading a Graduated Cylinder
Meniscus – curved surface of water
caused by adhesion of water to glass
When reading a meniscus,
Stoop so that the water is at your eye level
Read the volume from the bottom of the meniscus

8. Reading a Graduated Cylinder

9. Significant Figures
Contain all certain digits and one estimated (uncertain) digit
Example: 36.4 mL
The 3 and the 6 are certain; there is no doubt there are at least 36 mL
The 4 is uncertain; this digit is estimated, but tells us there is close to half of another mL

10. Metric Units and Prefixes
EQ: Why is the metric system the most useful system for measurements in chemistry?

11. Why the Metric System?
The metric, or SI system of measurement is based on multiples of 10.
Devised in 18th century France by Lavoisier
Standard system to be used in all countries
Sizes in other systems differed, causing disputes among merchants
Based on properties of water
On liter of water has a mass of 1 kilogram and a volume of 1 cubic decimeter.

12. Base Units in the SI System
Length = meter (m)
Mass = gram (g)
Volume = liter (L)
Prefix tells you how much larger or smaller the unit is than the base

13. Writing Abbreviations in the Metric System
Write abbreviation for prefix
Write abbreviation for base
Deciliters = dL
Millimeter = mm
Micrograms = μg
Megagrams = Mg
Hectometers = hm
Nanoliters - nL

14. Metric Conversions Find the starting unit
Count the steps to the ending unit
Move the decimal the same number of spaces in the same direction

15. Metric Conversions Convert 65 meters to centimeters
Starting = meters (base)
Ending = centi-
Move decimal 2 places to the right
65 m = 6500 cm

16. Metric Conversions Convert 130 dekagrams to decigrams Starting = deka-
Ending = deci-
Move decimal 2 places to the right
130 dag = dg

17. Metric Conversions Convert 17 hectometers to kilometers
Starting = hecto-
Ending = kilo-
Move decimal 1 place to the left
17 hm = 1.7 km

18. Metric Conversions Convert 4.58 mL to L Starting = milli-
Ending = base
Move decimal 3 places to the left
4.58 mL = L

19. Metric Conversions Convert 4.998 mg to kg Starting = milli-
Ending = kilo-
Move decimal 6 places to the left
4.998 mg = kg

20. Metric Conversions Convert 34 cL to hL Starting = centi-
Ending = hecto-
Move decimal 4 places to the left
34 cL = hL

21. Precision and Accuracy
EQ: Compare and contrast precision and accuracy.

22. Accuracy How close a measurement or calculation is to the actual value
In lab, measurements are accurate if they have less than 10% error.

23. Percent Error Determines the accuracy of lab data
Don’t forget the absolute value! Percent error is never negative.
Theoretical = what you should have gotten
Actual = what you got

24. Precision How close together two measurements are Or
The number of significant digits in a measurement

25. Precision vs. Accuracy