1. International System of Units
Units provide a scale on which to represent the results of a measurement

3. Measurements of Length
- Fundamental unit is the meter
1 meter = inches

4. Measurements of Volume
- amount of 3-D space occupies by a substance
- fundamental unit is meter3 (m3)
1 cm3 = 1 ml

5. Items for measuring volume
Graduated cylinder- useful for dispensing approximate volumes
Buret- must be used when accuracy is important
Volumetric flask- contains a specified volume of liquid

7. Measuring Mass Weight- mass times gravity
Mass- the amount of matter in an object
- quantity of matter in an object
- fundamental unit is the kilogram

8. Measuring Density Density = mass/ volume
Derived unit- a unit obtained from more than one base unit.
Density- is a characteristic property that depends only on the composition of a substance, not on the size of the sample.
Pure substances have specific densities.
The density of a substance generally decreases as its temperature increases. Water is an important exception

10. Density Problems
What is the density of a block of marble that occupies 310cm3 and has a mass of 853g?
Diamond has a density of 3.26g/cm3. What is the mass of a diamond that has a volume of 0.350cm3?
What is the volume of a sample of liquid mercury that has a mass of 76.2g, given that the density of mercury is 13.6g/ml?

11. Measuring Specific Gravity
Specific Gravity- a comparison of the density of a reference substance. Water is a common reference substance.
Can be determined with a hydrometer
Specific Gravity = density of substance/ density of water
- Has no units

12. Measuring Temperature
Temperature- is related to the energy and motion of particles
Temperature scales
Celsius scale- based on the freezing and boiling points of water.
a. freezing point = 0 C
b. boiling point = 100 C

13. Kelvin scale- The zero point on the Kelvin scale is absolute zero
Kelvin scale- The zero point on the Kelvin scale is absolute zero. The theoretical point at which all motion stops. One degree Kelvin equals one degree celsius
K= C + 273
C= K - 273

15. Measuring Temperature
Practice Problems
Normal human body temperature is 37 C. What is your temperature in Kelvin?
The boiling point of the element Argon is 87 K. What is the boiling point of argon in C?

16. The Importance of measurement
Scientific Notation

17. Scientific notation 36,000 is 3.6 x 104
The exponent indicates how many times the coefficient 3.6 must be multiplied by 10 to equal the number 36,000.
Large numbers have positive exponents

18. Small numbers (less than one) have negative exponents.
is 8.1 x 10-3, the exponent -3 indicates that the coefficient 8.1 must be divided by 10 three times to equal

19. Multiplication and Division
To multiply numbers written in scientific notation, multiply the coefficients and add the exponents
(3.0 x 104) x (2.0 x 102)= 6.0 x 106

20. To divide numbers written in scientific notation, first divide the coefficient, then subtract the exponent in the dominator from the exponent in the numerator
3.0 x 104 / 2.0 x 102 = 1.5 x 102

21. Sample Problems Write each measurement in scientific notation
222 meters
2.22 x 102 meters
meters
7.285 x 105 meters
meters
5.4 x 10-4 meters

22. Multiplication and Division
(3.0 x 105) x (2.6 x 103)=
7.8 x 108
(2.8 x 103) / (1.4 x 10-2)=
2.0 x 105

23. Conversion Factors
Conversion factor- a ration of eqvivalent measurements, such as 100cm / 1m
The measurement in the numerator is equivalent to the measurement in the denominator.
Conversion factors are exact quantities. Therefore, they have an unlimited number of significant figures.