International System of International System of UnitsUnits

Units provide a scale on which to Units provide a scale on which to represent the results of a measurementrepresent the results of a measurement

Measurements of LengthMeasurements of Length

LengthLength

- Fundamental unit is the meter- Fundamental unit is the meter

1 meter = 39.37 inches1 meter = 39.37 inches

Measurements of VolumeMeasurements of Volume

VolumeVolume

- amount of 3-D space occupies by a - amount of 3-D space occupies by a substancesubstance

- fundamental unit is meter- fundamental unit is meter3 3 (m(m33))

1 cm1 cm33 = 1 ml = 1 ml

Items for measuring Items for measuring volumevolume

Graduated cylinder- useful for dispensing Graduated cylinder- useful for dispensing approximate volumesapproximate volumes

Buret- must be used when accuracy is Buret- must be used when accuracy is importantimportant

Volumetric flask- contains a specified Volumetric flask- contains a specified volume of liquidvolume of liquid

Measuring MassMeasuring Mass

- Weight- mass times gravityWeight- mass times gravity

- Mass- the amount of matter in an objectMass- the amount of matter in an object

- quantity of matter in an object- quantity of matter in an object

- fundamental unit is the kilogram- fundamental unit is the kilogram

Measuring DensityMeasuring Density

Density = mass/ volumeDensity = mass/ volumeDerived unit- a unit obtained from more than one base Derived unit- a unit obtained from more than one base

unit.unit.Density- is a characteristic property that depends only on Density- is a characteristic property that depends only on

the composition of a substance, not on the size of the the composition of a substance, not on the size of the sample.sample.

Pure substances have specific densities.Pure substances have specific densities.

The density of a substance generally decreases as its The density of a substance generally decreases as its temperature increases. Water is an important temperature increases. Water is an important exceptionexception

Density ProblemsDensity Problems

1.1. What is the density of a block of marble that What is the density of a block of marble that occupies 310cmoccupies 310cm33 and has a mass of 853g? and has a mass of 853g?

2.2. Diamond has a density of 3.26g/cmDiamond has a density of 3.26g/cm33. What is . What is the mass of a diamond that has a volume of the mass of a diamond that has a volume of 0.350cm0.350cm33??

3.3. What is the volume of a sample of liquid What is the volume of a sample of liquid mercury that has a mass of 76.2g, given that mercury that has a mass of 76.2g, given that the density of mercury is 13.6g/ml?the density of mercury is 13.6g/ml?

Measuring Specific Measuring Specific GravityGravity

Specific Gravity- a comparison of the Specific Gravity- a comparison of the density of a reference substance. Water density of a reference substance. Water is a common reference substance.is a common reference substance.

- Can be determined with a hydrometerCan be determined with a hydrometer

Specific Gravity = density of substance/ Specific Gravity = density of substance/ density of waterdensity of water

- Has no units- Has no units

Measuring TemperatureMeasuring Temperature

Temperature- is related to the energy and Temperature- is related to the energy and motion of particlesmotion of particles

Temperature scalesTemperature scales

Celsius scale- based on the freezing and Celsius scale- based on the freezing and boiling points of water.boiling points of water.

a. freezing point = 0 Ca. freezing point = 0 C

b. boiling point = 100 Cb. boiling point = 100 C

Kelvin scale- The zero point on the Kelvin Kelvin scale- The zero point on the Kelvin scale is absolute zero. The theoretical scale is absolute zero. The theoretical point at which all motion stops. One point at which all motion stops. One degree Kelvin equals one degree celsiusdegree Kelvin equals one degree celsius

K= C + 273K= C + 273

C= K - 273C= K - 273

Measuring TemperatureMeasuring Temperature

Practice ProblemsPractice Problems

1.1. Normal human body temperature is 37 Normal human body temperature is 37 C. What is your temperature in Kelvin?C. What is your temperature in Kelvin?

2.2. The boiling point of the element Argon The boiling point of the element Argon is 87 K. What is the boiling point of is 87 K. What is the boiling point of argon in C?argon in C?

The Importance of The Importance of measurementmeasurementScientific NotationScientific Notation

Scientific notationScientific notation

36,000 is 3.6 x 1036,000 is 3.6 x 1044

The exponent indicates how many times The exponent indicates how many times the coefficient 3.6 must be multiplied by the coefficient 3.6 must be multiplied by 10 to equal the number 36,000.10 to equal the number 36,000.

Large numbers have positive exponentsLarge numbers have positive exponents

Small numbers (less than one) have Small numbers (less than one) have negative exponents.negative exponents.

0.0081 0.0081 is is 8.1 x 108.1 x 10-3-3, the exponent -3 , the exponent -3 indicates that the coefficient 8.1 must be indicates that the coefficient 8.1 must be divided by 10 three times to equal 0.0081divided by 10 three times to equal 0.0081

Multiplication and Multiplication and DivisionDivision

To To multiplymultiply numbers written in scientific numbers written in scientific notation, notation, multiplymultiply the coefficients and the coefficients and addadd the exponentsthe exponents

(3.0 x 10(3.0 x 1044) x (2.0 x 10) x (2.0 x 1022)= 6.0 x 10)= 6.0 x 1066

To To dividedivide numbers written in scientific numbers written in scientific notation, first notation, first dividedivide the coefficient, then the coefficient, then subtractsubtract the exponent in the dominator the exponent in the dominator from the exponent in the numeratorfrom the exponent in the numerator

3.0 x 103.0 x 1044 / 2.0 x 10 / 2.0 x 1022 = 1.5 x 10 = 1.5 x 1022

Sample ProblemsSample Problems

Write each measurement in scientific Write each measurement in scientific notationnotation

a.a. 222 meters222 meters 2.22 x 102.22 x 1022 meters metersb.b. 728500 meters728500 meters 7.285 x 107.285 x 1055 meters metersc.c. 0.00054 meters0.00054 meters 5.4 x 105.4 x 10-4-4 meters meters

Multiplication and DivisionMultiplication and Division

a.a. (3.0 x 10(3.0 x 1055) x (2.6 x 10) x (2.6 x 1033)=)=

7.8 x 107.8 x 1088

b.b. (2.8 x 10(2.8 x 1033) / (1.4 x 10) / (1.4 x 10-2-2)=)=

2.0 x 102.0 x 1055

Conversion FactorsConversion Factors

Conversion factor- a ration of eqvivalent Conversion factor- a ration of eqvivalent measurements, such as 100cm / 1m measurements, such as 100cm / 1m

The measurement in the numerator is The measurement in the numerator is equivalent to the measurement in the equivalent to the measurement in the denominator.denominator.

Conversion factors are exact quantities. Conversion factors are exact quantities. Therefore, Therefore, they have an unlimited they have an unlimited number of significant figures.number of significant figures.