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

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

Measurements of Volume  Volume - amount of 3-D space occupies by a substance - amount of 3-D space occupies by a substance - fundamental unit is meter 3 (m 3 ) - fundamental unit is meter 3 (m 3 ) 1 cm 3 = 1 ml 1 cm 3 = 1 ml

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

Measuring Mass -Weight- mass times gravity -Mass- 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 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

Density Problems 1.What is the density of a block of marble that occupies 310cm 3 and has a mass of 853g? 2.Diamond has a density of 3.26g/cm 3. What is the mass of a diamond that has a volume of 0.350cm 3 ? 3.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?

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

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. Celsius scale- based on the freezing and boiling points of water. a. freezing point = 0 C a. freezing point = 0 C b. boiling point = 100 C b. boiling point = 100 C

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 K= C C= K C= K - 273

Measuring Temperature Practice Problems 1.Normal human body temperature is 37 C. What is your temperature in Kelvin? 2.The boiling point of the element Argon is 87 K. What is the boiling point of argon in C?

The Importance of measurement Scientific Notation

Scientific notation 36,000 is 3.6 x ,000 is 3.6 x 10 4 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

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

Multiplication and Division To multiply numbers written in scientific notation, multiply the coefficients and add the exponents (3.0 x 10 4 ) x (2.0 x 10 2 )= 6.0 x 10 6

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 10 4 / 2.0 x 10 2 = 1.5 x 10 2

Sample Problems Write each measurement in scientific notation a.222 meters 2.22 x 10 2 meters 2.22 x 10 2 meters b meters x 10 5 meters x 10 5 meters c meters 5.4 x meters 5.4 x meters

Multiplication and Division a.(3.0 x 10 5 ) x (2.6 x 10 3 )= 7.8 x x 10 8 b.(2.8 x 10 3 ) / (1.4 x )= 2.0 x x 10 5

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.