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Chapter 2

Chapter 2. Section 2. Section 2 Objectives. Be able to define: quantity, measurement, standard, length, mass, weight, derived unit, volume, density, conversion factor. Be able to state the units of mass, length, temperature, and time in the SI system

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Chapter 2

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  1. Chapter 2 Section 2

  2. Section 2 Objectives • Be able to define: quantity, measurement, standard, length, mass, weight, derived unit, volume, density, conversion factor. • Be able to state the units of mass, length, temperature, and time in the SI system • Be able to explain the difference between mass and weight.

  3. Section 2 Objectives • Be able to state the meaning of common prefixes used in the SI system (Deka-, Hecto-, Kilo-, Mega-, Giga-, deci-, centi-, milli-, micro-, nano-. • Be able to convert units within the SI system.

  4. Section 2: Units of Measure • Measurements are quantitative information. • Measurements _______________ quantities. • A quantity is something that has __________________, __________, or ________________. • A quantity is not the same as a measurement. • Example: A teaspoon is a unit of measurement for volume (a quantity) • Nearly every measurement is a number plus a ___________.

  5. Section 2: Units of Measure • Measurements are quantitative information. • Measurements representquantities. • A quantity is something that has __________________, __________, or ________________. • A quantity is not the same as a measurement. • Example: A teaspoon is a unit of measurement for volume (a quantity) • Nearly every measurement is a number plus a ___________.

  6. Section 2: Units of Measure • Measurements are quantitative information. • Measurements representquantities. • A quantity is something that has magnitude, size, or amount. • A quantity is NOT the same as a measurement. • Example: A teaspoon is a unit of measurement for volume (a quantity) • Nearly every measurement is a number plus a ___________.

  7. Section 2: Units of Measure • Measurements are quantitative information. • Measurements representquantities. • A quantity is something that has magnitude, size, or amount. • A quantity is NOT the same as a measurement. • Example: A teaspoon is a unit of measurement for volume (a quantity) • Nearly every measurement is a number plus a unit.

  8. Section 2: Units of Measure • Scientists all over the world have agreed on a single measurement system, ____________. • These units are defined in terms of standards of ______________________________. • International organizations monitor the defining process, such as the ____________________ ________________ ___ __________ ____ ____________________ in the United States.

  9. Section 2: Units of Measure • Scientists all over the world have agreed on a single measurement system, SI. • These units are defined in terms of standards of ______________________________. • International organizations monitor the defining process, such as the ____________________ ________________ ___ __________ ____ ____________________ in the United States.

  10. Section 2: Units of Measure • Scientists all over the world have agreed on a single measurement system, SI. • These units are defined in terms of standards of measurement. • International organizations monitor the defining process, such as the ____________________ ________________ ___ __________ ____ ____________________ in the United States.

  11. Section 2: Units of Measure • Scientists all over the world have agreed on a single measurement system, SI. • These units are defined in terms of standards of measurement. • International organizations monitor the defining process, such as the National Institute of Standards and Technology (NIST) in the United States.

  12. Section 2: Units of Measure For example, the number seventy five thousand is written ___________________ instead of ____________________________ because the comma is used in other countries to represent a decimal point

  13. Section 2: Units of Measure For example, the number seventy five thousand is written 75 000 instead of 75,000because the comma is used in other countries to represent a decimal point

  14. SI System • The SI system defines 7 base units for 1. length, 2. mass, 3. time, 4. temperature, 5. amount of a substance

  15. SI Base Units Quantity Quantity Symbol Unit name Unit abbreviation 1. Length l Meter m 2. MassmKilogramkg 3. Time t Second s 4. Temperature T Kelvin K 5. Amt of Subst. n Mole mol

  16. SI Base Units: Mass • Mass is the measure of the ______________ ____ ________________. • The ___________, g, is 1/1000 of a kilogram and is more useful for measuring masses of small objects such as flasks and beakers. • For even smaller objects, such as tiny quantities of chemicals (think: medicines or vitamins!), the _____________ or ____ is used.

  17. SI Base Units: Mass • Mass is the measure of the quantity of matter. • The gram, g, is 1/1000 of a kilogram and is more useful for measuring masses of small objects such as flasks and beakers. • For even smaller objects, such as tiny quantities of chemicals (think: medicines or vitamins!), the milligram or mgis used. • 1 milligram = 1/1000 of a gram

  18. SI Base Units: Mass • The measure of the gravitational pull on matter (gravity) is _______________. • Mass does not depend on ____________. • As the force of Earths’ gravity on an object increases, the object’s weight _____________________. • The weight of an object on the moon is about ___________ of its weight on Earth.

  19. SI Base Units: Mass • The measure of the gravitational pull on matter (gravity) is weight. • Mass does not depend on gravity. • As the force of Earths’ gravity on an object increases, the object’s weight _____________________. • The weight of an object on the moon is about ___________ of its weight on Earth.

  20. SI Base Units: Mass • The measure of the gravitational pull on matter (gravity) is weight. • Mass does not depend on gravity. • As the force of Earths’ gravity on an object increases, the object’s weight increases. • The weight of an object on the moon is about one-sixth (1/6) of its weight on Earth.

  21. SI Base Units: Length • The SI standard unit for length is the ______________. • To express longer distances, the __________________, ___ is used. • To express short distances, the _____________, _____ is used. (add to notes) • One _____________ is 1000 meters.

  22. SI Base Units: Length • The SI standard unit for length is the meter. • To express longer distances, the kilometer, kmis used. • To express short distances, the _____________, _____ is used. (add to notes) • One _____________ is 1000 meters.

  23. SI Base Units: Length • The SI standard unit for length is the meter. • To express longer distances, the kilometer, kmis used. • To express short distances, the centimeter, cm is used. (add to notes) • One kilometeris 1000 meters.

  24. m m2 m Derived SI Units • Combination of SI base units form ________ ______. • For example, area, is ________ x ________.

  25. m m2 m Derived SI Units • Combination of SI base units form derived units. • For example, area, is ________ x ________.

  26. m m2 m Derived SI Units • Combination of SI base units form derived units. • For example, area, is length x width. Area = L x W Area = m x m Area = m2

  27. Derived SI Units Quantity Symbol Unit name Unit abbrev. Derivation 1. Area A Square Meter m2lengthxwidth 2. Volume V Cubic Meter m3 l xwx height 3. Density D Kilograms per cubic meter kg/ m3 mass/volume 4. Molar Mass M Kilograms per mole kg/molm/amt. of sub. 5. Molar Volume Vmcubic meters per mole m3/molvolume/n 6. Energy E Joule J force x length

  28. Derived SI Units - Volume • The amount of space occupied by an object is ____________, and the derived SI unit is ___________ _________. • This amount is equal to the volumne of a cube whose edges are each ____ ___ long. • But in a chemistry laboratory, we need a smaller unit, so we often use _________________ ______________, ______.

  29. Derived SI Units - Volume • The amount of space occupied by an object is volume, and the derived SI unit is cubic meters, m3. • This amount is equal to the volume of a cube whose edges are each ____ ___ long. • But in a chemistry laboratory, we need a smaller unit, so we often use _________________ ______________, ______.

  30. Derived SI Units - Volume • The amount of space occupied by an object is volume, and the derived SI unit is cubic meters, m3. • This amount is equal to the volume of a cube whose edges are each 1 m long. • But in a chemistry laboratory, we need a smaller unit, so we often use cubic centimeter, cm3.

  31. Derived SI Units - Volume (1 m3) x (100 cm/1m)x (100 cm/1 m) x (100 cm/1 m)= 1 000 000 cm3

  32. Derived SI Units - Volume • When chemists measure the volumes of liquid and gases, they often use a non-SI unit called the ________. • **Another non-SI unit, the ________________, or ___, is used for smaller volumes. There are _____________ mL in 1 L. • Because there are also __________ cm3 in a liter, the 2 units, ____________ and __________ _______________ are interchangeable. • View this in a equation: 1 L = 1 dm3 = ___________ cm3 = _________ mL

  33. Derived SI Units - Volume • When chemists measure the volumes of liquid and gases, they often use a non-SI unit called the liter, L. • **Another non-SI unit, the ________________, or ___, is used for smaller volumes. There are _____________ mL in 1 L. • Because there are also __________ cm3 in a liter, the 2 units, ____________ and __________ _______________ are interchangeable. • View this in a equation: 1 L = 1 dm3 = ___________ cm3 = _________ mL

  34. Derived SI Units - Volume • When chemists measure the volumes of liquid and gases, they often use a non-SI unit called the liter, L. • **Another non-SI unit, the milliliter, or mL is used for smaller volumes. There are 1000 mL in 1 L. • Because there are also __________ cm3 in a liter, the 2 units, ____________ and __________ _______________ are interchangeable. • View this in a equation: 1 L = 1 dm3 = ___________ cm3 = _________ mL

  35. Derived SI Units - Volume • When chemists measure the volumes of liquid and gases, they often use a non-SI unit called the liter, L. • **Another non-SI unit, the milliliter, or mL is used for smaller volumes. There are 1000 mL in 1 L. • Because there are also 1000cm3 in a liter, the 2 units, milliliterand cubic centimeter are interchangeable. • View this in a equation: 1 L = 1 dm3 = ___________ cm3 = _________ mL

  36. Derived SI Units - Volume • When chemists measure the volumes of liquid and gases, they often use a non-SI unit called the liter, L. • **Another non-SI unit, the milliliter, or mL is used for smaller volumes. There are 1000 mL in 1 L. • Because there are also 1000cm3 in a liter, the 2 units, milliliterand cubic centimeter are interchangeable. • View this in a equation: 1 L = 1 dm3 = 1000 cm3= 1000 mL

  37. Derived SI Units - Density • Ever heard the riddle: Which is heavier, a pound of feathers or a pound of lead? • Answer: Neither is heavier, a pound is a pound no matter what the object….but when you want to answer “lead” you are thinking about the object’s density. • For another example, an object made of cork feels lighter than a lead object of the same size. • What you are comparing in such cases is how massive objects are compared with their size.

  38. Derived SI Units - Density • This property is called __________________, which is the ratio of __________ to ______________, or ____________ divided by _______________________. • Mathematically, the relationship for density can be written: Density = mass/volume or D = MV • By the SI base units of measurement, density is expressed as kg/m3. Again, for a chemistry laboratory, we make the units smaller, ___/____ or _______/ ________.

  39. Derived SI Units - Density • This property is called Density, which is the ratio of mass to volume, or massdivided by volume. • Mathematically, the relationship for density can be written: Density = mass/volume or D = M/V • By the SI base units of measurement, density is expressed as kg/m3. Again, for a chemistry laboratory, we make the units smaller, ___/____ or _______/ ________.

  40. Derived SI Units - Density • This property is called Density, which is the ratio of mass to volume, or massdivided by volume. • Mathematically, the relationship for density can be written: Density = mass/volume or D = MV • By the SI base units of measurement, density is expressed as kg/m3. Again, for a chemistry laboratory, we make the units smaller, g/cm3 or g/mL.

  41. Derived SI Units - Density • Densities of some familiar materials (Table 4): • Solids Density at 20oC (g/cm3) Liquids Density at 200C (g/mL) • Cork .24 Milk1.031 • Ice .92 Water.998 • Sucrose (table sugar)1.59Sea Water 1.025 • Diamond 3.26Gasoline.67 • Lead11.35 Mercury13.6

  42. Derived SI Units - Density • Sample Problem A: • A sample of aluminum metal has a mass of 8.4g. The volume of the sample is 3.1 cm3. Calculate the density of aluminum. -Given: mass (m) = 8.4g & volume (v) = 3.1 cm3 - Unknown: Density (D) Density= mass/volume= 8.4 g/3.1 cm3 = 2.7 g/cm3

  43. Conversion Factors • A ratio derived from the equality between two different units that can be used to convert from one unit to the other is a _______________________ ___________________. • For example, suppose you want to know how many quarters there are in a certain number of dollars. • To figure out this answer, you need to know how _______________ and _________________ are related. • There are ____________ quarters in __________ dollar.

  44. Conversion Factors • A ratio derived from the equality between two different units that can be used to convert from one unit to the other is a conversion factor. • For example, suppose you want to know how many quarters there are in a certain number of dollars. • To figure out this answer, you need to know how _______________ and _________________ are related. • There are ____________ quarters in __________ dollar.

  45. Conversion Factors • A ratio derived from the equality between two different units that can be used to convert from one unit to the other is a conversion factor. • For example, suppose you want to know how many quarters there are in a certain number of dollars. • To figure out this answer, you need to know how quarters and dollars are related. • There are 4 quarters in 1dollar.

  46. Conversion Factors • There are 4 ways to express this: • 4 quarters/1 dollar = 1 • 1 dollar/4 quarters = 1 • 0.25 dollar/1 quarter = 1 • 1 quarter/0.25 dollar = 1 • Notice that each conversion factor equals _________. • That is because the top and bottom quantities divided in any conversion factor and ____________ to each other. In this case 4 quarters = 1 dollar.

  47. Conversion Factors • There are 4 ways to express this: • 4 quarters/1 dollar = 1 • 1 dollar/4 quarters = 1 • 0.25 dollar/1 quarter = 1 • 1 quarter/0.25 dollar = 1 • Notice that each conversion factor equals ONE. • That is because the top and bottom quantities divided in any conversion factor and ____________ to each other. In this case 4 quarters = 1 dollar.

  48. Conversion Factors • There are 4 ways to express this: • 4 quarters/1 dollar = 1 • 1 dollar/4 quarters = 1 • 0.25 dollar/1 quarter = 1 • 1 quarter/0.25 dollar = 1 • Notice that each conversion factor equals ONE. • That is because the top and bottom quantities divided in any conversion factor and equivalentto each other. In this case 4 quarters = 1 dollar.

  49. Conversion Factors • You can use conversion factors to solve problems through __________________ ____________________; which is a mathematical technique that allows you to use __________ to solve problems involving ________________. • For example, to determine the number of quarters in 12 dollars, you would use a unit conversion that allows you to change from dollars to quarters: • Number of quarters = 12 dollars x conversion factor

  50. Conversion Factors • You can use conversion factors to solve problems through dimensional analysis; which is a mathematical technique that allows you to use unitsto solve problems involving measurements. • For example, to determine the number of quarters in 12 dollars, you would use a unit conversion that allows you to change from dollars to quarters: • Number of quarters = 12 dollars x conversion factor

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