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Units of Measure: Quantity, Measurement, and Standards

Understand the concepts of quantity, measurement, and standards in the SI system, and learn about the units of mass, length, temperature, and time. Explore the difference between mass and weight, and how to convert units within the SI system.

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Units of Measure: Quantity, Measurement, and Standards

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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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