UNIT 1A: MEASUREMENT IN CHEMISTRY

MEASUREMENT AT THE CONCLUSION OF OUR TIME TOGETHER, YOU SHOULD BE ABLE TO: 1. Explain the difference between the two types of observations 2. Know and explain the difference between accuracy and precision. 3. Begin to learn the metric prefixes. 4.Distinguish between accuracy and precision.

TYPES OF OBSERVATIONS AND MEASUREMENTS – PAGE 25 We make QUALITATIVE observations of reactions — changes in color and physical state. We also make QUANTITATIVE observations that involve MEASUREMENTS with numbers and units.

SI MEASUREMENT Le Système International d‘Unités Adopted in 1960 by the General Conference on Weights and Measures. International Standards are kept in France. Among countries with non- metric usage, the U.S. is the only country significantly holding out. The U.S. officially adopted SI in Liberia and Myanmar are changing over. Information from U.S. Metric Association Liberia

BASE SI UNITS QuantityUnitSymbol Lengthmeterm Masskilogramkg TemperaturekelvinK Timeseconds Amount of Substance molemol Luminous Intensity candelacd Electric Current amperea

STATING A QUANTITATIVE MEASUREMENT In every measurement there is a  Number (Quantity) followed by a  Unit from a measuring device

METRIC PREFIXES – PAGE 40

You Will Need to Know: The Grand Master King Henry Died by Drinking Chocolate Milk Monday Night Prior

METRIC PREFIXES YOU NEED TO KNOW – PAGE 40

1 meter (m) 1 kilometer (km) 1 dm (decimeter) 1 cm (centimeter) 1 mm (millimeter) 1  m (micrometer) 1 nm (nanometer) 10 3 meters = 1 km 10 dm = 1 m 100 cm = 1 m 10 3 mm = 1 m 10 6  m = 1 m 10 9 nm = 1 m

ACCURACY & PRECISION – PAGE 25

MEASUREMENT? – PAGE 26

Measure These!

Lab Equip Precision Prediction 1 – 5 1 = best Your Reading Volume Reading #2 Average Reading Actual Accuracy Ranking Burette 50 mL Cylinder 250 mL Beaker 250 mL Cylinder 250 mL Flask

Volume!

Length and Volume 1 m = 10 dm therefore 1 m 3 = 10 3 dm 3 1 dm = 10 cm therefore 1 dm 3 = 10 3 cm 3 1 L = 1 dm 3 and 1 L = 10 3 mL so 1 L = 1 dm 3 = 10 3 mL = 10 3 cm 3 = 10 3 cc so This means that 1 milliliter (mL) is the same as 1 cubic centimeter (cc). These terms are often used interchangeably.

OTHER DERIVED SI UNITS QuantityUnitSymbol Volume cubic meter m3m3m3m3 Density kilograms per cubic meter kg/m 3 Speed meter per second m/s Newton kg m/ s 2 N Energy Joule (kg m 2 /s 2 ) J Pressure Pascal (kg/ms 2 ) Pa

MEASUREMENT LET’S SEE IF YOU CAN: 1. Explain the difference between the two types of observations 2. Give examples of 5 basic SI measuring units 3. Give examples of 3 different derived units from the basic SI units 4. Vary the amounts of the SI measuring units with 10 different prefixes and define each 5. Explain the difference between mass and weight 6. List and explain 5 different units for volume.

LEARNING CHECK Match L) length M) mass V) volume ____ A. A bag of tomatoes is 4.6 kg. ____ B. A person is 2.0 m tall. ____ C. A medication contains 0.50 g Aspirin. ____ D. A bottle contains 1.5 L of water. M L M V

LEARNING CHECK What are some U.S. units that are used to measure each of the following? A. length B. volume C. weight D. temperature

WHICH METRIC PREFIX IS GENERALLY USED?

LEARNING CHECK m = 1 ___a) mm b) km c) dm g = 1 ___ a) mg b) kg c) dg L = 1 ___a) mL b) cL c) dL m = 1 ___ a) mm b) cm c) dm

LEARNING CHECK Select the unit you would use to measure 1. Your height a) millimeters b) meters c) kilometers 2. Your mass a) milligramsb) grams c) kilograms 3. The distance between two cities a) millimetersb) meters c) kilometers 4. The width of an artery a) millimetersb) meters c) kilometers