350 likes | 555 Views
MEASUREMENT. CHOOSING THE CORRECT TOOL CALCULATED UNITS READING MEASUREMENTS TEMPERATURE CONVERSIONS ESTIMATING METRIC CONVERSIONS.
E N D
MEASUREMENT CHOOSING THE CORRECT TOOL CALCULATED UNITS READING MEASUREMENTS TEMPERATURE CONVERSIONS ESTIMATING METRIC CONVERSIONS
SI measurement • Le Système international d'unités • The only countries that have not officially adopted SI are Liberia (in western Africa) and Myanmar (a.k.a. Burma, in SE Asia), but now these are reportedly using metric regularly • Metrication is a process that does not happen all at once, but is rather a process that happens over time. • Among countries with non-metric usage, the U.S. is the only country significantly holding out. The U.S. officially adopted SI in 1866. Information from U.S. Metric Association
Length: Centimeters and Millimeters centimeters millimeters
Measurement and Significant Figures • Every experimental measurement has a degree of uncertainty. • The volume, V, at right is certain in the 10’s place, 10mL<V<20mL • The 1’s digit is also certain, 17mL<V<18mL • A best guess is needed for the tenths place.
Volume Displacement A solid displaces a matching volume of water when the solid is placed in water. 33 mL 25 mL
The Top Loading Balance • These balances are used when an accuracy of +/- 0.1 g is sufficient. • Before weighing check that the balance is displaying grams. • Zero or Tare the balance by pressing on the Zero button.
TEMPERATURE - Fahrenheit, Celsius, and Kelvin temperature scales
Calculations Using Temperature • Generally require temp’s in kelvins • T (K) = t (˚C) + 273 • Body temp = 37 ˚C + 273 = 310 K • Liquid nitrogen = -196 ˚C + 273 = 77 K
Why is this stuff important?
Platinum Mercury Aluminum DENSITY - an important and useful physical property 13.6 g/cm3 21.5 g/cm3 2.7 g/cm3
Problem A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3).
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams?
Learning Check Osmium is a very dense metal. What is its density in g/cm3 if 50.00 g of the metal occupies a volume of 2.22cm3? 1) 2.25 g/cm3 2) 22.5 g/cm3 3) 111 g/cm3
Learning Check What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? 1) 0.2 g/ cm3 2) 6 g/m3 3) 252 g/cm3 33 mL 25 mL
Learning Check Which diagram represents the liquid layers in the cylinder? (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) 2) 3) K W V V K W W V K
Learning Check If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g of blood are given? 1) 0.548 L 2) 1.25 L 3) 1.83 L
Learning Check A group of students collected 125 empty aluminum cans to take to the recycling center. If 21 cans make 1.0 pound of aluminum, how many liters of aluminum (D=2.70 g/cm3) are obtained from the cans? 1) 1.0 L 2) 2.0 L 3) 4.0 L