MEASUREMENT

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# MEASUREMENT - PowerPoint PPT Presentation

MEASUREMENT. CHOOSING THE CORRECT TOOL CALCULATED UNITS READING MEASUREMENTS TEMPERATURE CONVERSIONS ESTIMATING METRIC CONVERSIONS.

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### MEASUREMENT

CHOOSING THE CORRECT TOOL CALCULATED UNITS

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

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

• 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.
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).

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