Download Density - Canvas by Instructure

9/12/2013

Today:

Next Week
◦ Turn in Math Review & Intro to
Small Scale Chemistry
◦ Take Quiz 1
◦ Density:
 Concepts & Examples
◦ Introduce techniques for
experiment
◦ Before coming to lab:
 Read background and procedure
for “Chemical Changes”
experiment
 Handout is provided on Canvas
course website
 Taking measurements in chemistry
 Working with graduated cylinders
 Practice ACTIVE DATA ENTRY
◦ Perform Experiment
◦ Complete analysis and sample
problems for worksheet
Density

Density is a physical property of matter that describes the
relationship between mass and volume of a substance.

Density is an intensive property of matter - A substance will have
a characteristic density that is independent of the amount of the
substance present.

In lay terms, we might say it describes how "heavy" a substance is
(a misuse of the word).
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Density from an Atomic Perspective
Density from an Atomic Perspective
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5-step Method for Problem-solving
1.
Identify the UNKNOWN in the problem.
2.
Identify the GIVEN quantities and useful information.
3.
Choose the appropriate formulas & conversion
factors.
4.
Plan the solution.
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5.
Identify how you will use formulas & conversion factors.
Set up dimensional analysis tables. MAKE SURE UNITS ARE
CONSISTENT.
Isolate unknown variables in formulas.
Substitute the givens (in formulas) and SOLVE.
(Plug & Chug!)
Problem Solving Examples
Pure ethanol has a density of 0.789 g/cm3. What is the
volume of ethanol that must be measured (in fluid ounces)
to equal 14 g?
Given:: 1 fluid ounce ≈ 29.5 mL
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Problem Solving Examples
A neutron star has a density of about 100 million tons per
teaspoon (ton/tsp). What volume of a neutron star (in
cm3) would have the same mass as a Boeing 747, which
weighs 358,000 lbs.?
Given: 1 ton = 2000 lbs. & 1 tsp ≈ 4.92 cm3
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