Temperature and Density
|Reading: Ch. 2 sections 7 - 8||
2.7, questions 72, 74, 76, 78*, 82*
2.8, questions 86, 90, 92*, 94*, 96, 100*
* = ‘important’ homework question
Background: There are three temperature scales in common use today . Can
you name them?
How were the end points of the two ‘metric’ scales
defined? In other words,
what natural conditions define these respective temperature values ?
|The Centigrade and Kelvin
|The Centigrade scale compared to the
state of H2O
Converting between Degrees Celsius and Kelvin
Task: By looking at the above graph , describe how the °C and K scales are
related. What do they have in common ? What is different ?
| Simply add 273.15 to ANY temp. quoted in
°C to obtain
the equivalent K value
Simply subtract 273.15 from ANY temp. quoted in K to
obtain the equivalent °C value
1. What is 50°C in Kelvin?
2. What is 200 K in Celsius?
Comparing the Fahrenheit , Kelvin and Celsius Temperature
Discussion: We saw that the end points for the °C scale corresponded to
specific ‘natural’ temperatures – the same is true for the °F scale. What
‘natural’ temperatures do you think 0 °F and 100 °F correspond to in
nature. How about 212 °F and 32 °F?
“You want to put
Diagram: Fahrenheit, Celsius and Kelvin thermometers side by side.
|Question: What is the obvious error in the above diagram?|
Task: By looking at the previous diagram , or the slide
how the °C and °F scales are related. What do they have in common? What
is different ?
|The two basic differences between the
°C and °F
allow for equations relating them (conversion equations)
to be constructed:
For converting °C to °F:
For converting °F to °C:
Question: What is 90 °F in °C and in Kelvin?
Ask me about the extra credit temperature….
|Discussion: If something is boiling, is it
If it is frozen, is it necessarily ‘cold’?
Task: View and make brief notes on the ‘temperature scale’
slide. Think of
the ‘hottest’ and ‘coldest’ things you come into contact with on a daily basis
– where do they fit into the ‘bigger picture’?
|NOTE: THE FOLLOWING IS A REVIEW OF THE MATERIAL
WILL LEARN DURING LAB #2.
Review: How was the property of density defined during a previous lecture?
Where: ‘amount of matter’ = _______________
Discussion: What is the S.I. unit of density? Is this a convenient unit?
=> Density =
Question: What are the two ‘convenient’ derived S.I. units of density used