Temperature and Density

* = ‘important’ homework question

Temperature

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 Scales	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 OR Simply subtract 273.15 from ANY temp. quoted in K to obtain the equivalent °C value

Examples:

1. What is 50°C in Kelvin?

2. What is 200 K in Celsius?

Comparing the Fahrenheit , Kelvin and Celsius Temperature Scales

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
what, where?!..”

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 provided, describe
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 scales 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….

Temperature Ranges

	Discussion: If something is boiling, is it necessarily ‘hot’? 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’?

Density

Review: How was the property of density defined during a previous lecture?

Density:

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
by chemists?