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LECTURE 6.2 – TEMPERATURE SCALES
Today’s Learning Targets• LT 5.3 – I can define what STP is on an exit ticket• LT 5.4 – I can discuss how the kinetic energy of a gas molecules is related to the
temperature of the gas mixture on an exit ticket • LT 5.5 – I can define what absolute zero and relate it to the Kelvin temperature
scale on an exit ticket• LT 5.6 – I can convert between the Kelvin and Celsius temperature scales on an
exit ticket• LT 5.7 – I can explain Boyle’s Law, how it relates pressure and volume, and I can
calculate pressure and volume values for a given problem on an exit ticket
What are the temperature scales?
I. Temperature• The temperature that we
feel is created by the movement of atoms.
• The movement of gas molecules in the air creates our observable temperature
• The temperature is a measurement of the average energy of a sample
II. Temperature Scales• The 2 main
temperature scales in chemistry are the Celsius and Kelvin scales
• The Celsius scale sets the freezing point of water at 0 oC and the boiling point of water at 100 oC
What is STP?
I. STP• When working with gases,
reactions are normally carried out under standard temperature and pressure or STP
• STP is defined as 273 K and 1 atm
What is absolute zero?
I. Kelvin Scale• The other unit of
temperature used in chemistry is the Kelvin scale.
• The Kelvin scale sets 0 K as being absolute zero.
II. Absolute Zero• Absolute zero is the
temperature at which all molecular motion stops.
• Coldest possible temperature
• It is impossible to go below absolute zero (0 K) because molecular motion has stopped at this point.
How do we convert between Celsius and Kelvin
I. Converting Between Kelvin and Celsius • To convert from Celsius to Kelvin:
Kelvin = Co + 273• To convert from Kelvin to Celsius:
Celsius = Kelvin – 273
Class Example
• It is 33 oC outside, what is this temperature in Kelvin?
Table Talk
• If I have something at 298 K, what temperature is it in Celsius?
Stop and Jot
• You measure a reaction at 1250 oC, what is the temperature in Kelvin?