Physics/Chemistry Flashcards
(85 cards)
What is a liquid?
- Heat added to change from solid into a liquid
- Kinetic energy not enough to overcome van der Waals forces - atoms move about but stay in non-fixed structure
What is a gas?
- more heat is added to change from a liquid to a gas
- Kindetic energy builds enough to break van der waal forces and atoms are free to move about
What is kinetic energy produced from?
All the atoms moving and colliding.
What is the definition of energy?
The ability to do work
What is the heat of fusion?
Potential energy increases and molecules can do work
Which state has the most potential energy? Why?
Gas - the molecules want to be close to each other but have so much energy, they can’t.
What is the scientific definition of equilibrium?
When energy transfer between 2 objects is equal
What is the definition of temperature?
Numerical ranking of hot or cold; the degree of hotness or coldness of a body.
What is the unit of measurement of temperature?
Kelvin/Celsius
What are properties of temperature?
Increases when heated
Decreases when cooled
What is the definition of heat?
Energy that is transferred as a result of a temperature difference/a form of energy which flows from a hotter region to a cooler region
What is the unit of measurement for heat?
Joule
What are properties of heat?
Flows from a hot area to a cold area.
What does critical temp mean?
Temp at which a substance can’t be liquefied no matter how much pressure is applied
Ex. Oxygen in cylinder will never be a liquid at room temp
What is the definition of boiling point?
Temp at which the vapor pressure of a liquid equals atmospheric pressure
What is the definition of absolute zero?
Temp at which no further heat energy can be extracted from any object
Ex. 237.25 C - temp at which all molecular motion stops
What is specific heat?
Amount of heat (energy) required to raise the temperature of 1 kg of a substance by 1 degree centigrade or kelvin
How many joules are in 1 calorie?
4.18 J
What is the heat of fusion?
Amount of heat necessary to convert (overcome van der Waal forces and allow molecules to move more freely) a solid into a liquid at its normal melting point
What is the heat of vaporization?
Amount of heat necessary to convert (overcome van der Waal forces and allow molecules to escape into a gas phase) a liquid into a gas at its normal boiling po
Why is it important to know the critical temperature of gases?
The pressure gauge can mean different things based on if the gas is the liquid phase or gas phase in the tank.
- O2 - gauge is linear
- N2O, can’t tell how much is left because pressure is always the same - need to weigh to determine how much is actually left
At what temp is N2O a gas?
97.7 F and above
At what temp is CO2 a gas?
88 F and above
At what temp is O2 a gas?
-119 F and above