Test 2- Phase change and Matter Flashcards
Solid
Doesn’t take shape of the container, definite volume, vibrational energy, lowest kinetic energy, no change in volume due to pressure.
Liquid
Takes shape of container, definite volume, vibrational and rotational energy, no change in volume due to pressure.
Gas
Takes shape of container, no definite volume, vibrational and rotational and translational energy, highest kinetic energy, pressure can be applied and volume will change.
Plasma
Just like gas except its composed of ions and electrons.
Both Liquids and gases are considered
Fluids
Phases at atomic level
Endothermic
Energy going in/being absorbed
Exothermic
Energy coming out/being released
Endothermic examples
Sweating (energy going into sweat from your body in order to evaporate), Panting dogs (same as sweating since panting is the equivalent of sweating for dogs), chills when its 100 degrees and you get out of the pool (energy is being absorbed by the water from your body to evaporate)
Exothermic Examples
Making ice cubes (energy is being released in order to solidify)
Phase changes
•S > L - Melting - endothermic •L > S - Freezing - Exothermic •L > G - Evaporating or boiling - Endothermic •G > L - Condensing - Exothermic •S > G - Sublimation - Endothermic
Phase change diagram
Heat of Fusion
The energy needed in joules to change one gram of substance from S>L or L>S
Chemical energy is called
Entropy
Energy is measured in
Joules
Cp
specific heat: Amount of energy needed in joules to raise on gram of substance by one Kelvin J/g degree Celsius or J/g degree Kelvin
Graph down vs. Graph up
•Down graph: energy released •Up Graph: Energy put in
KE vs. PE
•KE increases as temperature increases (lines going up/down) •PE energy increases during phase change (straight line)
Why is steam burn worse than hot water burn?
Hot water only transfers the energy it needs to evaporate while steam first needs to condense, then evaporate.
S>L vs. L>G
•S>L 334 J/g needs to overcome interatomic molecules •L>G 2260 J/g needs to overcome intermolecular and air pressure •More energy needed to go from L>G because of bonds and the air pressure acts as “bouncers” pushing the escaped liquid molecules back
Second law of thermodynamics
Describes direction of heat flow. Heat flows from a hotter object to a cooler one. Entropy of a system and its surroundings increase. Entropy is the fact that everything is moving towards disorganization.
Temperature _____ as water freezes
remains the same
Freezing point is the same as
melting point
Boiling point is the same as
condensing point
Water can exist as a ____ at zero degrees Celsius
liquid or a solid
Kinetic energy ______ during phase change
Remains the same
It will take ______ to cook an egg at lower pressure
more time
Temperature of boiling water in Death valley is _____
higher
KE=
KE= Average temperature. Doesn’t increase during phase change because temperature remains the same.
Pipes burst in the winter because __________
water expands as it freezes
Spaghetti takes longer to cook in the mountains because
the boiling temperature in higher altitudes is lower than at sea level so the pasta takes longer to cook. This is because there is less air pressure acting as bouncers, pushing the water back (air pressure).
Water freezes and ice melts at 0°C since
freezing point and melting point are the same
Water boils at
100dC
Ice is warmed to the melting point-
The frozen/solid molecules vibrate increasingly until they break apart. 0°C
Water is warmed to the boiling point-
Liquid molecules move faster and faster until they break apart. 100°C
Water is cooled to the freezing point-
Liquid molecules move slower and slower until they begin to stick together. 0°C
Lower air pressure, increased altitude will
not affect freezing point and melting point and decrease boiling point.
In a pressure cooker, the increased air pressure will
create a higher boiling point, making the food cook faster.
Drinking bird
The water is absorbed by the bird’s head, making it heavier which causes it to tip over because of gravity. The water evaporates off the head, cooling the temperature and causing the fluid to condense and the pressure to decrease. The water is forced to the tip of the bird. The vapor goes pack up and the bird becomes upright. Vapor travels from them bottom to the top until the pressure in both spheres equalize and the bird begins the process over again.
Miracle thaw does not possess amazing properties.
It is simply a slab of black aluminum with grooves. Aluminum is a good conductor, but not a superconductor. Also, their marketing principle that heat is transferred to the frozen food is simply a restatement of the second law of thermodynamics.