What is the heat of fusion of water in joules/g?
334 joules/g
What is heat of fusion?
The amount of energy needed to change any substance from solid to liquid and from liquid to solid
What is heat of vaporization?
The amount of energy needed to change any substance from liquid to gas and from gas to liquid
What is the heat of vaporization in joules/g?
2256 joules/g
When snow forms in the clouds, the surrounding air is:
a) cooled
b) warmed
c)insulated
d)thermally conducting
warmed
The change of phase from gas to solid releases energy
Ice is put in a picnic cooler. To speed up the cooling of cans of beverage, it is important that the ice
a) melts
b) is prevented from melting
c) be in large chunks
d)none of the above
melts
For each gram of ice that melts, 540 calories is taken from the beverage
What are the four common phases that involve transfer of internal energy?
solid
liquid
gas
plasma (vapor disintegrates to ions and electrons)
Does energy cause molecules to move more rapidly or more slowly?
more rapidly
What is evaporation?
Change of phase from liquid to gas
Which of the following is false about evaporation?
a)molecules in a liquid move randomly at various speeds, continually colliding into one another
b)some molecules gain kinetic energy while others lose kinetic energy during collision
c)some energetic mole
All are true
-molecules in a liquid move randomly at various speeds, continually colliding into one another
-some molecules gain kinetic energy while others lose kinetic energy during collision
-some energetic molecules escape from the liquid and become g
What is sublimation?
form of phase change from solid to gas
ex: dry ice (solid CO2 molecules), moth balls, frozen water
What is true about condensation?
a)opposite of evaporation
gas--> liquid
b)warming process from a gas to a liquid
c) gas molecules near a liquid surface are attracted to the liquid
d)they strike the surface with increased kinetic energy, becoming part of
All are true statements
-condensation is the opposite of evaporation
-form of phase change from a gas to a liquid
-warming process from a gas to a liquid
-gas molecules near a liquid surface are attracted to the liquid
-they strike the surface with increa
What is happening to the kinetic energy during the condensation process?
Kinetic energy is absorbed by the liquid resulting in increased temperature
Why do you feel warmer in a moist shower stall?
You feel warmer in a moist shower stall because the rate of condensation exceeds the rate of evaporation
Which will produce a more damaging burn: steam or boiling water?
Steam will produce a more damaging burn because it releases a lot of energy when it condenses into a liquid and moistens the skin
A cold soda pop can is wet in warm air because slow-moving molecules make contact with the cold surface and condense.
This is an example of
condensation
True or False: In dry cities, the rate of evaporation from your skin is greater than the rate of condensation, so you feel colder
True
In dry cities, the rate of evaporation from your skin is greater than the rate of condensation, so you feel colder (releasing heat)
True or False: In humid cities, the rate of evaporation from your skin is less than the rate of condensation, so you feel warmer
True
In humid cities, the rate of evaporation from your skin is less than the rate of condensation, so you feel warmer (condensation makes you warmer, think shower)
True or False:
In condensation in the atmosphere: when the temperature of the atmosphere is low, the water molecules in the air move slowly
True
In condensation in the atmosphere, when the temperature of the atmosphere is low, the water molecules in the air move slowly
True or False:
In condensation in the atmosphere: slow- moving water molecules stick together, causing condensation
True
In condensation in the atmosphere, slow-moving water molecules do stick together which is what causes condensation
If bits of coals do not stick to your feet when firewalking, its best if your feet are:
a)wet
b)dry
c)wet and dry
d)none
Wet
The energy that vaporizes water is energy that doesn't burn your feet.
When you step out after a hot shower you feel cold, but you can feel warm again if you step back into the shower area. Which process is responsible for this?
Condensation
When you step back into the shower area, the steam that is present condenses on your body, causing it to warm up
What is melting?
Melting occurs when a substance changes phase from a solid to a liquid
-opposite of freezing
-when heat is supplied to a solid, added vibration breaks molecules loose from the structure and melting occurs
What is freezing?
Freezing occurs when a substance changes phase from liquid to solid
-opposite of melting
-when energy is continually removed from a liquid, molecular motion decreases until the forces of attraction bind them together and formation of ice occurs
From solid to liquid to gas phase, do you add or remove energy?
Add energy
From gas to liquid to solid phase, do you add or remove energy?
Remove energy
From solid to liquid to gas, is energy absorbed or released?
Energy is absorbed from solid to liquid to gas
From gas to liquid to solid, is energy absorbed or released?
Energy is released from gas to liquid to solid