Chapter 17: Change of Phase Flashcards

1
Q

Steam burns are more damaging than burns caused by boiling water because steam

A

gives up change of phase energy when it condenses and has more energy per kilogram than boiling water

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2
Q

When a gas is changed to a liquid state, the gas

A

releases energy

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3
Q

As atmospheric pressure is increased, the boiling temperature of a liquid

A

goes up

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4
Q

If we slowly pump out all the air over a bowl of water until it is in a vacuum,

A

it will boil, then freeze

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5
Q

Food in a pressure cooker is cooked faster because of the

A

higher temperatures reached in a sealed container.

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6
Q

Adding pressure to ice causes ice to

A

melt

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7
Q

Near the top of a mountain, water in an open pot boils at

A

a lower temperature than at sea level

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8
Q

The food in a refrigerator is cooled by

A

vaporization of the refrigerating fluid

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9
Q

Compared to a glass of ice water with ice in it, on a warm day a glass of pure ice-cold water without ice will warm up

A

faster

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10
Q

If you heat an ice bucket of water for several hours until only a small amount of ice remains, the temperature of water will be

A

0° C

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11
Q

When warm air rises, it

A

expands and cools

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12
Q

If you add heat for 35 minutes to a pan with 2 kgs of 100°C water in it the temperature of the remaining water will be

A

100°C

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13
Q

How many joules does it takes to vaporize 1 gram of water?

A

2255 J (sometimes rounded up to 2260 J)

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14
Q

When water in the vapor phase condenses to liquid in the air, the surrounding air

A

warms

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15
Q

When the air pressure is lowered,

A

it takes less heat to boil water

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16
Q

The change of phase from liquid to gaseous?

A

Evaporation

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17
Q

The change of phase from solid to gaseous, bypassing the liquid phase?

A

Sublimation

18
Q

The change of phase from gaseous to liquid?

A

Condensation

19
Q

Rapid evaporation that takes place within a liquid as well as at its surface?

A

Boiling

20
Q

The process of melting under pressure and the subsequent refreezing when the pressure is removed?

A

Regelation

21
Q

A device that transfers heat out of a cool environment and into a warm environment?

A

Heat pump

22
Q

The amount of energy required to change a unit mass of a substance from solid to liquid (and released in the reversed process).

A

Latent heat of fusion

23
Q

The amount of energy required to change a unit mass of a substance from liquid to gas (and released in the reverse process).

A

Latent heat of vaporization

24
Q

A solid must _______ energy to _______.

A

A solid must absorb energy to melt.

25
Q

A liquid must _______ energy to _______.

A

A liquid must absorb energy to vaporize.

26
Q

A gas must _______ energy to ________.

A

A gas must release energy to liquify.

27
Q

A liquid must _______ energy to ________.

A

A liquid must release energy to solidify.

28
Q

When H2O in the vapor phase condenses, is the surrounding air warmed or cooled?

A

Warmed. The change of phase is from vapor to liquid, which releases energy, so the surrounding air is warmed.

29
Q

One calorie is equal to how many joules?

A

4.187 joules

30
Q

Heat of ___________ is either the energy required to separate molecules from the liquid phase or the energy released when gas condenses to the liquid phase.

A

vaporization

31
Q

Heat of _______ is either the energy needed to separate molecules from the solid phase or the energy released when bonds form in a liquid that change it to the solid phase.

A

fusion

32
Q

______ has more potential energy because the molecules are relatively free of each other and are not bound together as in the liquid phase.

A

Steam

33
Q

How much energy is transferred when 1 g of steam at 100 degrees C condenses to water at 100 degrees C?

A

540 calories of energy. One gram of steam at 100 degrees C transfers 540 calories of energy when it condenses to become water at same temperature.

34
Q

How much energy is transferred when 1 g of boiling water at 100 degrees C cools to ice water at 0 degrees C?

A

100 calories. One gram of boiling water transfers 100 calories when it cools 100 degrees C to become ice water.

35
Q

How much energy is transferred when 1 g of ice water at 0 degrees C freezes to ice at 0 degrees C?

A

80 calories. One gram of ice water at 0 degrees C transfers 80 calories to become ice at 0 degrees C.

36
Q

How much energy is transferred when 1 g of steam at 100 degrees C turns to ice at 0 degrees C?

A

720 calories. One gram of steam at 100 degrees C transfers to the surroundings 720 calories to become ice at 0 degrees C.

37
Q

If 4 g of boiling water is poured onto a cold surface and 1 g rapidly evaporates, if evaporation takes 540 calories from the remaining 3 g of water and no other heat transfer takes place, what will be the temperature of the remaining 3 g?

A

0 degrees C. The remaining 3 g will turn into 0 degree C ice.

38
Q

When snow forms in clouds, the surrounding air is ________.

A

warmed (the change of phase is from gas to solid which releases energy).

39
Q

Which involves the greatest number of calories: a) Condensing 1 g of 100 degree C steam to 100 degree C water; b) Cooling 1 g of 100 degree C water to 1 gram of 0 degree C ice; c) Cooling 1 g of 0 degree C ice to near absolute zero; d) All about the same

A

a) Condensing 1 g of 100 degree C steam to 100 degree C water, which takes 540 calories.

40
Q

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

A

a) melts; For each gram of ice that melts, 80 calories is taken from the beverage.

41
Q

Boiling point is lower with

A

lower atmospheric pressure

42
Q

The process of boiling: a) cools the water being boiled; b) depends on atmospheric pressure; c) is a change of phase below the water surface; d) All of the above

A

d) All of the above