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13 Cards in this Set
- Front
- Back
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What is a BTU ?
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British Thermal Unit, The amount of heat required to raise the temperature of 1 lb. of water 1 degree fahrenheit
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What is Sensible Heat ?
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It is the heat that is absorbed or rejected that causes a change in temperature but not a change in state.
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What is Latent Heat ?
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Heat energy absorbed or rejected when a substance is changing state and there is no change in temperature.
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What is Latent Heat of Fusion ?
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The heat that changes the physical state of a substance from a liquid to a solid or from a solid to a liquid without temperature change.
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What is Latent Heat of Vaporization ?
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The latent heat absorbed when refrigerant evaporates.
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How many btu's does it take to melt 1 lb. of ice ?
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144 btu's at 32 degrees Fahrenheit.
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How many btu's will it take to boil 1 lb. of water to steam ?
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It takes 970 btu's of energy to convert 1 lb. of water into steam.
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How many btu's to condense 1 lb. of steam to water ?
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180 btu's
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Water expands how many times its weight in volume when it flashes to steam ?
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At 212º F water expands approximately 1700 times its original volume. 20 cubic feet of water expands to approximately 48,000 cubic feet of steam, this will fill a room that is 10 feet high, 48 feet wide and 100 feet long.
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What is Specific Heat ?
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The amount of heat required to raise the temperature of 1 lb. of a substance one degree Fahrenheit.
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What is a Ton of cooling based on ?
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It is based on the amount of heat needed to melt one ton (2000 lbs.) of ice in a 24 hour period. One Ton of cooling is equal to 12000 Btu/Hr.
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How many btu's must you remove to freeze one pound of water to ice ?
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144Btu's
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What is Enthalpy ?
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(1) The amount of heat a substance contains from a predetermined base or point.
(2) A thermodynamic property of a substance also called total heat, which is a measure of the heat content of a material. When a change occures at constant pressure, as when water is boiled, the change in enthalpy is equal to the heat added, in this case the latent heat. |
