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17 Cards in this Set
- Front
- Back
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Evaporation
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The cahnge of phase at the surface of a liquid as passes to the gaseous phase. This is caused by the random motion of molecules that occasionally escape from teh liquid surface. Cooling of the liquid results.
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Condensation
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The change of phase from gas to liquid; the opposite of evaporation. Warming of the liquid results.
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Boiling
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A rapid evaporation that takes place within the liquid as well as at its surface. As with evaporation, cooling of the liquids.
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Regelation
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The process of melting under pressure and the subsequent refreezing when the pressure is removed
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Why does warm moist air form clouds when it rises?
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as it rises it expands and chills as it chills water vapor molecules stick together after colliding rather than bouncing off of each other. If there are larger slower moving particles or ions present and sufficient buildup there will be a cloud
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What is the basic difference bewteen a cloud and fog?
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altitude
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Distinguish between evaporation and boiling
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under the right conditions, evaporation can take place beneath the surface of a liquid., forming bubbles of vapor that are buoyed to the surface where they escape. This change of phase throughout a liquid rather than only at the surface is boiling.
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Why does water not boil at 100 degrees celsius when it is under a pressure of more than one atmosphere?
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At temperatures below the boiling point, the vapor pressure in bubbles is not great enough, so bubbles do not form until the boiling point is reached. At this temp, 100 c for water at atmospheric pressure, molecues are energetic enough to exert a vapor pressure as great a the surrounding water, if pressure is increased the moleucles have to move faster to exert the pressure to boil
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Why is the boiling point of water lower at high altitude?
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Lowered pressure at high altitueds decreases the boiling point because the pressure on the water is decreased so it is easier for the vapor pressure to form its bubbles
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What causes food to cook faster in a pressure cooker than ina an open pot?
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Because it does not allow the vapor to excape increasing the presure on the surface which prevents boiling and therefore increases the temperature of the water so the food cooks faster
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What is it that cools when boiling occurs- the water that leaves in the form of vapor or the water left behind?
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the water left behind
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We observe that the temperature of boiling water doesn't increase with continued energy input. Explain how this observation is evidence that boiling is a cooling process
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If cooling did not take place, continued input of energy to a pot of boiling water would result in a continued increase in temperature. The reason a pressure cooker reaches higher temperatures is because it prevents normal boiling, which in effect prevents cooling.
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When will water boil at a temperature less than 100 Degrees Celsius?
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If the pressure in the jar is slowly reduced by a vacuum pump, the water will start to boil, continued boiling at lower and lower pressure results in the freezing of water.
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We can add energy to wate and boil it to form steam. Isn't is a contradiction to say we can boil water to form ice? Explain.
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Continued coolign by boiling causes ice to form over the surface of the bubblign wate. Boiling and freezing are taking place at the same time!
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What happens to the hexagonal open structure of ice when sufficient pressure is applied to it?
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Because H2O molecules form open structurs in solid phase, the application of pressure lowers the melting point of ice. The crystals are crushed to the liquid phase.
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What happens to the water that results from crushing crystals when the pressure is removed?
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The molecules crystallize and refreezing occurs.
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Why does a wire not simply cut a block of ice in half when it passes through the ice?
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As the wire cuts the crystal structures refreeze behind it so once the wire is through the ice is still uncut
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