water 3-10

S h bonds break and reform again and individual

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Unformatted text preview: m again and individual molecules become energized. s Gaseous State of Water s When being heated, some molecules move rapidly and escape to atmosphere. s 1 gram water = gas: 540 calories Heat of Vaporization. Problem How many calories it takes for 1 g of water going from ice at 0C to steam at 100C? s Ice to water at 0C 79.7 calories s Water 0 to 100 C = 100 calories s 100C water to steam = 539.4 calories s Total = 719.1 calories s Gaseous state of Water Boiling Point: Temperature of water stops rising. s Energy introduced after this point is used to change state. s States of Water Does a slow boiling pot have the same T than a rapidly boiling pot? s What is the difference? s Rapidly boiling pot, water evaporates faster. s Gaseous State of Water s Distance between molecules is great in gaseous state. s Molecules move very fast s In food it is important that gases increase in volume. s In breads, volume is increased 1600-fold when water is converted to steam. Factors that affect boiling point of Water s At sea level, water boils at 100C s [1] Altitude: Atmospheric pressure varies with altitude. s For each increase of 960 feet above sea level, the boiling point of water is lowered by 1C. s More time to cook at higher altitudes. Factors that affect boiling point of Water Atmospheric Pressure decreases with a decrease in altitude. s Atmospheric Pressure at sea level = 14.7 lb/ft2. s Atmospheric Pressure at 5,000 ft = 12.3 lb/ft2. s Atmospheric Pressure at 10,000 ft 10.2 lb/ft2. s Boiling Water 1. Lives in Aspen, Colorado Which water will boil faster?? 2. Lives in Providence, RI Which food will be cooked sooner?? Factors that affect boiling point of Water. [2] Atmospheric Pressure: Boiling point may be increased above 100C by using a pressure cooker. s Steam is confined and more heat needs to be applied for water molecules to escape as steam. s Boling of Water Pressure Cooker good for high altitudes. s In commercial food processing, a partial vacuum can be achieved to simulate the effect of altitude on boiling points. This is done to avoid undesirable flavors s...
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