# heatcurveWS - CHEMISTRY HEATING CURVE WORKSHEET 700 650 600...

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I f this curve is read from right to left, it is a Cooling Curve. The diagram below illustrates the steps involved to convert 10 g of solid ice at -20°C to 10 g of gaseous steam at 140°C. 10 g 10 g 10 g 10 g 10 g 10 g CHEMISTRY HEATING CURVE WORKSHEET -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Temperature •C 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 Time (seconds) Heating Curve for Water A B C D E F AB-Solid Phase BC-Liquid/Solid CD-Liquid Phase DE-Liquid/Vapor EF-Vapor Phase H 2 O (s) at -20°C H 2 O (l) at 0°C H 2 O (l) at 100°C H 2 O (s) at 0 °C H 2 O (g) at 100°C H 2 O (g) at 140°C A-B B-C C-D D-E E-F

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A. Solid Phase Solids are easily recognized by their ability to retain a fixed shape and definite volume. Particles making up a solid are held together in a rigid form. They are not free to move about or slide past one another and the solid does not have the ability to flow. (Although the particles of a solid do not move position to posi- tion, they do have motion in that they are constantly vibrating. To change the temperature of a solid, heat energy must be added. The amount of heat energy that changes the temperature of 1.0 g of a solid by 1.0°C is called its specific heat (c). Each substance has its own specific heat. The specific heat of ice is 2.1 Joules/g°C . In other words we must supply 1.0 gram of ice with 2.1 Joules of heat energy to raise its temperature by 1.0 °C. The general equation for calculating heat energy to change the temperature of a solid is: Heat = Mass x Specific Heat (solid) x Temperature Change Q = m c DT 10 g 10 g 10 g 10 g 10 g 10 g Calculate the heat necessary to change 10 g of ice (s) at -20 °C to 10 g of ice (s) at 0°C. (A-B) Q = mc Δ T = (10 g) (2.1 J/g°C) (20°C) = 420 J If you continue to add heat energy once the temperature of the ice reaches 0°C , the heat absorbed is called the heat of fusion (L f ) . This heat is used to cause a change of phase (from a solid to a liquid). This heat is increasing the potential energy of the molecules of the solid. No temperature change takes place.
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