The critical pressureis the ______________ pressure the substance can exist as a liquid at the critical temperature heating curve 11.When energy is removed condensation begins at ____ 12.Between points D to C heat is ___________________ and temperature is ___________________.

6 13.During a phase change the change in energy is a loss of _____________________ energy since temperature measures kinetic energy and kinetic energy is constant.. 14.Draw a heating curve representing energy of ice at -20oC changing to water at 30oC 15.Draw a heating curve representing energy of steam at 140oC changing to water at 30oC single step Heat calculations H2O Hf= 6.009 kJ/mole Cs= 2.10 J/goC mp = know Hv= 40.79 kJ/mole Cl= 4.184 J/goC Bp = know Cg= 2.00 J/goC 17.1 Same phase--temperature changes q = mCT C= specific heat capacity (J/g oC) -- the energy needed to raise the temperature of 1 gram 1oC the ability of a substance to store energy as heat. 1.Calculate the heat required to cool 50.0 g water from 80.0oC to 10.0oC . 2.How much energy is needed to warm 200. g of ice from -30.oC to -10.0oC if the C of ice is 2.10 J/g oC? 3.Calculate the heat required to melt 50.0 g ice at 0.0oC to water 0.0oC. Hvmolar heat of vaporization= energy required to vaporize 1 mole 40.79 kJ/mol + H2O(l) H2O(g) molarheat of condensationis the heat that must be released condense a vapor -- opposite in sign to Hv

7 4.Calculate the heat required to condense 50.0 g steam at 100.oC to water at 100.oC. multiple step Heat calculations HEATING CURVE Calculations(phase and temperature changes) 5. Calculate the energy in kJ needed to convert 180.2 g ice at –40.0oC to steam at130.0oC. Hf= 6.009 kJ/mole Hv= 40.79 kJ/mole Cs= 2.10 J/goC Cl= 4.184 Cg= 2.00 J/goC AC increase temperature of solid mCsTs _______ kJ 1000 CD melt solid nHf_______ kJ DE increase temperature of liquid mClTl_______ kJ 1000 EF vaporize liquid nHv _______ kJ FG increase temperature of gas mCgTg_______ kJ 1000 TOTAL = 6.Suppose 100. kJ were added to the system above. What would be the final state and temperature?

7.What is the change in energy when 92.0 g ethanol cools from 70.0oC to -140.oC?

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- Summer '16
- Thermodynamics, Intermolecular force