A refrigerator is the reverse of an engine: Work is performed to remove heat from a system, making it colder. The efficiency of a refrigerator (often termed the “coefficient of performance”) is defined as
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Physical Chemistry
- What are the two ways that a final chemical state of a system can be more probable than its initial state?arrow_forwardA pot of cold water is heated on a stove, and when the water boils, a fresh egg is placed in the water to cook. Describe the events that are occurring in terms of the zeroth law of thermodynamics.arrow_forwardThe formation of aluminum oxide from its elements is highly exothermic. If 2.70 g Al metal is burned in pure O2 to give A12O3, calculate how much thermal energy is evolved in the process (at constant pressure).arrow_forward
- 2. In which of the following reactions is there a significant transfer of energy as work from the system to the surroundings? This occurs if there is a change in the number of moles of gases. C(s) + O2(g) → CO2(g) CH4(g) + 2 O2(g) → CO2g) + 2 H2O(g) 2 C(s) + O2(g) → 2 CO(g) 2 Mg(s) + O2(g) → 2 MgO(s)arrow_forwardWhen 1.000 g of ethylene glycol, C2H6O2, is burned at 25C and 1.00 atmosphere pressure, H2O(l) and CO2(g) are formed with the evolution of 19.18 kJ of heat. a Calculate the molar enthalpy of formation of ethylene glycol. (It will be necessary to use data from Appendix C.) b Gf of ethylene glycol is 322.5 kJ/mol. What is G for the combustion of 1 mol ethylene glycol? c What is S for the combustion of 1 mol ethylene glycol?arrow_forwardThe statement Energycan beneithercreatednor destroyedis sometimes used as an equivalent statement of the first law of thermodynamics. There areinaccuracies to the statement, however. Restate it tomake it less inaccurate.arrow_forward
- When 1.000 g of gaseous butane, C4H10, is burned at 25C and 1.00 atm pressure, H2O(l) and CO2(g) are formed with the evolution of 49.50 kJ of heat. a Calculate the molar enthalpy of formation of butane. (Use enthalpy of formation data for H2O and CO2.) b Gf of butane is 17.2 kJ/mol. What is G for the combustion of 1 mol butane? c From a and b, calculate S for the combustion of 1 mol butane.arrow_forwardThe octane number of gasoline is based on a comparison of the gasolines behavior with that of 2,2,4-trimethylpentane, C8H18(), which is arbitrarily assigned an octane number of 100. The standard enthalpy of combustion of this compound is 5456.6 kJ/mol. (a) Write the thermochemical equation for the combustion of 2,2,4-trimethylpentane. (b) Use the standard enthalpies of formation in Appendix G to calculate the standard enthalpy of formation of 2,2,4-trimethylpentane.arrow_forwardThe enthalpy of vaporization for water is 40.65 kJ mol-1. As a design engineer for a project in a desert climate, you are exploring the option of using evaporative cooling. (a) If the air has an average volumetric heat capacity of 0.00130 J cm-3 K-1, what is the minimum mass of water that would need to evaporate in order to cool a 5 m? 5 m room with a 3 m ceiling by 5°F using this method? (b) Is this a spontaneous or nonspontaneous process?arrow_forward
- Which of the following processes will lead to a decrease in the internal energy of a system? (1) Energy is transferred as heat to the system; (2) energy is transferred as heat from the system; (3) energy is transferred as work done on the system; or (4) energy is transferred as work done by the system. (a) 1 and 3 (b) 2 and 4 (c) 1 and 4 (d) 2and3arrow_forwardA piece of lead of mass 121.6 g was heated by an electrical coil. From the resistance of the coil, the current, and the Time the current flowed, it was calculated that 235 J of heat was added to the lead. The temperature of the lead rose from 20.4C to 35.5C. What is the specific heat of the lead?arrow_forwardExplain inyour own words why work done by the system is defined as the negative of pV, not positive pV.arrow_forward
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