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If the heat capacity varies with temperature, a better form of equation 2.9 is to solve
A 50.0-g sample of white phosphorus is heated from 298 K to 350K. If its molar heat capacity is
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Physical Chemistry
- Nitrogen gas (2.75 L) is confined in a cylinder under constant atmospheric pressure (1.01 105 pascals). The volume of gas decreases to 2.10 L when 485 J of energy is transferred as heat to the surroundings. What is the change in internal energy of the gas?arrow_forwardIn a coffee-cup calorimeter, 50.0 mL of 0.100 M AgNO3 and 50.0 mL of 0.100 M HCl are mixed to yield the following reaction: Ag+(aq)+Cl(aq)AgCl(s) The two solutions were initially at 22.60C, and the final temperature is 23.40C Calculate the heat that accompanies this reaction in kJ/mol of AgCl formed. Assume that the combined solution has a mass of 100.0 g and a specific heat capacity of 4.18J/Cg.arrow_forwardA sample of ethanol, C2H5OH, weighing 2.84 g was burned in an excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rose from 25.00C to 33.73C. If the heat capacity of the calorimeter and contents was 9.63 kJ/C, what is the value of q for burning 1.00 mol of ethanol at constant volume and 25.00C? The reaction is C2H5OH(l)+3O2(g)2CO2(g)+3H2O(l) Is q equal to U or H?arrow_forward
- A sample of benzene, C6H6, weighing 3.51 g was burned in an excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rose from 25.00C to 37.18C. If the heat capacity of the calorimeter and contents was 12.05 kJ/C, what is the value of q for burning 1.00 mol of benzene at constant volume and 25.00C? The reaction is C6H6(l)+152O2(g)6CO2(g)+3H2O(l) Is q equal to U or H?arrow_forwardA 50-mL solution of a dilute AgNO3 solution is added to 100 mL of a base solution in a coffee-cup calorimeter. As Ag2O(s) precipitates, the temperature of the solution increases from 23.78 C to 25.19 C. Assuming that the mixture has the same specific heat as water and a mass of 150 g, calculate the heat q. Is the precipitation reaction exothermic or endothermic?arrow_forwardHow much heat is produced when loo mL of 0.250 M HCl (density, 1.00 g/mL) and 200 mL of 0.150 M NaOH (density, 1.00 g/mL) are mixed? HCl(aq)+NaO(aq)NaCl(aq)+H2O(l)H298=58kJ If both solutions are at the same temperature and the heat capacity of the products is 4.19 J/g C, how much will the temperature increase? What assumption did you make in your calculation?arrow_forward
- Consider the reaction 2HCl(aq)+Ba(OH)2(aq)BaCl2(aq)+2H2O(l)H=118KJ Calculate the heat when 100.0 rnL of 0.500 M HCl is mixed with 300.0 mL of 0.100 M Ba(OH)2 Assuming that the temperature of both solutions was initially 25.0C and that the final mixture has a mass of 400.0 g and a specific heat capacity of 4.18 J/C g, calculate the final temperature of the mixture.arrow_forwardGasohol, a mixture of gasoline and ethanol, C2H5OH, is used as automobile fuel. The alcohol releases energy in a combustion reaction with O2. C2H5OH(l)+3O2(g)2CO2(g)+3H2O(l) If 0.115 g ethanol evolves 3.62 kJ when burned at constant pressure, calculate the combustion enthalpy for ethanol.arrow_forwardThe head of a strike anywhere match contains tetraphosphorus trisulfide, P4S3. In an experiment, a student burned this compound in an excess of oxygen and found that it evolved 3651 kJ of heat per mole of P4S3 at a constant pressure of 1 atm. She wrote the following thermochemical equation: P4S3(s)+8O2(g)P4O10(s)+3SO2(g);H=3651kJ Calculate the standard enthalpy of formation of P4S3, using this students result and the following standard enthalpies of formation: P4O10(s), 3009.9 kJ/mol; SO2(g), 296.8 kJ/mol. How does this value compare with the value given in Appendix C?arrow_forward
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