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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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- 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
- The complete combustion of acetylene, C2H2(g), produces 1300. kJ of energy per mole of acetylene consumed. How many grams of acetylene must be burned to produce enough heat to raise the temperature of 1.00 gal water by 10.0c if the process is 80.0% efficient? Assume the density of water is 1.00 g/cm3arrow_forwardCalculate the standard enthalpy of combustion for benzene, C6H6. C6H6() + 15/2 O2(g) 6 CO2(g) + 3 H2O() rH = ? The enthalpy of formation of benzene is known [rH[C6H6()] = +49.0 kJ/mol], and other values needed can be found in Appendix L.arrow_forwardAnother reaction that is used to propel rockets is N2O4(l)+2N2H4(l)3N2(g)+4H2O(g) This reaction has the advantage that neither product is toxic, so no dangerous pollution is released. When the reaction consumes 10.0 g liquid N2O4, it releases 124 kJ of heat. (a) Is the sign of the enthalpy change positive or negative? (b) What is the value of H for the chemical equation if it is understood to be written in molar quantities?arrow_forward
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