A sample of solid benzoic acid (C,H;COOH) that weighs 800 g is burned in an excess of oxygen to CO,(g) and H,O(€) in a constant-volume calorimeter at 25°C. The temperature increase is observed to be 2.15°C. The heat capacity of the calorimeter and its contents is known to be 9382 J K-1. (a) Write and balance the equation for the combustion of benzoic acid. (b) Calculate the standard change in internal energy (AU°) for the combustion of 1.000 mol benzoic acid to CO2(g) and H,O(€) at 25°C. lc) Calculate the standard enthalpy change (AH°) for the same reaction as in part (b). (d) Calculate the standard enthalpy of formation per mole of benzoic acid, using data for the standard enthalpies of formation of CO2(g) and H,O(() from Appendix D.

A sample of solid benzoic acid (C,H;COOH) that weighs 800 g is burned in an excess of oxygen to CO,(g) and H,O(€) in a constant-volume calorimeter at 25°C. The temperature increase is observed to be 2.15°C. The heat capacity of the calorimeter and its contents is known to be 9382 J K-1. (a) Write and balance the equation for the combustion of benzoic acid. (b) Calculate the standard change in internal energy (AU°) for the combustion of 1.000 mol benzoic acid to CO2(g) and H,O(€) at 25°C. lc) Calculate the standard enthalpy change (AH°) for the same reaction as in part (b). (d) Calculate the standard enthalpy of formation per mole of benzoic acid, using data for the standard enthalpies of formation of CO2(g) and H,O(() from Appendix D.

Physical Chemistry

2nd Edition

ISBN:9781133958437

Author:Ball, David W. (david Warren), BAER, Tomas

Publisher:Ball, David W. (david Warren), BAER, Tomas

Chapter2: The First Law Of Thermodynamics

Section: Chapter Questions

Problem 2.83E: Benzoic acid, C6H5COOH, is a common standard used in bomb calorimeters, which maintain a constant...

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Benzoic acid, C6H5COOH, is a common standard used in bomb calorimeters, which maintain a constant volume. If 1.20 g of benzoic acid gives off 31, 723 J of energy when burned in the presence of excess oxygen and in a water bath having a temperature of 24.6 C, calculate q, w, H, and U for the reaction.
Benzoic acid of mass 1.40 g is reacted with oxygen in a constant volume calorimeter to form H2O(l) and CO2(g) at 298 K. The mass of the water in the inner bath is 1.40×103g. The temperature of the calorimeter and its contents rises 2.84 K as a result of this reaction. Part A Calculate the calorimeter constant. The standard enthalpy of combustion of benzoic acid at 298 K is −3227 kJ⋅mol−1. CP,m(H2O,l)=75.3J⋅mol−1⋅K−1.
The complete combustion of solid fumaric acid, HOOCCH=CHCOOH, in a bomb calorimeter released 1333 kJ mol -1 of heat at 298 K. Calculate (a) the internal energy of combustion, (b) the enthalpy of combustion . (c) Usetabulated values for the standard enthalpy of formation of water and carbon dioxide to calculate the enthalpy of formation of solid fumaric acid.
A sample of the sugar d-ribose (C5H10O5) of mass 0.727 g was placed in a calorimeter and then ignited in the presence of excess oxygen. The temperature rose by 0.910 K. In a separate experiment in the same calorimeter, the combustion of 0.825 g of benzoic acid, for which the internal energy of combustion is −3251 kJ mol−1, gave a temperature rise of 1.940 K. Calculate the enthalpy of formation of d-ribose.
A) For nitrogen gas the values of Cv and Cp at 25°C are 20.8 J K−1 mol−1 and 29.1 J K−1 mol−1, respectively. When a sample of nitrogen is heated at constant pressure, what fraction of the energy is used to increase the internal energy of the gas? B) How much energy (in KJ) is required to raise the temperature of 136.4 g N2 from 25.0°C to 87.0°C in a vessel having a constant volume?
A sample of a serum of mass 26.6 g is cooled from 290 K to 275 K at constant pressure by the extraction of 1.05 kJ of energy as heat. Calculate q and ΔH and estimate the heat capacity of the sample. report here the heat capacity = ________ J/k/g. 3 sig. number
A laboratory animal exercised on a treadmill, which, through pulleys, raised a mass of 200 g through 1.55 m. At the same time, the animal lost 5.0 J of energy as heat. Disregarding all other losses and regarding the animal as a closed system, what is its change in internal energy?
Nitrogen gas stored in a flexible container expanded from a volume of 500 dm3 to a volume of 600 dm3 at a constant external pressure of 101.3 kPa upon absorbing 35.5 kJ of heat. How much is the change in the internal energy of the gas?
10.5 g of methanol was placed in a bomb calorimeter (with a known heat capacity of 0.874 kJ/K-1), together with 3.25 kg water with an initial temperature of 25.0oC. After methanol is combusted, what will the temperature of the water be, given that the standard enthalpy of combustion of methanol is deltacHo= – 715.0 kJ/mol–1?
When a sample of fructose (C6H12O6) weighing 0.2715 g was burned in a bomb calorimeter, the temperature rose from 22.15oC to 31.84oC. The heat capacity of the calorimeter was 436.6 J deg-1. Calculate (a) the molar internal energy of combustion (ΔCUo) and (b) the molar enthalpy of combustion (ΔCHo) of fructose. Ans: -2.81 x 103 kJ mol-1; -2.81 x 103 kJ mol-1
A sample of solid biphenyl weighing 0.5260 g was ignited in a bomb calorimeter initially at 25.0°C, producing a temperature rise of 1.910 K. Determine the internal energy (∆U) of combustion. To properly determine the internal energy of combustion for the solid biphenyl, the calorimeter was first calibrated. a)A 0.7750 g sample of benzoic acid (C₆H₅COOH, MW 122.1 g/mol)) was ignited under identical conditions and produced a temperature rise of 1.940 K. For benzoic acid, the internal energy combustion at constant volume, ∆U, is known to be –3226 kJ/mol. Calculate the calorimeter constant, in kJ/K. b)using the caloremeter constant, determine triangleU, in KJ/mol, for the conbustion of solid biphenyl ((C6H5)2, MW 154.21 g/mol)
a) A 1.60 dm3 sample of a mixture of methane gas, CH4 and oxygen gas, measured at 25 oC and 101 kPa, was allowed to react in a bomb calorimeter in which, had a heat capacity of 5.30 kJ/K altogether with its contents. The complete combustion of the methane gas to carbon dioxide gas and water caused a temperature rise in the calorimeter of 6.28 K. Given that ∆Ho c (CH4) is -560 kJ/mol. i. Define the standard enthalpy of combustion of methane ii. Write a thermochemical equation for the combustion of methane iii. Knowing the ∆Ho c of methane, calculate the number of mole of methane in the mixture. iv. Calculate the total moles of gases in the calorimeter.