Chemical energy is released or absorbed from reactions in various forms. The most easily measurable form of energy comes in the form of heat, or enthalpy for isobaric processes. The enthalpy of a reaction can be calculated from the heats of formation/ formation enthalpies of the substances involved in the reaction: AHAH (products) - AH; (reactants) ▾ Part A Calculate the standard enthalpy change for the reaction Use the following data: AH₂ Substance (kJ/mol) A B C D -225 -393 ΔΗ» = 209 -491 Express your answer to three significant figures and include the appropriate units. ▸ View Available Hint(s) HA Value Units ? 2A + B 2C + 2D

Chemical energy is released or absorbed from reactions in various forms. The most easily measurable form of energy comes in the form of heat, or enthalpy for isobaric processes. The enthalpy of a reaction can be calculated from the heats of formation/ formation enthalpies of the substances involved in the reaction: AHAH (products) - AH; (reactants) ▾ Part A Calculate the standard enthalpy change for the reaction Use the following data: AH₂ Substance (kJ/mol) A B C D -225 -393 ΔΗ» = 209 -491 Express your answer to three significant figures and include the appropriate units. ▸ View Available Hint(s) HA Value Units ? 2A + B 2C + 2D

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

See similar textbooks

Similar questions

When chemical A and chemical B are mixed together, and endothermic reaction below occurs:4A(aq) + 3B(s) --> 2C(aq)To find the enthalpy of this reaction, a scientist pours 155 mL of a 0.33 M solution A into abeaker and measures the temperature to be 20.1 ̊C. To this same beaker the scientist thenadds 3.75 g of substance B with stirring (molar mass of B is 33 g/mol), and finds thetemperature to now be 16.3 ̊C. Calculate the molar enthalpy of this reaction for every mole ofC produced.
In this experiment you will place a sample of your salt in water in a constant pressure calorimeter. You will determine the enthalpy change for the dissociation of your salt, Delta Hdiss. A sample of 4.368 grams of the salt SrCl2 was placed in 35.5 g water, the initial temperature was 20.00℃ and the final temperature was 27.086365℃. What is the number of moles of SrCl2? 4.368 g SrCl2 x ( 1 mol SrCl2 / 123.073 g SrCl2 ) = 0.035491131 mol SrCl2 a. 0.035491 mol SrCl2 b. none of these c. 0.035 mol SrCl2 d. 0.03 mol SrCl2 e. 0.0355 mol SrCl2 f. 0.04 mol SrCl2 g. 0.035491131 mol SrCl2 h. 0.03549 mol SrCl2
o-phthalic acid, C8H6O4, is sometimes used as a calorimetric standard. Its heat ofcombustion is - 3.224 × 103 kJ/mol C8H6O4. From the following data determine theheat capacity of a bomb calorimeter assembly (i.e., of the bomb, water, stirrer,thermometer, wires, etc.)mass of o-phthalic acid burned: 1.078 ginitial calorimeter temperature 24.96 °Cfinal calorimeter temperature 30.76 °C
Calcium acetate, Ca(CH3COO)2 has a molar mass of 158.17 g/mol. In a constant pressure calorimeter, 44.2 g of Ca(CH3COO)2 is dissolved in 861g of water at 25.00 °C. The heat produced by the solution was determined to be 15kJ. What is the final temperature of the solution? q= - msAT SH20 = 4.184 29.0 °C O 18.4 °C O 64.6 °C O 33.8 °C O 3.96 °C O 21.0 °C
None
7.Using the following standard enthalpies of reaction4NH3(g) + 7 O2(g) 4 NO2(g) + 6 H2O(l)H ̊rxn= -1395 kJN2(g) + 2 O22 NO2(g)H ̊rxn= +67.4 kJFind the standard enthalpy of reaction for the equation:2N2(g) + 6 H2O(l) 4 NH3(g) + 3 O2(g) Based on your work above, determine the standard enthalpy of reaction for the following equation:N2(g) + 3 H2O(l) 2 NH3(g) + 3/2 O2(g)
A scientist measures the standard enthalpy change for the following reaction to be 79.4 kJ:NH4Cl(aq)NH3(g) + HCl(aq)Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of HCl(aq) is kJ/mol.
The enthalpy of combustion of benzoic acid (C,H,COOH) is commonly used as the standard for calibrating constant-volume bomb calorimeters; its value has P mol been accurately determined to be -3226.7 - When 2.5311 g of benzoic acid are burned in a calorimeter, the temperature rises from 20.84 °C to 26.67 °C. What is the heat capacity of the bomb? (Assume that the quantity of water surrounding the bomb is exactly 2250 g) Round your answer to 3 significant digits. Note: Reference the Phase change properties of pure substances table for additional information. 0-/2 0.8 X 5 8 @ al P
A 3.450 g of propane (molar mass = 44.11 g/mol) was placed in a bomb calorimeter with excess oxygen and ignited. The initial temperature of the calorimeter was 24.000 degrees celsius and its total heat capacity was 76.65 kJ * C^-1. The reaction raised the temperature of the calorimeter to 28.965 degrees celsius. a. What is the heat exchangged by the reaction in kilojoules, qrxn? b. Calculate the deltaE rxn for the combustion of propane in kilojoules per mole c. Work in this reaction is done on the system, done on the surroundings, or equal to zero? Why?
The standard heat of formation, AH;, is defined as the enthalpy change for the formation of one mole of Part B substance from its constituent elements in their standard states. Thus, elements in their standard states have AH: = 0. Heat of formation values can be used The combustion of ethene, C2H4, occurs via the reaction to calculate the enthalpy change of any reaction. C2H4 (g) + 302 (g)→2CO2(g) + 2H20(g) Consider, for example, the reaction with heat of formation values given by the following table: 2NΟ (5) + Ο, (s) 2ΝO, (g) ΔΗρ (kJ/mol) Substance with heat of formation values given by the following table: C2H4 (g) 52.47 CO2 (g) -393.5 Substance (kJ/mol) H2O(g) -241.8 NO(g) 90.2 Calculate the enthalpy for the combustion of ethene. 02 (g) Express your answer to four significant figures and include the appropriate units. NO2(g) 33.2 • View Available Hint(s) Then the heat of formation for the overall reaction is ΔΗ ΔΗ (products) -ΔΗ; (reactants ) [2(90.2) + 0] HA ? 2(33.2) -114 kJ/mol…
A 25.0 mL portion of dilute HCl (aq) is combined with a 25.0 mL portion of dilute NaOH in a coffee-cup calorimeter. Both solutions are initially at a temperature of 23.3 ºC. The reaction produces enough heat to raise the final temperature of the 50.0 mL of liquid in the calorimeter to 25.3 ºC . What is qrxn in J? Assume the density of the reaction mixture is 1.0 g/mL and the specific heat of the solution is 4.184 J/g· ºC