Chemistry for Engineering Students
4th Edition
ISBN: 9781337398909
Author: Lawrence S. Brown, Tom Holme
Publisher: Cengage Learning
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Chapter 9, Problem 9.77PAE
9.77 When a reaction is exothermic, is the sum of bond energies of products or of reactants greater?
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Students have asked these similar questions
During the formation of a covalent bond, 2 nuclei, A and B, approach each other.
When A and B make a bond:
The potential energy of the system will be at a minimum or a maximum?
The bond energy will be released or required?
When the bond between A and B is broken:
The process is exothermic or endothermic?
If instead A forms a bond with C, and the bond length is shorter than the A-B bond, which is stronger?
A-B bond or A-C bond?
What is the total bond enthalpy for the molecule CHCI:? The following
bond enthalpies, in kJ/mol, are given: Cl-CI = 242, C-H = 413, C-CI = 328,
H-CI = 431. *
1397 kJ/mol
1172 kJ/mol
915 kJ/mol
1894 kJ/mol
8) In an exothermic reaction, the enthalpy of the reaction can be calculated by
a. Subtracting the sum of all the bond energies of the
products from the sum of all the bond energies of the
reactants.
b. Subtracting the sum of all the bond energies of the reactants
from the sum of all the bond energies of the products
c. Finding the sum of the enthalpies of formation of all the
products and reactants together d. All of the above
Chapter 9 Solutions
Chemistry for Engineering Students
Ch. 9 - Explain the economic importance of conversions...Ch. 9 - • define work and beat using the standard sign...Ch. 9 - • define state functions and explain their...Ch. 9 - • state the first law of thermodynamics in words...Ch. 9 - • use calorimetric data to obtain values for E and...Ch. 9 - • define Hfo and write formation reactions for...Ch. 9 - • explain Hess’s law in your own words.Ch. 9 - • calculate H for chemical reactions from...Ch. 9 - Prob. 9.1PAECh. 9 - Prob. 9.2PAE
Ch. 9 - Prob. 9.3PAECh. 9 - Prob. 9.4PAECh. 9 - Prob. 9.5PAECh. 9 - Prob. 9.6PAECh. 9 - Define the term internal energy.Ch. 9 - How fast (in meters per second) must an iron ball...Ch. 9 - What is the kinetic energy of a single molecule of...Ch. 9 - 9.10 The kinetic energy of molecules is often used...Ch. 9 - 9.11 Analyze the units of the quantity...Ch. 9 - 9.12 How many kilojoules are equal to 3.27 L atm...Ch. 9 - Prob. 9.13PAECh. 9 - Prob. 9.14PAECh. 9 - 9.15 Carry out the following conversions of energy...Ch. 9 - 9.16 According to Figure 9.2, the total energy...Ch. 9 - 9.17 If a machine does 4.8103kJ of work after an...Ch. 9 - 9.18 Calculate (a) q when a system does 54J of...Ch. 9 - 9.19 If the algebraic sign of E is negative, in...Ch. 9 - 9.20 State the first law of thermodynamics briefly...Ch. 9 - 9.21 Which type of energy heat or work, is valued...Ch. 9 - 9.12 PV-work occurs when volume changes and...Ch. 9 - 9.23 Which system does not work: (a) E=436J ,...Ch. 9 - 9.29 In which case is heat added to the system:...Ch. 9 - Prob. 9.25PAECh. 9 - 9.26 Gas furnaces have achieved impressive...Ch. 9 - Prob. 9.27PAECh. 9 - 9.28 When an electrical appliance whose power...Ch. 9 - Prob. 9.29PAECh. 9 - 9.30 For the example of shallow water and sandy...Ch. 9 - 9.31 A metal radiator is made from 26.0 kg of...Ch. 9 - 9.32 The material typically used to heat metal...Ch. 9 - 9.33 Copper wires used to transport electrical...Ch. 9 - 9.34 A copper nail and an iron nail of the same...Ch. 9 - 9.35 A piece of titanium metal with a mass of 20.8...Ch. 9 - 9.36 Define the term calibration.Ch. 9 - 9.37 A calorimeter contained 75.0 g of water at...Ch. 9 - 9.38 The energy densities of various types of coal...Ch. 9 - 9.39 How much thermal energy is required to heat...Ch. 9 - Prob. 9.40PAECh. 9 - 9.41 Under what conditions does the enthalpy...Ch. 9 - 9.42 Why is enthalpy generally more useful than...Ch. 9 - Prob. 9.43PAECh. 9 - Prob. 9.44PAECh. 9 - 9.45 What happens to the temperature of a material...Ch. 9 - 9.46 The heat of fusion of pure silicon is 43.4...Ch. 9 - 9.47 If 14.8 kJ of heat is given off when 1.6 g of...Ch. 9 - 9.48 Calculate the energy required to convert 1.70...Ch. 9 - 9.49 Hvap=31.3 kJ/mol for acetone. If 1.40 kg of...Ch. 9 - 9.50 When a 13.0-g sample of NaOH(s) dissolves in...Ch. 9 - Prob. 9.51PAECh. 9 - 9.52 Write the formation reaction for each of the...Ch. 9 - 9.53 Using these reactions, find the standard...Ch. 9 - 9.54 The phase change between graphite and diamond...Ch. 9 - 9.55 Hydrogen gas will react with either acetylene...Ch. 9 - 9.56 Using heats of formation tabulated in...Ch. 9 - 9.57 The heat of combustion of butane is —2877...Ch. 9 - 9.58 For the reaction C2H2(g)+2H2(g)C2H6,H=136 kJ....Ch. 9 - 9.59 For the reaction N2(g)+O2(g)2NO(g),H=180.5kJ...Ch. 9 - 9.60 Nitroglycenne, C3H5(NO3)3( l ), is an...Ch. 9 - 9.61 Silane, SiH4, burns according to the...Ch. 9 - 9.62 Sulfur trioxide can be removed from the...Ch. 9 - 9.63 Reactions of hydrocarhons are often studied...Ch. 9 - Prob. 9.64PAECh. 9 - 9.65 When 0.0157 g of a compound with a heat of...Ch. 9 - Prob. 9.66PAECh. 9 - Prob. 9.67PAECh. 9 - 9.68 What are some features of petroleum that make...Ch. 9 - 9.69 How are the roles of transmission substations...Ch. 9 - 9.70 Residential electric service in the United...Ch. 9 - 9.71 In recent years, the notion of a “smart grid”...Ch. 9 - 9.72 Although it can be a nuisance when a laptop...Ch. 9 - 9.73 Without looking up any numerical data or...Ch. 9 - 9.74 Without looking up any numerical data or...Ch. 9 - 9.75 Explain why each of the following chemical...Ch. 9 - 9.76 Which of the following are state functions?...Ch. 9 - 9.77 When a reaction is exothermic, is the sum of...Ch. 9 - Prob. 9.78PAECh. 9 - Prob. 9.79PAECh. 9 - Prob. 9.80PAECh. 9 - 9.81 A substance has the following properties:...Ch. 9 - 9.82 The specific heat of gold is 0.13 J g-1 K-1...Ch. 9 - 9.83 A student performing a calorimetry experiment...Ch. 9 - 9.84 Some claim it would be more logical to use...Ch. 9 - 9.85 The figure below shows a "self-cooling"...Ch. 9 - 9.86 You make some iced tea by dropping 134 g of...Ch. 9 - 9.87 What will be the final temperature of a...Ch. 9 - Prob. 9.88PAECh. 9 - 9.89 A sample of gas is 80.0% CH4 and 20.0% C2H6...Ch. 9 - 9.90 Many engineering designs must incorporate...Ch. 9 - 9.91 You want to heat the air in your house with...Ch. 9 - Prob. 9.92PAECh. 9 - Prob. 9.93PAECh. 9 - Prob. 9.94PAECh. 9 - 9.95 How much heat is required to convert 250 g of...Ch. 9 - 9.96 Most first aid "cold packs" are based on the...Ch. 9 - 9.97 Suppose that the working fluid inside an...Ch. 9 - 9.98 Hydrogen combines with oxygen in fuel cells...Ch. 9 - 9.99 The chemical reaction...Ch. 9 - 9.100 Two baking sheets are made of different...Ch. 9 - Prob. 9.101PAECh. 9 - 9.102 A runner generates 418 kJ of energy per...Ch. 9 - 9.103 One reason why the energy density of a fuel...Ch. 9 - 9.104 An engineer is using sodium metal as a...Ch. 9 - Prob. 9.105PAECh. 9 - Prob. 9.106PAECh. 9 - Prob. 9.107PAECh. 9 - Prob. 9.108PAECh. 9 - Prob. 9.109PAECh. 9 - Prob. 9.110PAE
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.Similar questions
- Explain the decomposition of nitroglycerin in terms of relative bond enthalpies.arrow_forwardA commercial process for preparing ethanol (ethyl alcohol), C2H5OH, consists of passing ethylene gas. C2H4, and steam over an acid catalyst (to speed up the reaction). The gas-phase reaction is Use bond enthalpies (Table 9.5) to estimate the enthalpy change for this reaction when 37.0 g of ethyl alcohol is produced.arrow_forwardhat is the enthalpy change for a process? Is enthalpy a state function? In what experimental apparatus are enthalpy changes measured?arrow_forward
- Calculate the enthalpy of reaction for HCN(g)H(g)+C(g)+N(g) from enthalpies of formation (see Appendix C). Given that the CH bond enthalpy is 411 kJ/mol, obtain a value for the CN bond enthalpy. Compare your result with the value given in Table 9.5.arrow_forwardWhich statement(s) is/are true about bond enthalpy? (a) The bond energy for a triple bond between A and B is three times that of a single bond between A and B. (b) H for the breaking of a bond is always a negative number. (c) Energy is required to make a bond. (d) Bond enthalpy is defined only for bonds broken or formed in the gaseous state. (e) The presence of bonds does not influence the geometry of a molecule. However, the presence of bonds affects the value of the bond enthalpy between two atoms.arrow_forwardCompare your answers from parts a and b of Exercise 69 of Chapter 3 with H values calculated for each reaction using standard enthalpies of formation in Appendix 4. Do enthalpy changes calculated from bond energies give a reasonable estimate of the actual values?arrow_forward
- Given the following data: NO2(g) NO(g) + O(g)H = 233 kJ 2O3(g) 3O2(g)H = 427 kJ NO(g) + O3(g) NO2(g) + O2(g)H = 199 kJ Calculate the bond energy for the O2 bond, that is, calculate H for: O2(g) 2O(g)H = ?arrow_forwardDraw a curve that describes the energy of a system with H and Cl atoms at varying distances. Then, find the minimum energy of this curve two ways. (a) Use the bond energy found in Table 8.1 to calculate the energy for one single HCl bond (Hint: How many bonds are in a mole?) (b) Use the enthalpy of reaction and the bond energies for H2 and Cl2 to solve for the energy of one mole of HCl bonds. H2(g)+Cl2(g)2HCl(g)Hrxn=184.7kJ/molarrow_forwardBond Enthalpy When atoms of the hypothetical element X are placed together, they rapidly undergo reaction to form the X2 molecule: X(g)+X(g)X2(g) a Would you predict that this reaction is exothermic or endothermic? Explain. b Is the bond enthalpy of X2 a positive or a negative quantity? Why? c Suppose H for the reaction is 500 kJ/mol. Estimate the bond enthalpy of the X2 molecule. d Another hypothetical molecular compound, Y2(g), has a bond enthalpy of 750 kJ/mol, and the molecular compound XY(g) has a bond enthalpy of 1500 kJ/mol. Using bond enthalpy information, calculate H for the following reaction. X2(g)+Y2(g)2XY(g) e Given the following information, as well as the information previously presented, predict whether or not the hypothetical ionic compound AX is likely to form. In this compound, A forms the A+ cation, and X forms the X anion. Be sure to justify your answer. Reaction: A(g)+12X2(g)AX(s)The first ionization energy of A(g) is 400 kJ/mol. The electron affinity of X(g) is 525 kJ/mol. The lattice energy of AX(s) is 100 kJ/mol. f If you predicted that no ionic compound would form from the reaction in Part e, what minimum amount of AX(s) lattice energy might lead to compound formation?arrow_forward
- Estimate H for the following reactions using bond energies given in Table 8.5. 3CH2=CH2(g) + 3H2(g) 3CH2CH3(g) The enthalpies of formation for C6H6(g) and C6H12 (g) are 82.9 and 90.3 kJ/mol. respectively. Calculate H for the two reactions using standard enthalpies of formation from Appendix 4. Account for any differences between the results obtained from the two methods.arrow_forwardExplain how bond energies can be used to estimate E for a reaction. Why is this an estimate of E? How do the product bond strengths compare to the reactant bond strengths for a reaction that releases energy? A reaction that gains energy? What is the relationship between the number of bonds between two atoms and bond strength? Bond length?arrow_forwardUsing the bond energies in Table 7.2, determine the approximate enthalpy change for each of the following reactions: (a) Cl2(g)+3F2(g)2ClF3(g) (b) H2C=CH2(g)+H2(g)H3CCH3(g) (c) 2C2H6(g)+7O2(g)4CO2(g)+6H2O(g) .arrow_forward
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