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Thermochemistry – HW PSI Chemistry Name Energy 1 - NJCTL

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Thermochemistry – HW
PSI Chemistry
Name _____________________________
Energy
1) Objects can possess energy as:
(a) endothermic energy (b) potential energy
A) a only
B) b only
C) c only
D) a and c
E) b and c
(c) kinetic energy
2) The internal energy of a system
A) is the sum of the kinetic energy of all of its components
B) is the sum of the rotational, vibrational, and translational energies of all of its
components
C) refers only to the energies of the nuclei of the atoms of the component molecules
D) is the sum of the potential and kinetic energies of the components
E) none of the above
3) Which one of the following conditions would always result in an increase in the internal
energy of a system?
A) The system loses heat and does work on the surroundings.
B) The system gains heat and does work on the surroundings.
C) The system loses heat and has work done on it by the surroundings.
D) The system gains heat and has work done on it by the surroundings.
E) None of the above is correct.
4) The value of О”E for a system that performs 111 kJ of work on its surroundings and gains
89 kJ of heat is __________ kJ.
A) -111
B) -200
C) 200
D) -22
E) 22
5) The value of О”E for a system that performs 13 kJ of work on its surroundings and loses 9
kJ of heat is __________ kJ.
A) 22
B) -22
C) -4
D) 4
E) -13
6) Calculate the value of О”E in joules for a system that loses 50 J of heat and has 150 J of
work performed on it by the surroundings.
A) 50
B) 100
C) -100
D) -200
E) +200
7) The change in the internal energy of a system that absorbs 2,500 J of heat and that does
7,655 J of work on the surroundings is __________ J.
A) 10,155
B) 5,155
C) -5,155
D) -10,155
E) 1.91 x107
8) The change in the internal energy of a system that releases 2,500 J of heat and that does
7,655 J of work on the surroundings is __________ J.
A) -10,155
B) -5,155
C) -1.91x107
D) 10,155
E) 5,155
9) When a system __________, О”E is always negative.
A) absorbs heat and does work
B) gives off heat and does work
C) absorbs heat and has work done on it
D) gives off heat and has work done on it
E) none of the above is always negative.
10) Of the following, which one is a state function?
A) H
B) q
C) w
D) heat
E) none of the above
Energy Changes
11) Which one of the following is an endothermic process?
A) ice melting
B) water freezing
C) boiling soup
D) Hydrochloric acid and barium hydroxide are mixed at 25 В°C: the temperature
increases. E) Both A and C
12) Which one of the following is an exothermic process?
A) ice melting
B) water evaporating
C) boiling soup
D) condensation of water vapor
E) Ammonium thiocyanate and barium hydroxide are mixed at 25 В°C: the temperature
drops.
13) A __________ О”H corresponds to an __________ process.
A) negative, endothermic
B) negative, exothermic
C) positive, exothermic
D) zero, exothermic
E) zero, endothermic
14) A __________ О”H corresponds to an __________ process.
A) negative, endothermic
B) positive, exothermic
C) positive, endothermic
D) zero, exothermic
E) zero, endothermic zero, endothermic
15) О”H for an endothermic process is _____ while О”H for an exothermic process is _______.
A) zero, positive
B) zero, negative
C) positive, zero
D) negative, positive
E) positive, negative
16) A chemical reaction that absorbs heat from the surroundings is said to be __________
and has a __________ О”H.
A) endothermic, positive
B) endothermic, negative
C) exothermic, negative
D) exothermic, positive
E) exothermic, neutral
17) The reaction 4Al(s) + 3O2 (g) пѓ 2Al2O3 (s)
О”HВ° = -3351 kJ
is __________, and therefore heat is __________ by the reaction.
A) endothermic, released
B) endothermic, absorbed
C) exothermic, released
D) exothermic, absorbed
E) thermoneutral, neither released nor absorbed
Calorimetry
*18) The molar heat capacity of a compound with the formula C H SO is 88.0 J/mol-K. The
2
6
specific heat of this substance is __________ J/g-K.
A) 88.0
B) 1.13
C) 4.89
D) 6.88x103
E) -88.0
19) A sample of aluminum metal absorbs 9.86 J of heat, and the temperature of the sample
increases from 23.2 В°C to 30.5 В°C. Since the specific heat capacity of aluminum is 0.90 J/gK, the mass of the sample is __________ g.
A) 72
B) 1.5
C) 65
D) 8.1
E) 6.6
20) The specific heat capacity of lead is 0.13 J/g-K. How much heat (in J) is required to raise
the temperature of 15g of lead from 22 В°C to 37 В°C?
A) 2.0
B) -0.13
C) 5.8 x10-4
D) 29
E) 0.13
21) The temperature of a 15-g sample of lead metal increases from 22 В°C to 37 В°C upon the
addition of 29.0 J of heat. The specific heat capacity of the lead is __________ J/g-K.
A) 7.8
B) 1.9
C) 29
D) 0.13
E) -29
*22) The О”H for the solution process when solid sodium hydroxide dissolves in water is 44.4
kJ/mol. When a 13.9-g sample of NaOH dissolves in 250.0 g of water in a coffee-cup
calorimeter, the temperature increases from 23.0 В°C to __________ В°C. Assume that the
solution has the same specific heat as liquid water, i.e., 4.18 J/g-K.
A) 35.2 В°C
B) 24.0 В°C
C) 37.8 В°C
D) 37.0 В°C
E) 40.2 В°C
23) An 8.29 g sample of calcium carbonate [CaCO3(s)] absorbs 50.3 J of heat, upon which
the temperature of the sample increases from 21.1 В°C to 28.5 В°C. What is the specific heat of
calcium carbonate?
A) .63
B) .82
C) 1.1
D) 2.2
E) 4.2
24) A sample of iron absorbs 67.5 J of heat, upon which the temperature of the sample
increases from 21.5 В°C to 28.5 В°C. If the specific heat of iron is 0.450 J/g-K, what is the mass
(in grams) of the sample?
A) 4.3
B) 11
C) 21
D) 1100
E) 1.1x 103
25) A 22.44 g sample of iron absorbs 180.8 J of heat, upon which the temperature of the
sample increases from 21.1 В°C to 39.0 В°C. What is the specific heat of iron?
A) 0.140
B) 0.450
C) 0.820
D) 0.840
E) 0.900
26) When 45 g of an alloy at 1000C is dropped into 100.0 g of water at 25В°C, the final
temperature is 37В°C. What is the specific heat of the alloy (J/goC)? 31) ______
A)9.88
B) 48.8
C) 0.423
D) 1.77
*27) A 50.0-g sample of liquid water at 25.0 C is mixed with 29.0 g of water at 45.0 В°C. The
final temperature of the water is __________.
A) 102
B) 27.6
C) 35.0
D) 142
E) 32.3
28) A 6.50-g sample of copper metal at 25.0 В°C is heated by the addition of 84.0 J of energy.
The final temperature of the copper is _____ В°C. The specific heat of copper is 0.38 J/g-K
A) 29.9
B) 25.0
C) 9.0
D) 59.0
E) 34.0
Heating curves
29) How much heat is required to melt 1.5 moles of NaCl at its melting point (пЃ„Hfus = 30
kJ/mol)
A) 1.5 kJ
B) 15 kJ
C) 20 kJ
D) 30 kJ
E) 45 kJ
30) A substance releases 500 kJ of heat as 25 mol of it condenses from a gas to a liquid .
What is the heat of vaporization (пЃ„Hvap) of this substance?
A) 20 kJ/mol
B) 25 kJ/mol
C) 475 kJ/mol
D) 525 kJ/mol
**31) If you supply 36 kJ of heat, how many moles of ice a 0 C can be melted, heated to its
o
boiling point and completely boiled away?
пЃ„Hvap = 40.5 kJ/mol; пЃ„Hfus = 6.0 kJ/mol; specific heat for water, C = 0.0753 kJ/mol-oC
**32) Given the equation:
H2O (l) пѓ H2O(g)
пЃ„Hrxn = 40.7 kJ at 100 п‚°C
Calculate the mass of liquid water (in grams) at 100 п‚°C that can converted to vapor by
absorbing 2.40 kJ of heat.
33) Given the equation: H2O (l) пѓ H2O(g)
пЃ„Hrxn = 40.7 kJ at 100 п‚°C
Calculate the heat required to convert 3.00 grams of liquid water at 100 В°C to vapor.
*34) Based on the following information, which compound has the strongest intermolecular
forces?
Substance
Argon (Ar)
Benzene ( C 6 H 6 )
Ethanol ( C 2 H 5OH )
Water ( H 2 O )
О”Hvap (kJ/mol)
6.3
31.0
39.3
40.8
Methane ( CH 4 )
A) Argon
B) Benzene
C) Ethanol
D) Water
E) Methane
9.2
Use the information in this table to answer the next four questions.
Specific heat of ice
Specific heat of water
Specific heat of steam
Heat of fusion of water ( пЃ„ Hfus)
2.09 J/g-oC
4.18 J/g-oC
1.84 J/g-oC
6.01 kJ/mol
Heat of vaporization of water ( пЃ„ Hvap)
40.7 kJ/mol
35) What amount of heat (in kJ) is required to melt 35.0 g of ice at 0 oC?
A) 3.09 kJ
B) 11.7 kJ
C) 20.9 kJ
D) 79.1 kJ
36) What amount of heat (in kJ) is required to completely convert 190.0 g of liquid water at
18oC to steam at 100.0oC?
A) 6.51 kJ
B) 6.94 kJ
C) 430 kJ
D) 559 kJ
37) The enthalpy change for converting 1.00 mol of ice at -50.0 В°C to water at 70.0 В°C is
________kJ.
A) 12.28
B) 6.41
C) 13.16
D) 7154
E) 9.40
38) The enthalpy change for converting 10.0 g of ice at -25.0 В°C to water at 80.0 В°C is
__________ kJ.
A) 12.28
B) 6.16
C) 3870
D) 7.21
E) 9.88
**39) The heat of fusion of water is 6.01 kJ/mol. The heat capacity of liquid water is 75.3
J/mol-K The conversion of 50.0 g of ice at 0.00 В°C to liquid water at 22.0 В°C requires
__________ kJ of heat.
A) 3.8 x102
B) 21.3
C) 17.2
D) 0.469
E) Insufficient data are given.
Enthalpy
40) Which of the following statements is false?
A) Internal energy is a state function.
B) Enthalpy is an intensive property.
C) The enthalpy change for a reaction is equal in magnitude, but opposite in sign, to
the enthalpy change for the reverse reaction.
D) The enthalpy change for a reaction depends on the state of the reactants and
products.
E) The enthalpy of a reaction is equal to the heat of the reaction.
41) The value of пЃ„H0 for the reaction below is -72 kJ. __________ kJ of heat are released
when 1.0 mol of HBr is formed in this reaction: H2(g) + Br2 (g) пѓ 2HBr(g)
A) 144
B) 72
C) 0.44
D) 36
E) -72
42) The value of пЃ„H0 for the reaction below is -126 kJ. __________ kj are released when
2.00 mol of NaOH is formed in the reaction? 2Na2O2(s) + 2H2O(l) пѓ 4NaOH(s) + O2(g)
A) 252
B) 63
C) 3.9
D) 7.8
E) -126
43) The value of пЃ„H0 for the reaction below is -790 kJ. The enthalpy change accompanying
the reaction of 0.95 g of S is __________ kJ. 2S(s) + 3O2 (g) пѓ 2SO3(g)
A) 23
B) -23
C) -12
D) 12
E) -790
44) The value of пЃ„H0 for the reaction below is -6535 kJ. __________ kJ of heat are released
in the combustion of 16.0 g of C6H6(l)? 2C6H6(l) + 15O2 (g) пѓ 12CO2 (g) + 6H2O(l)
A) 1.34 x 103
B) 5.23 x014
C) 669
D) 2.68 x103
E) -6535
45) The value of пЃ„H0 for the reaction below is -482 kJ. Calculate the heat (kJ) released to
the surroundings when 12.0 g of CO (g) reacts completely. 2CO(g) + O2(g) пѓ 2CO2(g)
A) 2.89x103
B) 207
C) 103
D) 65.7
E) -482
46) The value of пЃ„H0 for the reaction below is -336 kJ. Calculate the heat (kJ) released to
the surroundings when 23.0 g of HCl is formed. CH4(g) +3Cl2 (g) пѓ CHCl3(l) + 3HCl(g)
A) 177
B) 2.57x103
C) 70.7
D) 211
E) -336
47) The value of пЃ„H0 for the reaction below is -186 kJ. Calculate the heat (kJ) released from
the reaction of 25 g of Cl2. H2 (g) + Cl2 (g) пѓ 2HCl (g)
A) 66
B) 5.3x102
C) 33
D) 47
E) -186
48) The enthalpy change for the following reaction is -483.6 kJ: 2H2 (g) + O2 (g) пѓ 2H2O(g)
Therefore, the enthalpy change for the following reaction is __________ kJ:
4H2 (g) + 2O2 (g) пѓ 4H2O(g)
A) -483.6
B) -967.2
C) 2.34x105
D) 483.6
E) 967.2
49) The value of пЃ„HВ° for the reaction below is +128.1 kJ: CH3OH (l) пѓ CO(g) + 2H2(g)
How many kJ of heat are consumed when 15.5 g of CH3OH(l) decomposes as shown in the
equation?
A) 0.48
B) 62.0
C) 1.3x102
D) 32
E) 8.3
50) The value of пЃ„H0 for the reaction below is +128.1 kJ: CH3OH (l) пѓ CO(g) + 2H2(g)
How many kJ of heat are consumed when 5.10 g of H2(g) is formed as shown in the
equation?
A) 162
B) 62.0
C) 128
D) 653
E) 326
51) The value of пЃ„H0 for the reaction below is +128.1 kJ: CH3OH (l) пѓ CO(g) + 2H2(g)
How many kJ of heat are consumed when 5.10 g of CO (g) are formed?
A) 0.182
B) 162
C) 8.31
D) 23.3
E) 62.0
52) The value of пЃ„H0 for the reaction below is +128.1 kJ: CH3OH (l) пѓ CO(g) + 2H2(g)
How many kJ of heat are consumed when 5.75 g of CO(g) is formed?
A) 23.3
B) 62.0
C) 26.3
D) 162
E) 8.3
53) The value of пЃ„H0 for the reaction below is -1107 kJ: 2Ba(s) + O2 (g) пѓ 2BaO (s)
How many kJ of heat are released when 5.75 g of Ba(s) reacts completely with oxygen to
form BaO(s)?
A) 96.3
B) 26.3
C) 46.4
D) 23.2
E) 193
54) The value of пЃ„H0 for this reaction is -1107 kJ: 2Ba(s) + O2 (g) пѓ 2BaO (s)
How many kJ of heat are released when 5.75 g of BaO(s) is produced?
A) 56.9
B) 23.2
C) 20.8
D) 193
E) 96.3
55) The value of пЃ„H0 for the reaction below is -1107 kJ: 2Ba(s) + O2 (g) пѓ 2BaO (s)
How many kJ of heat are released when 15.75 g of Ba(s) reacts completely with oxygen to
form BaO(s)?
A) 20.8
B) 63.5
C) 114
D) 70.3
E) 35.1
Hess’ Law of Heat Summation
56) Which of the following is a statement of Hess's law?
A) If a reaction is carried out in a series of steps, the О”H for the reaction will equal the
sum of the enthalpy changes for the individual steps.
B) If a reaction is carried out in a series of steps, the О”H for the reaction will equal the
product of the enthalpy changes for the individual steps.
C) The О”H for a process in the forward direction is equal in magnitude and opposite in
sign to the О”H for the process in the reverse direction.
D) The О”H for a process in the forward direction is equal to the О”H for the process in
the reverse direction.
E) The О”H of a reaction depends on the physical states of the reactants and products.
*57) О”H for the reaction IF (g) пѓ IF (g) + F (g) is __________ kJ, give the data below.
5
3
2
IF (g) + F2(g) пѓ IF3 (g) )
IF (g) + 2F2(g) пѓ IF5 (g)
О”H = -390 kJ
О”H = -745 kJ
A) +355
B) -1135
C) +1135
D) +35
E) -35
*58) Given the following reactions the enthalpy of the reaction of the nitrogen to produce
nitric oxide N2 (g) + O2(g) пѓ 2NO (g) is __________ kJ.
N2 (g) + 2O2(g) пѓ 2NO2 (g)
О”H = 66.4 kJ
2NO (g) + O2(g) пѓ 2NO2 (g)
О”H = -114.2 kJ
A) 180.6
B) -47.8
C) 47.8
D) 90.3
E) -180.6
*59) Given the following reactions the enthalpy of the reaction of nitrogen with oxygen to
produce nitrogen dioxide N2 (g) + 2O2(g) пѓ 2NO2 (g) is __________ kJ.
(1) 2NO пѓ N2 + O2
(2) 2NO + O2 пѓ 2NO2
О”H = -180 kJ
О”H = -112 kJ
A) 68
B) -68
C) -292
D) 292
E) -146
*60) Given the following reactions the enthalpy of the reaction
CaCO3 (s) пѓ CaO(s) + C (s) + O2 (g) is __________ kJ.
CaCO3 (s) пѓ CaO(s) + CO2(g)
C(s) + O2 (g) пѓ CO2(g)
A) 215.4
B) 571.6
C) -215.4
D) -571.6
E) 7.01x104
О”H = 178.1 kJ
О”H = -393.5 kJ
*61) Given the following reactions the enthalpy for the decomposition of liquid water into
gaseous hydrogen and oxygen 2H2O (l) пѓ 2H2 (g) + O2(g) is __________ kJ.
H2O (l) пѓ H2O (g)
О”H = 44.01 kJ
2H2 (g) O2(g) пѓ 2H2O (g)
О”H = -483.64 kJ
A) -395.62
B) -527.65
C) 439.63
D) 571.66
E) 527.65
*62) Given the following reactions the enthalpy for the decomposition of nitrogen dioxide into
molecular nitrogen and oxygen 2NO2 (g) пѓ N2(g) + 2O2 (g) is __________ kJ.
N2 (g) O2(g) пѓ 2NO(g)
О”H = +180.7 kJ
2NO (g) + O2 (g) пѓ 2NO2 (g)
О”H = -113.1 kJ
A) 67.6
B) -67.6
C) 293.8
D) -293.8
E) 45.5
*63) Given the following reactions the enthalpy of reaction for 4NO(g) пѓ 2NO (g) + N (g)
2
is ____ kJ.
N2 (g) + O2(g) пѓ 2NO (g)
2NO(g) +O2 (g) пѓ 2NO2 (g)
A) 67.6
B) 45.5
C) -293.8
D) -45.5
О”H = +180.7 kJ
О”H = -113.1 kJ
2
E) 293.8
*64) Given the following reactions the enthalpy of reaction for 2N O(g) пѓ 2NO(g) +N (g)
2
2
is __________ kJ.
О”H = +180.7 kJ
О”H = -163.2 kJ
N2 (g) + O2(g) пѓ 2NO(g)
2N2O(g) пѓ O2 (g) + 2N2(g)
A) 145.7
B) 343.9
C) -343.9
D) 17.5
E) -145.7
Heats of Formation
65) Of the following, О”Hf0 is not zero for __________.
A) O2(g)
B) C (graphite)
C) N2(g)
D) F2 (s)
E) Cl2(g)
66) In the reaction below, О”Hf0 is zero for __________.
Ni(s) + 2CO (g) +2PF3 (g) пѓ Ni(CO)2 (PF3)2(l)
A) Ni(s)
B) CO(g)
C) PF3(g)
D) Ni(CO)2 (PF3)2(l)
E) both CO and PF3
67) For the species in the reaction below, О”Hf0is zero for __________.
2Co(s) + H2(g) + 8PF3 (g) пѓ 2HCo(PF3)4 (I)
A) Co(s)
B) H2(g)
C) PF3 (g)
D) HCo(PF3)4
E) both Co(s) and H2(g)
**68) For which one of the following equations is
О”H0 rxn equal to О”Hf0 for the product?
A) Xe (g) + 2F2 (g) пѓ XeF4 (g)
B) CH4 (g) +2Cl2(g) пѓ CH2Cl2 (l) + 2HCl(g)
C) N2(g) + O3 (g) пѓ N2O3 (g)
D) 2CO(g) +O2(g) пѓ 2CO2
E) C(diamond) + O2(g) пѓ CO2 (g)
**69) For which of the following reactions is the value of О”H rxn
0
for the product?
A) 2Ca(s) + O2 (g) пѓ 2CaO(s)
B) C2H2(g) + H2(g) пѓ C2H4 (g)
equal to О”Hf0
C) 2C(graphite) +O2(g) пѓ 2CO (g)
D) 3Mg(s) + N2(g) пѓ Mg3N2(s)
E) C(diamond) + O2(g) пѓ CO2 (g)
**70) For which of the following reactions is the value of О”H rxn
0
equal to О”Hf0 for the
product?
A) 2C(graphite) + 2H2(g) пѓ C2H4(g)
B) N2(g) +O2(g) пѓ 2NO(g)
C) 2H2(g) +O2(g) пѓ 2H2O(l)
D) 2H2(g) + O2(g) пѓ 2H2O(g)
E) H2O(l) +1/2 O2(g) пѓ 2H2O(l)
71) For which of the following reactions is the value of О”H0 rxn equal to О”Hf0 for the product?
A) H2O(l) +1/2 O2(g) пѓ H2O2(l)
B) N2(g) +O2(g) пѓ 2NO(g)
C) 2H2(g) + O2(g) пѓ 2H2O(l)
D) 2H2(g) + O2(g) пѓ 2H2O(g)
E) none of the above
72) For which of the following reactions is the value of О”H0 rxn equal to О”Hf0 for the
product?
A) H2(g) + 1/2O2(g) пѓ H2O(l)
B) H2(g) + O2(g) пѓ H2O2 (l)
C) 2C(graphite) + 2H2(g) пѓ C2H4(g)
D) 1/2N2(g) + O2(g) пѓ NO2(g)
E) all of the above
73) The value of пЃ„Hп‚° for the reaction below is -186 kJ.
The value of О”Hf0 for HCl (g) is __________ kJ/mol.
A) -3.72x102
B) -1.27x102
C) -93.0
D) -186
E) +186
H2(g) + Cl2(g) пѓ 2HCl(g)
74) The value of пЃ„Hп‚° for the following reaction is -3351 kJ: 2Al(s) +3O2(g) пѓ 2Al2O3
The value of О”Hf0 for Al2O3 is __________ kJ.
A) -3351
B) -1676
C) -32.86
D) -16.43
E) +3351
75) Given the data in the table below, О”H0 rxn for this reaction is __________ kJ.
Ca(OH)2 + 2H3AsO4 пѓ Ca(H2AsO4)2 + 2H2O
Substance
О”Hf0 (kJ/mol)
Ca(OH)2
H3AsO4
Ca(H2AsO4)2
H2O
-986.6
-900.4
-2346.0
-285.9
A) -744.9
B) -4519
C) -4219
D) -130.4
E) -76.4
76) Given the data in the table below, О”H0 rxn for this reaction is __________ kJ.
4NH3 (g) + 5O2)g) пѓ 4NO(g) + 6H2O(l)
Substance
О”Hf0 (kJ/mol)
H2O(l)
NO (g)
NO2 (g)
HNO3 (aq)
NH3 (g)
-286
90
34
-207
-46
A) -1172
B) -150
C) -1540
D) -1892
E) The О”Hf0 of O 2 (g) is needed.
77) Given the data in the table below, О”H0 rxn for this reaction is __________ kJ.
C2H5OH(l) +O2(g) пѓ CH3CO2H(l) + H2O(l)
Substance
О”Hf0 (kJ /mol)
C2H4(g)
C2H5OH(l)
CH3CO2H(l)
H2O(l)
523
-277.7
-484.5
-285.8
A) -79.0
B) -1048.0
C) -476.4
D) -492.6
E) The value of О”Hf0 of O 2 (g) is required
78) Given the data in the table below, О”H0 rxn for this reaction is __________ kJ.
3NO2 +H2O (l) пѓ 2HNO3 (aq) + NO(g)
Substance
О”Hf0 (kJ/mol)
H2O(l)
NO (g)
NO2 (g)
HNO3 (aq)
NH3 (g)
A) 64
B) 140
C) -140
D) -508
E) -64
-286
90
34
-207
-46
79) Given the data in the table below, О”H0 rxn for this reaction is __________ kJ.
IF5(g) + F2(g) пѓ IF7(g)
Substance
IF(g)
IF5(g)
IF7(g)
О”Hf0 (kJ /mol)
-95
-840
-941
A) 1801
B) -1801
C) 121
D) -121
E) -101
80) Given the data in the table below, пЃ„Hп‚° for the reaction is __________ kJ.
2CO (g) + O2 пѓ 2CO2(g)
Substance
CO(g)
CO2(g)
CaCO3(s)
О”Hf0 (kJ /mol)
-110.5
-393.7
-1207.0
A) -566.4
B) -283.2
C) 283.2
D) -677.0
E) The О”Hf0 of O 2 (g) is needed
*81) The value of О”HВ° for the following reaction is 177.8 kJ. The value of О”H
f
0
for
CaO(s) is __________ kJ/mol.
CaCO3(s) пѓ CaO(s) + CO2(g)
Substance
CO(g)
CO2(g)
CaCO3(s)
О”Hf0 (kJ /mol)
-110.5
-393.7
-1207.0
A) -1600
B) -813.4
C) -635.5
D) 813.4
E) 177.8
82) Given the data in the table below, О”H0 rxn for the reaction is __________ kJ.
2Ag2S(s) +O2(g) пѓ 2Ag2O(s) +2S(s)
Substance
Ag2O(s)
Ag2S(s)
H2S(g)
H2O(l)
О”Hf0 (kJ /mol)
-31.0
-326
-20.6
-286
A) -1.6
B) +1.6
C) -3.2
D) +3.2
E) The О”Hf0 of S(s) and of O2(g) are needed.
83) Given the data in the table below, О”H0 rxn for the reaction is __________ kJ.
PCl3(g) +3HCl(g) пѓ 3Cl2(g) +PH3(g)
Substance
PCl3(g)
HCl(g)
PH3(g)
О”Hf0 (kJ /mol)
-288.07
-92.30
5.40
A) -570.37
B) -385.77
C) 570.37
D) 385.77
E) The О”Hf0 of Cl2(g) is needed for the calculation.
.
*84) Given the data in the table below and О”H rxn
0
for the reaction, О”Hf0 of HCl(g) is
__________ kJ/mol.
SO2Cl2(g) +2H2O(l) пѓ H2SO4(l) + 2HCl(g)
Substance
О”Hf0 (kJ /mol)
SO2(g)
-297
SO3(g)
-396
SO2Cl2(g) -364
H2SO4(l)
-814
H2O(l)
-286
A) -184
B) 60
C) -92
D) 30
E) Insufficient data are given.
О”Hf0 = -62 kJ
Answers
Energy
1) E
2) D
3) D
4) D
5) B
6) B
7) C
8) A
9) B
10) A
11) E
12) D
13) B
14) C
15) E
16) A
17) C
Calorimetry
18) B
19) B
20) D
21) D
22) D
23) B
24) C
25) B
26) D
27) E
28) D
Heating Curves
29) E
30) A
31) 0.67 mol water
32) 1.06 g
33) 6.78 kJ
34) D
35) B
36) D
37) C
38) D
39) B
Enthalpy
40) B
41) D
42) B
43) A
44) C
45) C
46) C
47) A
48) B
49) B
50) A
51) D
52) C
53) D
54) C
55) B
Hess’ Law
56) A
57) A
58) A
59) A
60) B
61) D
62) B
63) C
64) D
Heats of Formation
65) D
66) A
67) E
68) A
69) D
70) A
71) E
72) E
73) C
74) B
75) D
76) A
77) D
78) C
79) E
80) A
81) C
82) D
83) C
84) C
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