GENERAL CHEMISTRY I
EXAM 4
Tuesday December 6, 1994

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1. How much heat is required to raise the temperature of 37.15 g H2O from 14.4 oC to 61.4 oC? The specific heat of H2O is 4.184 J/goC.
a) 1.50 kJb) 2.11 kJc) 4.18 kJd) 7.31 kJe) 8.85 kJ
2. Given the reaction

P4S3(s)    +    8O2(g)    ----->    P4O10(s)    +    3SO2(g)           DH = -3677 kJ

What is DH for the following reaction:

2P4S3(s)    +    16O2(g)    ----->    2P4O10(s)    +    6SO2(g)           DH = ?
a) 3677 kJb) -3677 kJc) 7354 kJd) -7354 kJ
e) -1839 kJ
3. What is DH for the following reaction:

H2(g)    +    O2(g)    ----->    H2O2(l)           DHrxn = ?

Make use of the following known thermochemical equations:

2H2O2(l)    ----->    2H2O(l)    +    O2(g)           DHrxn = -196.0 kJ

2H2(g)    +    O2(g)    ----->    2H2O(l)           DHrxn = -91.8 kJ
a) 52.1 kJb) -52.1 kJc) 287.8 kJd) -287.8 kJe) 104.2 kJ
4. The process in which calcium chloride, CaCl2, is dissolved in water is represented by the equation

CaCl2(s)    ----->    Ca2+(aq)    +    2Cl-(aq)

To determine the DH of this reaction, 23.60 g of CaCl2 was dissolved in water in a calorimeter. The heat capacity of the calorimeter and its contents was 1258 J/oC, and in the process of dissolving, the temperature rose from 25.00 oC to 38.70 oC. What is DH for the above reaction?
a) -21.17 kJb) 21.17 kJc) -46.53 kJd) 46.53 kJe) -81.05 kJ
5. Use standard enthalpies of formation (DHf values) to calculate DH of the following reaction:

CaCO3(s)    +    CO2(g)    +    H2O(l)    ----->    Ca2+(aq)    +    2HCO3-(aq)           DHrxn = ?

Note: The necessary DHf values can be found in Table 6.2, a copy of which is provided with this exam.
a) -3811.4 kJb) -83.0 kJc) -39.0 kJd) 561.0 kJe) 652.1 kJ
Note: This test refers to Table 6.2 in General Chemistry, 4th Edition by Darrell D. Ebbing (Houghton Mifflin, 1993), the book that was in use at the time this test was written. The relevant values from the table in that book are as follows:

SUBSTANCEDHf
HCO3-(aq)-691.1 kJ/mol
Ca2+(aq)-543.0 kJ/mol
CaCO3(s)-1206.9 kJ/mol
CO2(g)-393.5 kJ/mol
H2O(l)-285.8 kJ/mol
The use of other thermochemical tables will give values close to the correct answer of -39.0 kJ, but there may be slight deviations due to small differences in various published sources of thermochemical data

6. What is the wavelength of light that has a frequency of 4.453 x 1014 / s?
a) 185.7 nmb) 255.8 nmc) 385.3 nmd) 491.7 nme) 673.2 nm
7. What is the energy of a photon of light that has a frequency of 5.139 x 1014 / s?

a) 1.289 x 10-48 Jb) 3.405 x 10-19 Jc) 1.401 x 10-18 Jd) 4.728 x 10-16 J
e) 2.115 x 10-15 J

8. If an electron in a hydrogen atom makes a transition from the n=6 state to the n=2 state, what is the wavelength of the emitted light?
a) 97.2 nmb) 102.5 nmc) 410.1 nmd) 486.0 nme) 656.1 nm
9. The l quantum number specifies

a) the energy of an electron in a hydrogen atom
b) the geometric shape of an orbital
c) which particular orbital within the sub-shell you are dealing with
d) the direction of the electron's spin

10. The ml quantum number specifies

a) the energy of an electron in a hydrogen atom
b) the geometric shape of an orbital
c) which particular orbital within the sub-shell you are dealing with
d) the direction of the electron's spin

11. The msquantum number specifies

a) the energy of an electron in a hydrogen atom
b) the geometric shape of an orbital
c) which particular orbital within the sub-shell you are dealing with
d) the direction of the electron's spin

12. The n quantum number specifies

a) the energy of an electron in a hydrogen atom
b) the geometric shape of an orbital
c) which particular orbital within the sub-shell you are dealing with
d) the direction of the electron's spin

13. All quantum numbers must have integer values EXCEPT:
a) nb) lc) mld) ms
14. Which quantum numbers can be assigned a value of 0 (zero)?
a) n onlyb) n and lc) n and msd) l and mle) ms only
15. Which quantum numbers can be equal to a negative integer?
a) n onlyb) l onlyc) ml onlyd) both n and mle) both l and ml
16. If n = 2, what is the maximum allowed value of l?
a) -2b) -1c) 0d) 1e) 2
17. If l = 3, what can be said about n?

a) n must be less than 3
b) n must be equal to 3
c) n must be greater than 3
d) n must be equal to 4
e) n must be greater than 4

18. Which of the following is a legal set of quantum numbers for an electron in an atom?

a) n = 2, l = 0, ml = 0, ms = 1
b) n = 1, l = 1, ml = 0, ms = 1/2
c) n = 4, l = 2, ml = -1 ms = 1/2
d) n = 4, l = 1, ml = -1/2 ms = 0
e) n = 0, l = 0, ml = 0, ms = -1/2

19. Which of the following is NOT a legal set of quantum numbers for an electron in an atom?

a) n = 5, l = 3, ml = 2, ms = 1/2
b) n = 3, l = 2, ml = 3, ms = -1/2
c) n = 4, l = 1, ml = 0, ms = 1/2
d) n = 1, l = 0, ml = 0, ms = -1/2
e) n = 6, l = 3, ml = -3, ms = 1/2

20. What is the value of the l quantum number for any s orbital?
a) 0b) 1c) 2d) 3e) 4
21. The letter designation for an orbital that has l = 1 is
a) Kb) Lc) sd) pe) d
22. What is the value of the n quantum number for any orbital in the M shell?
a) 0b) 1c) 2d) 3e) 4
23. What is the letter designation for the n = 1 shell?
a) Kb) sc) Nd) se) f
24. What is the maximum allowed value of the l quantum number for any orbital in the M shell?
a) 1b) 2c) 3d) 4e) 5
25. According to the Pauli Exclusion Principle:

a) Atoms generally require 8 electrons in order to fill their valence shell.

b) If a set of orbitals all have the same energy, then each orbital in the set must be occupied by one electron before any pairing of electrons will occur in those orbitals.

c) No two electrons in the same atom can have all four of their quantum numbers the same.

d) The total mass remains constant during a chemical reaction.

e) If a chemical reaction is the sum of two other chemical reactions, the DH of that reaction is the sum of the DH values of those two other chemical reactions.


ANSWERS:

1 d      2 d      3 a      4 e      5 c

6 e      7 b      8 c      9 b      10 c

11 d      12 a      13 d      14 d      15 c     

16 d      17 c      18 c      19 b      20 a     

21 d      22 d      23 a      24 b      25 c


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