Energy Change in Formation of Ionic Compounds

Bom - Haber Cycle Questions
Energy Change in the Formation of Ionic Compounds
1. In which pair do both compounds exhibit predominantly ionic bonding?
A) PClsandHF
B) Na2S03andBH3
C) KI and O 3
D) N a F a n d H 2 0
E) RbCl and CaO
2. When the cations Na^, K^, Rb^, Cs^ are combined with chloride ion in the gas phase to
form ion pairs, which pair formation releases the greatest amount of energy?
A) NaCl
B) KCl
C) RbCl
D) CsCl
E) All release the same amount of energy.
3. Which one of the following has an enthalpy change that is equal to the lattice energy of
SrBr2?
A) SrBr2(5) ^ Sr(^) + Br2(g)
B) SrBr2(5) ^ Sr(^) + Bnig)
C) SrBr2(5)^Sr2-(g) + 2Br(g)
D) SrBr2(5) -> Srfe) + 2Br(g)
E) SrBr2(5) -> Sf\s) + 2Br(g)
4. Which of the following statements concerning lattice energy is false?
A) Lattice energy is often defined as the energy released when an ionic solid forms
from its ions.
B) MgO has a larger lattice energy than NaF.
C) The lattice energy for a solid with 2+ and 2 - ions should be two times that for a
solid with 1+ and 1 - ions.
D) MgO has a larger lattice energy than LiF.
E) A l l of these are tme.
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5. In the Bom-Haber cycle for Nal(5), which of the following processes corresponds to the
first ionization energy of Na?
A) Na(g) ^ N a % ) + eB) N a % ) + l-(g)^NaI(5)
C) N a % ) + e - ^ N a ( g )
D) Na(5)^Na(g)
E) N a - ( g ) ^ N a ( g ) + e-
6. In the Bom-Haber cycle for RbCl(5), which of the following processes corresponds to
the enthalpy of formation of RbCl(5)?
A) Rb(g) + Cl2(g)^RbCl(g)
B) Rh(s) + 'AChig) RbCl(^)
C) RbCl(a^) ^ RbCl(5)
D) RbCl(g)-> RbCl(5)
E) Rb+(a^) + Cliaq)
RhC\(s)
7. In the Bom-Haber cycle for NaF(5), which of the following processes corresponds to the
electron affinity of F?
A) F ( g ) ^ F ^ ( g ) + eB) N a F ( 5 ) ^ N a % ) + F-(g)
C) F 2 ( g ) ^ 2 F ( g )
D) F-(g)->F(g) + eE) F(g) + e - ^ F - ( g )
8. Which of the following processes is not exothermic?
A) Rb^(g) + e - ^ R b ( g )
B) F(g) + e - ^ F - ( g )
C) R b % ) + F - ( g ) ^ R b F ( . )
D) Rb(g)^Rb(5)
E) '/2F2(g)->F(g)
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9. Calculate the lattice energy for LiF(s) given the following:
+166kJ/mol
sublimation energy for Li(s)
+77 kJ/mol
AHffoT ¥{g)
first ionization energy of Li(g)
electron affinity of F(g)
enthalpy of formation of LiF(5)
A)
B)
C)
D)
E)
10. The
A)
B)
C)
D)
E)
+520. kJ/mol
-328 kJ/mol
-617 kJ/mol
285 kJ/mol
-650. kJ/mol
800. kJ/mol
-1052kJ/mol
none of these
formation of which monatomic ion of sulfiir is the most energetically favorable?
SS^-
S^^
11. In the Bom-Haber Cycle describing energy change in formation of ionic compounds,
how many half reactions are exothermic and how many endothermic. Do not include
heat of formation energy change in this question.
A) 2 exothermic / 3 endothermic
B) 3 exothermic / 2 endothermic
C) 2 exothermic / 2 endothermic
D) 3 exothermic / 3 endothermic
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Chapter 8: Bonding in Ionic Compounds Worksheet #1
1,
Use a Bom-Haber Cycle to calculate the missing AH (bold reaction) of the following:
a.
Be(g)
- Be2*(g) + 2eBe(s)
Be(g)
1/2I2(S)
1(g)
1(g)+ er(g)
Be^"(g)+ 2r(g)
Bel2(s)
Be(s) + l2(s)
• Bel2(s)
AH = +2660 kJ/mole
AH = +302 kJ/mole
AH = +107 kJ/molel
AH
-295 kJ/mole
AH
AH - -208 kJ/mole Beh
b.
Mn(g)
*- Mn^+(g) + 2e"
Mn(s)
^ Mn(g)
S(s)
S(g)
S(g) + 2 e • S'-(g)
Mn^^(g) + S^"(g)
• MnS(s)
Mn(s) + S(s)
- MnS(s)
AH
AH
AH
AH
AH
AH
= +2230 kJ/mole
Li(g)
Li"(g) + eLi(s)
Li(g)
1/2 02(g)
- 0(g)
0(g) + 2 e- O'-(g)
2 Li^(g) + O'-(g)
" Li20(s)
2 L i ( s ) + l / 2 02(g)
^ Li20(s)
AH
AH
AH
AH
AH
AH
= +540 kJ/mole
+162 kJ/mole
c.
2.
= +264 kJ/mole
= +246 kJ/mole
-3176 kJ/mole
= -212 kJ/mole
= +598 kJ/mole
= -2800 kJ/mole Li20
= -554 kJ/mole U2O
Calculate the E A of F(g), in kJ/mole, given the following:
l E i + IE2 Sr(g) = +1580 kJ/mole
AHsubiimation Sr(s) = +144 kJ/mole
AHdissociation F2 = +79 kJ/molc F
AH/SrF2(s) = -1215 kJ/mole SrF2
AHiattice SrF2(s) = -2441 kJ/mole SrF2
EA F(g)