chm 113 exam 4

CHM113 summer 2014 Name: __________________________
EXAM 4

SHOW YOUR WORK

1) Of the molecules below, the bond in __________ is the least polar.
A) HBr
B) HI
C) HCl
D) HF
E) H2

2) Ethanol (C2H5OH) melts at -114°C. The enthalpy of fusion is 5.02 kJ/mol. The heat capacity of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135°C to liquid ethanol at -50°C?

A) 207.3
B) -12.7
C) 6.91
D) 4192
E) 9.21

3) Which equation correctly represents the first ionization of aluminum?
A) Al- (g) → Al (g) + e-
B) Al (g) → Al- (g) + e-
C) Al (g) + e- → Al- (g)
D) Al (g) → Al+ (g) + e-
E) Al+ (g) + e- → Al (g)

4) The molecular geometry of the OH2 molecule is __________.
A) linear
B) bent
C) trigonal planar
D) tetrahedral
E) octahedral

5) Which of the following correctly represents the second ionization of calcium?
A) Ca (g) → Ca+ (g) + e-
B) Ca+ (g) → Ca2+ (g) + e-
C) Ca- (g) + e- → Ca2- (g)
D) Ca+ (g) + e- → Ca2+ (g)
E) Ca+ (g) + e- → Ca (g)

6) Using the VSEPR model, the molecular geometry of the central atom in CF4 is __________.
A) linear
B) trigonal planar
C) tetrahedral
D) bent
E) trigonal pyramidal

7) In which of the molecules below is the carbon-carbon distance the shortest?
A) H2C=CH2
B) H–C≡ C–H
C) H3C–CH3
D) H3C–CH2–C H3

8) The Cl-Si-Cl bond angle in the SiCl2F2 molecule is approximately __________.
A) linear
B) trigonal planar
C) tetrahedral
D) bent
E) trigonal pyramidal

9) Given the electronegativities below, which covalent single bond is most polar?
Element: H C N O
Electronegativity: 2.1 2.5 3.0 3.5

A) C–H
B) N–H
C) O–H
D) O–C
E) O–N

10) Using the table of bond dissociation energies, the ΔH for the following gas-phase reaction is __________ kJ.

A) -44
B) 38
C) 304
D) 2134
E) -38

11) The mole fraction of urea (MW = 60.0 g/mol) in a