Test 3b practice
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Sara
Chem 177
Kingston
November 17, 2014
1) Label the following atoms as Ca, Mg, Ca2+
_Mg__
_Ca2+_ _____Ca_____
2) Polar covalent is__________.
a) Gaining electrons
b) Losing electrons
c) Transferring electrons
d) Equal sharing of electrons
e) Unequal sharing of electrons
Use the following table to answer the next 3
questions
3) Which letter element will have the largest first
ionization energy?
A
B
C
D
E
4) Which letter element will be the largest?
A
B
C
D
E
5) Which 2 letters will results in the highest difference in electronegative between them?A&B
A&C
D&A
D&C
B&D
6) Which of the following molecules has the shortest C-C bond?
a) C2H6
b) C2H4
c) C2H2
d) Benzene
7) Which of the following reacts the most vigorously with water?
a) K
b) Ca
c) Sr
d) Rb
e) Na
8) Place the following elements in order of increasing atomic radius: P, Ba, Cl
a) Ba < P < Cl
b) P < Cl < Ba
c) Cl < P < Ba
d) Cl < Ba < P
9) In which structure(s) below does the oxygen have a formal charge of +1?
a) I only
b) II only
c) I and III
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d) I and IV
e) I, III, and IV
10) Choose the bond below that is the strongest.
a) C-F
b) C=O
c) C-I
d) C≡N
11) Which bond is most polar?
a) C-N
b) C-O
c) N-O
d) F-O
e) F-C
12) Draw the 3 resonance structures for HPO42-. And add formal charges to all the atoms (the H
is attached to One of the O)
13) Using the average bond enthalpies below, estimate ∆H for the reaction.
2Br2(l) + C2H2  C2H4Br2
Bond:
Br-Br
C≡C
C-C
C-Br
C-H
Enthalpy 193
837
347
276
414
∆H°rxn = ∑ bond broken - ∑ bonds formed
∆H°rxn = [(2 mol)(Br-Br) + (2 mol)(C-H) + (1 mol)(C≡C)] – [(2 mol)(C-H) + (4 mol)(C-Br) + (1
mol)(C-C)]
∆H°rxn = [(2 mol)(193 kJ/mol) + (1 mol)(837 kJ/mol)] – [(4 mol)(276 kJ/mol) + (1mol)(347
kJ/mol)]
∆H°rxn = -228 kJ
14) If the dipole moment between 2 atoms that are 0.97 angstroms apart is 9.29D, what is the
charge in C? μ=Q*r
1A=1*10-10m
1D=3.34*10-30Cm
3.2*10^-19C
15) What is the Effective nuclear charge (Zeff) of Bromine?
Zeff=Z-(N0*0.35+N-1*0.85+N-2*1)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 Zeff=35-(6*0.35+18*0.85+10*1)
16) Draw the molecules:
i) PCl5
ii) BrF5iii) KrCl4
iv) SOBr2
b) Which molecule has the same electronic and molecular geometry? i
c) Which 2 molecules have the same electron geometry? ii and iii
d) What is the bond angle of iv? <109.5
e) Which are polar? ii and iv
17) Use VSEPR theory to predict the molecular geometry of BH3.
18) Which has the larger bond angle, ammonia (NH3) or ammonium (NH4+)?