CHM 151 Exam 3

Periodic trends/Bond Enthalpy

100

Which atom has the smallest radius?

Na, Cs, N, I

N

200

Which atom has the largest ionization energy?

Al, S, K, Sr

S

300

Arrange the following from weakest to strongest in terms of bond length:

SH, TeH, OH, SeH, PoH

OH<SH<SeH<TeH<PoH

400

Arrange the following from smallest to largest electron affinity:

F, Mg, Ba, Ag, Br

Ba, Mg, Ag, Br, F

500

Calculate the bond enthalpy of the following reaction:

Bond enthalpies: H−H: 432, O=O: 496, H−O: 463

H2(g) + 1⁄2 O2(g) ---> H2O(g)

 −246 kJ

Shapes/Polarity

100

What is the electron geometry of BF3?

Trigonal planar

200

What is the molecular geometry of NCl3?

Trigonal pyramidal

300

Draw and give the shape, angle, and if it is polar or not polar: CH2O

Trigonal planar, 120, polar

400

What is the formal charge of each atom in ICl4-?

I= -1, Cl= 0

500

Draw and give the shape, angle, and if it is polar or non polar: XeF4

Square planar, 90, non polar

Hybridization/Pi & Sigma bonds

100

What shape does each hybridization have?

sp= linear, sp2= trigonal planar, sp3= tetrahedral

200

What is the hybridization of CO2?

sp

300

How many sigma and pi bonds are there in C2H4?

5 sigma, 1 pi

400

What is the hybridization of each central atom in CH3CH2CH3?

sp3

500

How many sigma and pi bonds are there in...

34 sigma, 6 pi

Gas Laws

100

At what temperature will 0.654 moles of neon gas occupy 12.30 liters at 1.95 atm?

447 K

200

A 113L sample of helium at 27°C is cooled at constant pressure to -78.0°C. What is the new volume of the helium?

73 L

300

At 304 K, a 5.6 L container with H2 and N2 has a total pressure of 1.55 atm. If there are 0.034 moles of H2, what is the partial pressure of N2?

1.4 atm

400

A sample of argon gas at STP occupies 56.2 liters. What is the number of moles of argon and how many grams are in the sample?

2.51 mol, 100 g

500

96.0 g. of a gas occupies 48.0 L at 700.0 mm Hg and 20.0 °C. What is its molar mass?

52.2 g/mol

Intermolecular Forces

100

Arrange the intermolecular forces from weakest to strongest.

dispersion, dipole-dipole, hydrogen, ionic

200

Which of the following compounds is capable of hydrogen bonding?

CH3OCH3, CH3CH2OH, HF, CH3OH, CH3F, Br2

CH3CH2OH, HF, CH3OH

300

Which has the highest boiling point?

CH3CH2CH2OH, CH3CH2OCH3, (CH3)3N

CH3CH2CH2OH

400

Which of the following compounds is capable of dipole-dipole interactions?

CH4, SF6, CO2, NH4+, H2CO

H2CO

500

What intermolecular forces are present in the following molecules:

HCl, H2S, SiH4, CHCl3, NH3

HCl: dipole-dipole, H2S: dipole-dipole, SiH4: dispersion, CHCl3: dipole-dipole, NH3: hydrogen