CH 1010 Exam 2

Empirical Formula/Percent Composition Calculation

100

Caffeine has an elemental analysis of
49.48% C, 5.190% H, 16.47% O, and
28.85% N. It has a molar mass of 194.19
g/mol. What is the molecular formula of
caffeine?

C₈H₁₀N₄O

200

What is the percent composition of nitrogen in ammonium nitrate, NH₄NO₃?

35%

300

NaF is 29.8% by mass nitrogen. What mass of nitrogen is contained in 8.51 g of NaF?

2.46g

400

What is the empirical formula of a substance which is 54.52% carbon, 9.17% hydrogen, and 36.31% oxygen?

C₂H₄

500

A compound responsible for the odor of
garlic has a molecular weight of 146 g/mol.
A 0.650 g sample of the compound contains
0.321 g of carbon, 0.0449 g of hydrogen,
and 0.285 g of sulfur. What is the molecular
formula of the compound?

C₆H₁₀S₂

Electron Geometry

100

What is the electron geometry and molecular

shape of BCl3? What is the orbital hybridization

for the central atom?

Trigonal planar

Trigonal planar

sp²

200

How many of the following molecules have sp

hybridization on the central atom?

C₂Cl₂ CO₂ O₃ H₂O

C₂Cl₂  and CO₂

300

Place the following in order of increasing Se—X

bond angle, where X represents the outer atoms

in each molecule.

SeO₂ SeCl₆ SeF₂

SeCl₆ < SeF₂ < SeO₂ 

400

Consider the molecule propylene, C3H6. Its

structure has ___ sigma bonds and ___ pi bonds.

It has ___ single bonds, ___ double bonds and

___ triple bonds.

8 sigma bonds

1 pi bond

7 single

1 double

0 triple

500

How many of the following molecules contain at

least one pi bond?

C₂H₆ Cl₂CO C₂Cl₄ CS₂

Cl₂CO C₂Cl₄ CS₂

Lattice Energy

100

Lattice energy is directly related to what two things?

Charge and melting point

200

Which has the greater lattice energy cesium fluoride or calcium oxide?

Calcium oxide

300

Which has the greater lattice energy potassium bromide or rubidium iodide?

Potassium bromide

400

Arrange these compounds by decreasing melting point: 

strontium nitride, lithium nitride,

magnesium nitride and aluminum nitride.

aluminum nitride > magnesium nitride > strontium nitride > lithium nitride

500

Arrange the following by increasing lattice energy: 

NaF, Na₂O, MgO, BeO, MgF₂.

Naf < Na₂O < MgF₂ < MgO < BeO

Intermolecular Forces

100

Which is expected to have the largest dispersion

forces?

N₂ C₂H₆ CO₂ C₈H₁₈

C₈H₁₈

200

Which of the following compounds has the

highest boiling point?

HCl CH4 NH₃ H₂S

NH₃

300

Which of the following is likely to have the

highest viscosity at 25 degrees C?

C₄H₁₀ C₂H₅NH₂ C₂H₅SH C₈H₁₈

C₂H₅NH₂ 

400

Which of the following liquids has the highest

surface tension?

CH₃CH₂OH HOCH₂CH₂OH FCH₂CHF₂ CH₃CH₂F

CH₃OCH₃

HOCH₂CH₂OH

500

Choose the substance or substances that exhibits

dipole-dipole forces as its strongest

intermolecular force.

BCl₃ H₂ SO₂ CF₄ NH₃ CO₂

SO₂

Polyatomic Ions

100

ammonium

NH₄​⁺​​​

200

sulfate

SO₄^2-

300

permanganate

MnO₄^-

400

perchlorate

ClO₄^-

500

acetate

CH₃CO₂^-