Hour Exam One
CHEM 111
February 26, 2008
Do not write on the Exam; put all answers in the Blue Book.
Be sure to write your name on the cover of the Blue Book.
For partial and full credit show all work.
Total possible points = 100 points
1. Predict which of the following compounds would be the least soluble in water:
CH4, CH3NH2, CsBr, CH3OH.
Give the intermolecular (or interparticle) forces for each substance and explain your answer.
(12 pts)
2. Classify each of the solids: Li, CaCl2, C, Xe, BF3, as ionic, molecular, network,
metallic or atomic.
(10 pts)
3. Calculate the boiling point of an aqueous solution composed of 98.1 g of acetic acid,
CH3CO2H, in 125 mL of water.
(10 pts)
4. Draw the VSEPR structure of CH2O and give the bond angles and shape. Predict the polarity
(non-polar, polar) of the molecule.
(10 pts)
5. How many moles of magnesium carbonate are there in 50 g of an aqueous solution that is 12.8
wt % in the solute?
(10 pts)
6. The following set of data was obtained by the method of initial rates at 300 K for the reaction:
2 (H3C)3CH + O2  2 (H3C)3COH
(H3C)3CH(M)
0.25
0.50
0.50
O2 (M)
0.25
0.25
0.50
a) Give the Rate Law for the reaction.
b) Give the order of the reaction
c) Calculate the rate constant
Initial Rate (M s-1)
1.1 x 10-4
2.2 x 10-4
4.4 x 10-4
(12 pts)
7. The decomposition of acetaldehyde at 750 K is first order.
CH3CHO(g)  CH4(g) + CO(g)
a) What is the half life of the reaction if 0.80 mole of acetaldehyde in a 500 mL flask
decreases to 0.20 mole in 25.8 minutes?
b) .Calculate the rate constant for the decomposition.
(10 pts)
8. Choose the appropriate molecule:
a) Lowest vapor pressure at 0C: CH3CH2CH2CH2NH2, CH3CH2CH2CH2F,
CH3CH2CH2CH2CH3, CH3CH2OCH2CH3.
b) Lowest boiling point: SiH4, PH3, H2S, HCl
c) Highest melting point: CO2, Br2, Xe, C6H6.
d) Most polar molecule: H2, HCL, HF, CO
(16 pts)
9. The phase diagram of a substance is shown below.
a)
b)
c)
d)
Approximately, what is the normal melting point and normal boiling point?
Approximately, what is the pressure and temperature of the triple point?
What is the physical state of the substance at 360 K and 1.5 atm.?
What phase transition occurs if the substance at 0.50 atm is cooled from 150 K to 50 K ?
(10 pts)