Chemistry 112,
Exam 1 A
1. In each of the
following groups, pick the one that has the given property. Explain your answer.
(A)
Highest Melting Point: CH3CH2CH2CH2CH3 or (CH3CH2)2O
(B)
Highest Boiling Point: NO or N2
(C)
Smallest
Surface Tension: CH3CN or CH3OH
(D) Arrange the following substances in order of
increasing melting point.
Lowest → highest Cl2,
CsCl, CCl4, MgCl2,
2. Identify the intermolecular forces or bonding
in each of the compounds as a solid and explain what type of solid it would
form (molecular, metallic, ionic or network covalent).
|
Cpd |
IMF
or bond type |
Solid |
|
CO2 |
|
|
|
NaOH |
|
|
|
SiO2 |
|
|
|
U |
|
|
|
PH3 |
|
|
|
CCl4 |
|
|
3. Water has an enthalpy of vaporization of 40.7 kJ/mole. Calculate the boiling point of water in
4. Sketch a phase diagram of hydrazine and locate these points: triple point (2.0°C and 3.4 Torr), normal
melting point (1.4 °C)
normal boiling point (113.5 °C) critical point (380 °C and 145 atm). Show where
each phase exists.
5. Short answer:
Can a gas always be
liquefied by supplying enough pressure?
Why or why not?
Which has a higher Melting
Point CSe2 or SiO2?
Why?
What is capillary action?
Why can you hold your hand
in an oven at 100 °C for a few moments without much pain, but steam at 100 °C
will cause serious burns?
6. The osmotic pressure of a solution made by dissolving 0.8330 grams of a
protein in enough water to make 170.0 mL had an osmotic pressure of 10.40 Torr at a temperature of 25°C. What is the molar mass of the protein?
7. A 6.24 M solution of NaHCO3 (aq) has a density of 1.25
g/mL. What is the molality
of the solution?
8. How many liters of ethylene glycol C2H6O2
(d = 1.11g/mL) do you need to add to 8.5 kg. of water
in a car radiator to get a freezing point of −20.°C. Kf
(H2O) = 1.86 °C kg/mol.