Chemistry practice skills Essay
Chemistry practice skills
What type of forces must be overcome when solid I2 dissolves in methanol, CH3OH?
Induced dipole What type of forces must be disrupted between CH3OH molecules when I2 dissolves? Hydrogen bonding
What type of forces exist between I2 and CH3OH molecules in solution?
4) What type of intermolecular forces must be overcome in converting each of the following from a liquid to a gas?
a) CO2 London forces, dipole-dipole
b) NH3 London forces, dipole-dipole, hydrogen
c) CHCl3 London forces, dipole-dipole
d) CCl4 London forces
6) Rank the following in order of increasing strength of intermolecular forces in the pure substances. Which substance exists as a gas at 25 ®C and 1 atm?
He < CH3OH < CH3CH2CH2CH3
He (helium) and CH3CH2CH2CH3 (butane) exist as a gas at 25® C and 1 atm
12) The enthalpy of vaporization of liquid mercury is 59.11kJ/mol. What quantity of energy as heat is required to vaporize 0.500 mL of mercury at 357®C, its normal boiling point? The density of mercury is 13.6 g/mL.
16) Figure 12.17
a) if water is placed in a sealed milk carton at 60 degrees Celsius and sealed tightly and allowed to cool, eventually there will be an equilibrium of liquid and vapor. Gas is not able to escape and masses of the liquid and
vapor remain constant.
b) assuming that the temperature your hand is below 34.6 degrees Celsius, liquid diethyl ether should remain a liquid if dropped on your hand.
22) Vapor pressure data for octane C8H18
38.6 kJ/mol, normal boiling point 128® C
26) What factors affect the viscosity of a substance?
Temperature, size of the molecule, polarity, and the amount of substance present affect viscosity. Which of the following substances is expected to have the highest viscosity? Glycerol has the highest viscosity because it has the greatest amount of intermolecular forces.
Should viscosity of a substance be affected by temperature? Explain. As the temperature of a liquid increases the kinetic energy required to separate the intermolecular forces also increases. The amount of separation that occurs is a measure of the viscosity, the opposite effect occurs when a liquid is cooled as the energy level is minimal.