Final Exam CHEM 219
_________ is a measure of the tendency of a material to change into the gaseous state - Correct Answer Vapor
pressure is a measure of the tendency of a material to change into the gaseous state. The molecules are moving
rapidly and if they have enough energy they will escape from the liquid.
(NH₄)₂SO₄ has a van't Hoff factor of i = 2.3. What is the concentration of particles in a 0.7801 M solution of
(NH₄)₂SO₄? - Correct Answer 1.8 M
2.3 x 0.7801 = 1.8
M=(i)x(M)
A bond in which an electron pair is unequally shared by two atoms is
A) ionic.
B) polar covalent.
C) nonpolar covalent.
D) coordinate covalent.
E) dipolar. - Correct Answer B) polar covalent.
A solution is made by dissolving 2.5 mg sodium fluoride (NaF) in 1.5 L of water at 20.0°C. What is the fluoride ion
concentration in ppm of the resulting solution, given that NaF is 45.0% fluoride ion by mass, and the density of water
of 1.00 kg/L? - Correct Answer 2.5 x 45/100 = 1.125mg
weight of ion / weight of water = ppm
so, 1.5L = 1.5 Kg
1.125mg / 1.5 kg = 0.75
A solution is made using 163.7 g of dimethyl ether (MM = 46.07 g/mol) and 90.0 g of methanol (MM = 32.04 g/mol).
What is the mole fraction of the dimethyl ether in the solution? - Correct Answer find mol of dim & methanol
dim mol / dim mol + methanol = mol fraction
A solution is made using 175.7 g of hexane (MM = 86.18 g/mol) and 200.0 g of octane (MM = 114.2 g/mol). What is
the molality of the hexane in the solution? - Correct Answer m = (W g of solute / Molar mass of solute) (1000 / W g of
solvent)
(175.7g / 86.18g/mol) ( g) = 10.19m
A theory is another word for a(n) _________. - Correct Answer A theory or model is a well established explanation of
a phenomenon based on a series of facts and a body of evidence.
All the following statements concerning a sample of oxygen gas at 1.00 atm pressure are true EXCEPT
A) the molecules are in constant rapid random motion.
B) the pressure exerted by gaseous oxygen is due to the impact of the molecules with the walls of the container.
C) the average kinetic energy of the gaseous oxygen is inversely proportional to the absolute temperature of the gas.
D) collisions between the gaseous molecules are elastic.
E) the volume occupied by the oxygen molecules is negligible compared with the size of the container. - Correct
Answer C) the average kinetic energy of the gaseous oxygen is inversely proportional to the absolute temperature of
the gas.
All will contribute equally. Because boiling point elevation is a colligative property, it depends only on the
concentration of solute, not the type of solute. - Correct Answer Vapor pressure describes the tendency of a
substance to change from the liquid to the gas phase, so substances with weaker intermolecular forces will have
higher vapor pressures. A substance's boiling point is also indicative of the strength of the intermolecular forces, with
weaker intermolecular forces resulting in lower boiling points. Because acetone has the lowest boiling point of the
options given, it has the weakest intermolecular forces, and will therefore have the highest vapor pressure.
, Amonton's Law - Correct Answer if the volume of a gas is held constant, increasing the temperature of the gas
increases its pressure.
An exothermic reaction causes the surroundings to - Correct Answer An exothermic reaction transfers energy from
the system to the surroundings. That tells us the surroundings will get warmer.
At a particular temperature, the solubility of H₂ in water is 0.140 M when the partial pressure is 1.20 atm. What partial
pressure (in atm) of H₂ would give a solubility of 4.95 M? - Correct Answer 42.4 atm
C = kP --> c12/c1 = p2/p1
Avagadro's Law
in terms of KE - Correct Answer Container pressure constant, more gas molecules added = increased volume
Avogadro's Law - Correct Answer equal volumes of gases at the same temperature and pressure contain equal
numbers of molecules
Boyle's Law
in terms of KE - Correct Answer Volume decreased, wall area decreased = increased pressure
Boyle's Law - Correct Answer Boyle's Law states that at constant temperature and moles, pressure and volume are
inversely proportional.
Mathematically this is written as: PV = PV
CaCl₂ is often used to melt ice on sidewalks. Calcium chloride is more effective at melting ice than NaCl. Choose the
best explanation for this observation. - Correct Answer CaCl₂ dissociates into three ions increasing the concentration
of solute species in solution. The ions have strong intermolecular interactions with water molecules and, thus,
decrease the ability of the water molecules to pack tightly with each other. The more ions present, the harder it is to
crystallize water into ice.
Charles' Law - Correct Answer the law that states that for a fixed amount of gas at a constant pressure, the volume of
the gas increases as the temperature of the gas increases and the volume of the gas decreases as the temperature
of the gas decreases
Clausius-Clapeyron Equation - Correct Answer The equation below can be used with just two measurements of vapor
pressure and temperature
Combined Gas Law - Correct Answer the relationship between the pressure, volume, and temperature of a fixed
amount of gas
Dalton's Law - Correct Answer The total pressure of a mixture of gases is the sum of the individual pressures
(Ptotal=P1+P2+P3...)
Density equation - Correct Answer mass/volume
dRT = PM
diffusion - Correct Answer Diffusion is the movement of a substance from an area of high concentration to an area of
lower concentration. In this picture, the purple substance moves from a concentrated area to become dispersed
throughout the aqueous solution.
Dispersion forces are due to - Correct Answer temporary dipoles
For a molecule to exhibit dipole-dipole interactions, it must - Correct Answer have a permanent dipole moment
Forming solution A from liquid B and liquid C is endothermic. Increasing the pressure above the solution will - Correct
Answer Since the solution does not contain any gases, and since liquids are incompressible, then a change in
pressure will have no effect on the solution process.
Gay-Lussac's Law - Correct Answer the pressure of a gas is directly proportional to the Kelvin temperature if the
volume is constant
_________ is a measure of the tendency of a material to change into the gaseous state - Correct Answer Vapor
pressure is a measure of the tendency of a material to change into the gaseous state. The molecules are moving
rapidly and if they have enough energy they will escape from the liquid.
(NH₄)₂SO₄ has a van't Hoff factor of i = 2.3. What is the concentration of particles in a 0.7801 M solution of
(NH₄)₂SO₄? - Correct Answer 1.8 M
2.3 x 0.7801 = 1.8
M=(i)x(M)
A bond in which an electron pair is unequally shared by two atoms is
A) ionic.
B) polar covalent.
C) nonpolar covalent.
D) coordinate covalent.
E) dipolar. - Correct Answer B) polar covalent.
A solution is made by dissolving 2.5 mg sodium fluoride (NaF) in 1.5 L of water at 20.0°C. What is the fluoride ion
concentration in ppm of the resulting solution, given that NaF is 45.0% fluoride ion by mass, and the density of water
of 1.00 kg/L? - Correct Answer 2.5 x 45/100 = 1.125mg
weight of ion / weight of water = ppm
so, 1.5L = 1.5 Kg
1.125mg / 1.5 kg = 0.75
A solution is made using 163.7 g of dimethyl ether (MM = 46.07 g/mol) and 90.0 g of methanol (MM = 32.04 g/mol).
What is the mole fraction of the dimethyl ether in the solution? - Correct Answer find mol of dim & methanol
dim mol / dim mol + methanol = mol fraction
A solution is made using 175.7 g of hexane (MM = 86.18 g/mol) and 200.0 g of octane (MM = 114.2 g/mol). What is
the molality of the hexane in the solution? - Correct Answer m = (W g of solute / Molar mass of solute) (1000 / W g of
solvent)
(175.7g / 86.18g/mol) ( g) = 10.19m
A theory is another word for a(n) _________. - Correct Answer A theory or model is a well established explanation of
a phenomenon based on a series of facts and a body of evidence.
All the following statements concerning a sample of oxygen gas at 1.00 atm pressure are true EXCEPT
A) the molecules are in constant rapid random motion.
B) the pressure exerted by gaseous oxygen is due to the impact of the molecules with the walls of the container.
C) the average kinetic energy of the gaseous oxygen is inversely proportional to the absolute temperature of the gas.
D) collisions between the gaseous molecules are elastic.
E) the volume occupied by the oxygen molecules is negligible compared with the size of the container. - Correct
Answer C) the average kinetic energy of the gaseous oxygen is inversely proportional to the absolute temperature of
the gas.
All will contribute equally. Because boiling point elevation is a colligative property, it depends only on the
concentration of solute, not the type of solute. - Correct Answer Vapor pressure describes the tendency of a
substance to change from the liquid to the gas phase, so substances with weaker intermolecular forces will have
higher vapor pressures. A substance's boiling point is also indicative of the strength of the intermolecular forces, with
weaker intermolecular forces resulting in lower boiling points. Because acetone has the lowest boiling point of the
options given, it has the weakest intermolecular forces, and will therefore have the highest vapor pressure.
, Amonton's Law - Correct Answer if the volume of a gas is held constant, increasing the temperature of the gas
increases its pressure.
An exothermic reaction causes the surroundings to - Correct Answer An exothermic reaction transfers energy from
the system to the surroundings. That tells us the surroundings will get warmer.
At a particular temperature, the solubility of H₂ in water is 0.140 M when the partial pressure is 1.20 atm. What partial
pressure (in atm) of H₂ would give a solubility of 4.95 M? - Correct Answer 42.4 atm
C = kP --> c12/c1 = p2/p1
Avagadro's Law
in terms of KE - Correct Answer Container pressure constant, more gas molecules added = increased volume
Avogadro's Law - Correct Answer equal volumes of gases at the same temperature and pressure contain equal
numbers of molecules
Boyle's Law
in terms of KE - Correct Answer Volume decreased, wall area decreased = increased pressure
Boyle's Law - Correct Answer Boyle's Law states that at constant temperature and moles, pressure and volume are
inversely proportional.
Mathematically this is written as: PV = PV
CaCl₂ is often used to melt ice on sidewalks. Calcium chloride is more effective at melting ice than NaCl. Choose the
best explanation for this observation. - Correct Answer CaCl₂ dissociates into three ions increasing the concentration
of solute species in solution. The ions have strong intermolecular interactions with water molecules and, thus,
decrease the ability of the water molecules to pack tightly with each other. The more ions present, the harder it is to
crystallize water into ice.
Charles' Law - Correct Answer the law that states that for a fixed amount of gas at a constant pressure, the volume of
the gas increases as the temperature of the gas increases and the volume of the gas decreases as the temperature
of the gas decreases
Clausius-Clapeyron Equation - Correct Answer The equation below can be used with just two measurements of vapor
pressure and temperature
Combined Gas Law - Correct Answer the relationship between the pressure, volume, and temperature of a fixed
amount of gas
Dalton's Law - Correct Answer The total pressure of a mixture of gases is the sum of the individual pressures
(Ptotal=P1+P2+P3...)
Density equation - Correct Answer mass/volume
dRT = PM
diffusion - Correct Answer Diffusion is the movement of a substance from an area of high concentration to an area of
lower concentration. In this picture, the purple substance moves from a concentrated area to become dispersed
throughout the aqueous solution.
Dispersion forces are due to - Correct Answer temporary dipoles
For a molecule to exhibit dipole-dipole interactions, it must - Correct Answer have a permanent dipole moment
Forming solution A from liquid B and liquid C is endothermic. Increasing the pressure above the solution will - Correct
Answer Since the solution does not contain any gases, and since liquids are incompressible, then a change in
pressure will have no effect on the solution process.
Gay-Lussac's Law - Correct Answer the pressure of a gas is directly proportional to the Kelvin temperature if the
volume is constant
