Exam 5 (Chapter 10 and 11)
Another air purification method of enclosed spaces involves the use of scrubber containing aqueous lithium hydroxide, which reacts with carbon dioxide to produce lithium carbonate and water: 2LiOH (aq) + CO2 (g) ---> LiCO3(s) + H2O (l) Consider the air supply in a submarine with a total volume of 2.5 * 10^5 L. The pressure is 0.9970 atm, and the temperature at 25 degrees C. If the pressure in the submarine drops to 0.9891 atm as a result of carbon dioxide being consumed by aqueous lithium hydroxide scrubber, how many moles of CO2 are consumed
81
A sample of an unknown compound is vaporized at 200 degrees C. The gas produced has a volume of 780 mL at a pressure of 1.00 atm, and it weighs 1.91 g. Assuming the gas behaves ideally under these conditions, calculate molar mass (in g/mol)
95.0 g/mol
What is an instantaneous dipole?
A brief instance where an atom may have a slightly positive side and a slightly negative side due to the amount of electrons on that side
What is the root mean square speed?
*Square root* of the *mean* value of the *square* of the molecular speeds of the molecules of a gas.
CO2 is effective in fire extinguishers partly because its density is greater than that of air, so CO2 can smother the flames by depriving them of oxygen (air has a density of approximately 9.2 g/L at room temperature and 1 atm). Calculate density of CO2 at room temperature (25 degrees C) and 1.0 atm
1.8 g/L
Calculate to 3 significant figures the density of carbon dioxide at exactly 0 degrees C and exactly 1 atm. You can assume carbon dioxide gas behaves ideally
1.9634 g/L
If a child releases a 6.25 L helium balloon in the parking lot of an amusement park where the temperature is 28.50 degrees C and the air pressure is 757.2 mm Hg, what will the volume of the balloon be when it has risen to an altitude where the temperature is -34.35 degrees C and the air pressure is 366.4 mm Hg?
10.2 L
How pascals are in one atm?
101,325
How many pascals are in a bar?
10^5
How many pascals are in a torr?
133.322
How many pascals are in one mm Hg?
133.322
A sample of argon gas that originally occupied 14.6 L at 25.0 degrees C was heated to 50.0 degrees C at constant pressure. What is the new volume?
15.8 L
An arctic weather balloon is filled with 46.7 L of He gas inside a prep shed. The temperature inside the shed is 12 degrees C. The balloon is hone taken outside, where the temperature is -5 degrees C. Calculate new volume of balloon. You may assume the pressure of the balloon stays constant at exactly 1 atm
43.9 L
Based on the following information what is the molar mass of this gas? Volume=511.0 mL Mass=131.918 g Temperature=100 degrees C Mass of vapor in flask=0.768 g
46.0 g/mol
Ammonia gas and oxygen gas reaction to form water vapor and nitrogen monoxide gas. What volume of water should be produced by this reaction if 3.65 L of ammonia were consumed
5.48 L
A 1.00 L vessels contains 0.215 mol of N2 gas and 0.0118 mol of H2 gas at 25.5 degrees C. Determine the total pressure in the vessel
5.56 atm
A chemical engineer must calculate the maximum safe operating temperature of a high pressure gas reaction vessel. A stainless-steel cylinder that measure 26.0 cm wide and 31.2 cm high. The maximum safe pressure inside the vessel has been measured to be 3.40 MPa. For a certain reaction, the vessel may contain up to 1.13 kg of chlorine pentafluoride gas. Calculate maximum safe operating temperature the engineer should recommend
509 degrees C
A cylinder filled with 10.0 L of gas and a piston is put into it, the initial pressure of the gas is measured at 203 kPa. The piston is now pulled up, expanding the gas, until the gas has a final volume of 30.0 L. Calculate final pressure of the gas (in kPa)
67.7 kPa
What is the standard atmosphere pressure?
760 mm Hg and 0 degrees C (273.15 K)
A reaction at 22 degrees C evolves 363 mmol of sulfur hexafluoride gas. Calculate volume collected in L. You can assume pressure in the room is exactly 1 atm
8.79 L
What is the molar heat of evaporation (Delta H vap)?
Amount of heat required to vaporize a mole of substance at its boiling point
What is a barometer?
An instrument that measures atmospheric pressure
What is cohesion?
Attraction between molecules of the same substance
What is molar enthalpy of sublimation?
Energy usually expressed in kJ, required to sublime one mole of a solid
What is the molar mass of fusion?
Energy usually expressed in kJ/mol required to melt 1 mole of a solid
What causes a gas to not behave ideally?
High pressure and low temperature
What is volatile?
Higher vapor pressure at room temperature
What s a phase?
Homogenous part of a system that is separated from the rest of the system by a well defined boundary
How do you calculate the molar mass of a gas?
M=dRT/P
Does CF4 or CCl4 have the higher boiling point?
CCl4
What does kinetic molecular theory help explain?
The properties and behavior of gases
What is Boyle's Law?
The relationship between the pressure and volume of a gas. P varies inversely with V. P1V1 = P2V2.
What is dispersion force?
The result of fluctuations in the electron distribution within molecules or atoms. Present in ALL molecules and atoms.
What is boiling point?
The temperature at which a liquid boils
What is Dalton's Law?
The total pressure of a gas mixture is equal to the sum of the pressure that each gas would exert independently
What is Charle's law?
V1/T1 = V2/T2
What is Avogadro's Law?
V1/n1 = V2/n2
How do you find volume using the ideal gas law?
V=(R) nT/P
What is a phase change?
a transition of matter from one state to another
What is a supercritical fluid?
any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist
What is adhesion?
attraction between molecules of different substances
What is a dipole-dipole interaction?
attractive forces between polar molecules
How do you calculate the density of a gas?
d=PM/RT
What kind of intermolecular forces are in CH3COCH3(l)?
dispersion and dipole-dipole
What is freezing?
liquid to solid
What is diffusion?
mixing of gases
What is viscosity?
resistance to flow
What is sublimation?
solid to gas
What is melting/fusion?
solid to liquid
What is gas pressure?
the force exerted by a gas per unit surface area of an object
What is hydrogen bonding?
the intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom (N,O or F) is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule
what is Grahm's law of effusion?
under the same conditions, heavier gases travel slower
Calculate the mol fraction of NO in a 10.00 L gas cylinder at room temperature (25 degrees C) that contains 6.022 mol N2 in which total pressure is 14.75 atm
0.002
Calcium metal reacts with water to produce hydrogen gas Ca(s) + 2H2O (l) ---> Ca(OH)2 (aq) + H2(g) Determine the mass of H2 produced at 25 degrees C and 0.967 atm when 525 mL of gas is collected over water
0.0406 g
A reaction between liquid reactants takes place at -3.0 degrees C in a sealed, evacuated vessel with a measured volume of 25.0 L. Measurements show that the reaction produced 11 g of sulfur hexafluoride gas. Calculate pressure after the reaction.
0.067 atm
What is the value of R?
0.08206 L*atm/mol*K or 8.314 J/K*mol
Dinitrogen monoxide gas is collected at 9.0 degrees C in an evacuated flask with a measured volume of 50.0 L. When all the gas has been collected, the pressure in the flask is measured to be 0.200 atm. Calculate mass and number of moles
0.432 mol and 19.0 g
What is normal boiling point?
1 atm
What is the kinetic molecular theory of gases?
1. Particles in gas are separated by large distances 2. Molecules are in constant random motion, colliding with walls and with each other in perfectly elastic collisions 3. Molecules don't exert attractive or repulsive forces on each other 4. Average kinetic energy of gas molecules in a sample is proportional to the absolute temperature
The air bags in cars are inflated when a collision trigger the explosive, highly exothermic decomposition of sodium azide (NaN3) 2NaN3 (s) ---> 2Na(s) + 3N2(g) A typical driver-side air bag contains about 50 g of NaN. Determine the volume of N2 gas that would be generated by the decomposition of 50.0 g of sodium azide at 85.0 degrees C and 1.00 atm
33.9 L
What is the molar volume at STP
22.4 L
Calculate volume of a mole at room temperature (25 degrees C) and 1 atm
24.5 L
A cylinder filled with 10.0 L and a piston is put into it. The initial pressure of the gas is measured to be 240 kPa. the piston is now pushed down, compressing the gas, until the gas has a final volume of 8.70 L. Calculate the final pressure of the gas.
276 kPa
Sodium peroxide (Na2O2) is used to remove carbon dioxide from (and add oxygen to) the air supply in spacecrafts. It works by reacting with CO2 in the air to produce sodium carbonate (Na2CO3) and O2 2Na2O2(g) + 2CO2(g) ---> 2Na2CO3(g) + O2(g) What volume (in liters) of CO2 (at STP) will react with a kilogram of Na2O2
287 L
If we combine 3.0 L of NO and 1.5 L of O2 and they react according to the balanced equation: 2NO (g) + O2(g) ---> 2NO2(g) What volume of NO2 will be produced? (Assume the reactants and products are all of the same temperature and pressure)
3.0 L
If a skin diver takes a breath at the surface, filling his lungs with 5.82 L of air, what volume will the air in his lungs occupy when he dives to a depth where the pressure is 1.92 atm? (Assume constant temperature and that the pressure at the surface is exactly 1 atm
3.03 L
Determine how much faster a helium atom moves, on average, than carbon dioxide at the same temperature
3.3
What are the properties of a gas?
A gas has not fixed volume or shape. Rather, it assumes both the shape and the volume of the container it occupies.
What is effusion?
A process by which gas particles pass through a tiny opening
What is a pascal?
A unit of pressure equal to a force of 1 Newton acting over 1 square meter
Combustion of hydrocarbons such as methane (CH4) produce carbon dioxide, a green house gas. These gases in Earth's atmosphere can trap the sun's heat raising the average temperature of the Earth. For this reason there has been a great deal of international discussion about whether to regulate production of carbon dioxide. A) Write a balanced equation, including physical state symbols, for the combustion of gaseous methane into gaseous carbon dioxide and gaseous water B) Suppose 0.150 kg of methane are burned in air at a pressure of exactly 1 atm and a temperature of 17.0 degrees C. Calculate volume of carbon dioxide gas that is produced
A) CH4 (g) + 2O2(g) ---> CO2 (g) + 2H2O(g) B) 223 L
Ancient Romans often built out of bricks and mortar. A key ingredient was quicklime (calcium oxide), which they produced by roasting limestone (calcium carbonate). A) Write the balanced chemical equation for the decomposition of slid calcium carbonate (CaCO3) into solid calcium oxide and gaseous carbon dioxide. B) Suppose 33.0 L of carbon dioxide gas are produced by this reaction at a temperature of 350 degrees C and pressure of exactly 1 atm. Calculate mass of calcium carbonate that must have reacted
A) CaCO3(s) ---> CaO (s) + CO2(g) B) 64.6 g
What is critical temperature?
Gases liquefy if sufficient pressure is applied and the temperature is below a critical value called the critical temperature. A gas cannot be liquefied if the temperature is above the critical temperature.
A 6.00 L tank at 18.5 degrees C is filled with 3.48 g of dinitrogen monoxide gas and 3.74 g of boron trifluoride gas. You can assume both gases behave as ideal gases under these conditions. Calculate the mole fraction and partial pressure of each gas, and the total pressure in the tank
Dinitrogen monoxide mole fraction: 0.589 Dinitrogen monoxide partial pressure: 0.315 Boron trifluoride mole fraction: 0.411 Boron trifluoride partial presssure: 0.220 atm Total pressure: 0.535 atm
What kind of intermolecular forces are in CCl4 (l)?
Dispersion
What kind of intermolecular forces are in H2S(l)
Dispersion and dipole-dipole
What kind of intermolecular forces are in CH3COOH (l)?
Dispersion, dipole-dipole and hydrogen bonding
List the intermolecular forces from weakest to strongest.
Dispersion, dipole-dipole, hydrogen bonding, ion-dipole
Does GeI4 or GeBr4 have the higher boiling point?
GeI4
What is vapor pressure's relationship with temperature?
Increases with temperature
What is surface tension?
Measure of the elastic force in the surface of the liquid
What are the units for a pascal?
N/m^2 and kg/m*s^2
What is the SI unit for force?
Newton
What is Gay-Lussac's Law?
P1/T1 = P2/T2
What is the combined gas law?
P1V1/n1T1 = P2V2/n2T2
What is the ideal gas law?
PV=nRT
What is the SI unit for pressure?
Pascal
What are phase diagrams?
Phase diagrams show the relationships among temperature, composition, and phases present in a particular alloy system at equilibrium. Equilibrium means that the state of a system does not vary with time. Phase diagrams indicate the relationships among the structure, the composition, and the physical makeup of the alloy.
Does SiBr4 or SiI4 have the higher boiling point?
SiI4
What is the normal melting (or freezing) point of a substance?
Temperature at which it melts or freezes at 1 atm
What is the melting point of a solid or the freezing point of a liquid?
Temperature at which solid and liquid phases coexist
What is capillary action?
The ability of a liquid to flow against gravity up a narrow tube
What is critical pressure?
The minimum pressure required to convert a gas to a liquid at its critical temperature
What is vapor pressure?
a measure of the force exerted by a gas above a liquid
What is supercooling?
When a liquid is below it's freezing point without forming a solid
What are intermolecular forces?
forces of attraction between molecules
What is deposition?
gas to solid
What is compressibility of gases?
high
What is a manometer?
instrument used to measure gas pressure in a closed container
What is an Ion-dipole interaction?
interactions between a polar molecule and an ion