Ideal Gas Law
Gas
Enthalpy
Fun! *insert evil laugh*
IMF
100
A sample container of CO occupies a volume of 440 mL at a pressure of 1452 mm Hg and a temperature of 345 K. What would the temperature be if the volume changed to 5.34 L and the pressure changed to 3 atm?
T2= 6.58 x 10³ K
100
A mixture of gasses at 760.0 torr contain 25% nitrogen, 46% oxygen, and 29% carbon dioxide by volume. What is the pressure of the carbon dioxide gas in torr?
220.4 torr
100
If the internal energy of a thermodynamic system is increased by 300 J while 75 J of expansion work is done on it, how much heat was transferred and in which direction, to or from the system?
375 J heat transferred to the system
100
List the number of atoms present in each unit cell: simple cubic, body-centered cubic, and face-centered cubic.
SC = 1, BCC = 2, FCC = 4
100
List all the intermolecular forces and describe them.
London-Dispersion: temporary dipoles due to the nature of electrons
Dipole-Dipole: permanent dipoles due to electronegativity
Hydrogen bond: strong dipole-dipole, H-N, O, or F
200
The mass of 560 cm³ of an unknown gas is 1.60g at STP. Which of the following gasses is it: O₂, Cl₂, CO₂, SO₂?
SO₂
200
A 2.5 atm sample of N₂ effuses through a small opening in 2.0 min. If a sample of an unknown gas under the same conditions takes 4.2 min to diffuse, what is its molar mass?
107 g/mol
200
One of the components of polluted air is NO. It is formed in the high-temperature environment of internal combustion engines by a reaction with ΔH= 180 kJ. Why are high temperatures needed to convert N₂ and O₂ to NO?
The process is an endothermic reaction, as shown by the positive value of enthalpy change.
200
A sample of nickel is heated to 99.88 C and placed in a coffee-cup calorimeter containing 150.0 g water at 23.58 C. After the metal cools, the final temperature of the metal and water mixture is 25.08 C. If the specific heat capacity of nickel is 0.444 J/C*g, what mass of nickel was originally heated? Assume no heat loss to the surroundings.
28 g Ni
200
Draw a phase-change diagram including all labels.
300
Draw a graphical representation of Boyle’s Law.
300
If you have two gasses that are at the same temperature, pressure, and volume in two separate containers, what is true about the moles of gas in each container? Support your answer.
Moles are the same (Use PV=nRT to justify)
300
A coffee-cup calorimeter initially contains 125 g of water at 24.28 C. Potassium bromide (10.5 g), also at 24.28 C, is added to the water, and after the KBr dissolves, the final temperature is 21.18 C. Calculate the enthalpy change for dissolving the salt in J/g. Assume that the specific heat capacity of the solution is 4.18 J/C*g and that no heat is transferred to the surroundings or to the calorimeter.
170 J/g
300
A certain flexible weather balloon contains helium gas at a volume of 855 L. Initially, the balloon is at sea level where the temperature is 258 C and the barometric pressure is 730 torr. The balloon then rises to an altitude of 6000 ft, where the pressure is 605 torr and the temperature is 158C. What is the change in volume of the balloon as it ascends from sea level to 6000 ft?
631.8 L
300
Calcium has a cubic closest packed (face-centered) structure as a solid. Assuming that calcium has an atomic radius of 197 pm, calculate the density of solid calcium.
1.54 g/cm³
400
A particular balloon is designed by its manufacturer to be inflated to a volume of no more than 2.5 L. If the balloon is filled with 2.0 L helium at sea level (1 atm), and rises to an altitude at which the atmospheric pressure is only 500 mmHg,will the balloon burst? (Assume temperature is constant.)
Yes, the balloon will burst. Volume will be approximately 3 L
400
If a barometer were built using water (d=1.0 g/cm³) instead of mercury (d=13.6 g/cm³), would the column of water be higher than, lower than, or the same as the column of mercury at 1.00 atm? If the level is different, by what factor? Explain.
Higher than! If the pressure is held constant, the volume of water must increase to match the same pressure since it has a lower density.
400
Describe the difference between an endothermic and exothermic reaction, define the term state function with a chemical example, and write an equation used to calculate enthalpy or energy of a reaction.
Exothermic: Energy in the form of heat is released to the surroundings from the system, ΔH= -
Endothermic: Energy in the form of heat is absorbed from the surroundings to the system, ΔH= +
State function: property of a system that does not depend on the path taken to achieve the final state, only the initial and final states (ex: enthalpy)
q=MCΔT, ΔE= q + w
400
Freon‑12 (CF2Cl2) is commonly used as the refrigerant in central home air conditioners. The system is initially charged to a pressure of 4.8 atm. Express this pressure in each of the following units: mmHg, torr, Pa.
3.6 x 10³ mmHg , 3.6 x 10³ torr , 4.9 x 10⁵ Pa
400
You have three covalent compounds with three very different boiling points. All of the compounds have similar molar mass and relative shape. Explain how these three compounds could have very different boiling points.
All compounds have different intermolecular forces.
500
A chemist weighed out 5.14 g of a mixture containing unknown amounts of BaO(s) and CaO(s) and placed the sample in a 1.50‑L flask containing CO₂(g) at 30.08 C and 750. torr. After the reaction to form BaCO₃(s) and CaCO₃(s) was completed,the pressure of CO₂(g) remaining was 230 torr. Calculate the mass percentages of CaO(s) and BaO(s) in the mixture.
13.4% CaO, 86.6% BaO
500
A compound contains only C, H, and N. It is 58.51% C and 7.37% H by mass. Helium effuses through a porous frit 3.20 times as fast as the compound does. Determine the empirical and molecular formulas of this compound.
C₂H₃N for both
500
The enthalpy of combustion of solid carbon to form carbon dioxide is 2393.7 kJ/mol carbon, and the enthalpy of combustion of carbon monoxide to form carbon dioxide is 2283.3 kJ/mol CO. Use these data to calculate ΔH for the reaction written on the board.
-220.8 kJ
500
It has been determined that the body can generate 5500 kJ of energy during one hour of strenuous exercise. Perspiration is the body’s mechanism for eliminating this heat. What mass of water would have to be evaporated through perspiration to rid the body of the heat generated during 2 hours of exercise? (The heat of vaporization of water is 40.6 kJ/mol.)
4880.9 g H₂O
500
Mn crystallizes in the same type of cubic unit cell as Cu. Assuming that the radius of Mn is 5.6% larger than the radius of Cu and the density of copper is 8.96 g/cm³, calculate the density of Mn.
6.58 g/cm³