Q&A Hero

Q: Assume that you have a sample of gas in a cylinder with a moveable piston, as shown in diagram (1). The initial pressure, number of moles, and temperature of the gas are noted on the diagram. Which diagram (2)-(4) most closely represents the result of doubling the number of moles of gas while keeping the pressure and temperature constant? A) diagram (2) B) diagram (3) C) diagram (4)

Q: Which drawing best shows the approximate level of the mercury in the tube when a vacuum pump is connected to the top of the tube, the stopcock opened, the tube is evacuated, the stopcock is closed, and the pump is removed, and the stopcock is reopened? A) drawing (1) B) drawing (2) C) drawing (3) D) drawing (4)

Q: Which drawing best shows the approximate level of the mercury in the tube when a vacuum pump is connected to the top of the tube, the stopcock opened, the tube is evacuated, the stopcock is closed, and the pump is removed? A) drawing (1) B) drawing (2) C) drawing (3) D) drawing (4)

Q: Which drawing best shows the approximate level of the mercury in the tube when the temperature of the entire apparatus is lowered from +20C to -20C? A) drawing (1) B) drawing (2) C) drawing (3) D) drawing (4)

Q: When stopcock A of the open-end manometer shown below is opened, which drawing best represents the result? A) drawing (1) B) drawing (2) C) drawing (3) D) drawing (4)

Q: What is the pressure (in mm Hg) of the gas inside the above apparatus if the outside pressure, Patm, is 750 mm Hg and the difference in mercury levels, h, is 25 mm Hg?A) 25 mm HgB) 725 mm HgC) 750 mm HgD) 775 mm Hg

Q: What is the pressure (in mm Hg) of the gas inside the above apparatus if the outside pressure, Patm, is 745 mm Hg and the difference in mercury levels, h, is 25 mm Hg?A) 25 mm HgB) 720 mm HgC) 745 mm HgD) 770 mm Hg

Q: What is the pressure (in mm Hg) of the gas inside the above apparatus if the outside pressure, Patm, is 745 mm Hg and the difference in mercury levels, h, is 25 mm Hg?A) 25 mm HgB) 720 mm HgC) 745 mm HgD) 770 mm Hg

Q: What is the pressure (in mm Hg) of the gas inside the above apparatus if the outside pressure, Patm, is 736 mm Hg and the difference in mercury levels, h, is 18 mm Hg?A) 18 mm HgB) 718 mm HgC) 736 mm HgD) 754 mm Hg

Q: What is the pressure (in mm Hg) of the gas inside the above apparatus if the outside pressure, Patm, is 750 mm Hg and the difference in mercury levels, h, is 50 mm Hg?A) 50 mm HgB) 700 mm HgC) 750 mm HgD) 800 mm Hg

Q: What is the pressure (in mm Hg) of the gas inside the above apparatus if the outside pressure, Patm, is 740 mm Hg and the difference in mercury levels, h, is 30 mm Hg?A) 30 mm HgB) 710 mm HgC) 740 mm HgD) 770 mm Hg

Q: An unusual correlation exists between the potency of an inhaled anesthetic and its ability to A) dissolve in olive oil. B) effuse through a porous membrane. C) expand and compress. D) react with ozone.

Q: The major source of Cl atoms in the stratosphere is from A) CFC's. B) NaCl. C) Cl2. D) HCl.

Q: The principal cause of man-made ozone depletion in the stratosphere is due to A) NO2. B) CH4. C) CO2. D) Cl.

Q: Which of the following substances has increased markedly due to the use of fossil fuels and contributes to the greenhouse effect? A) CO2 B) SO2 C) NO2 D) O3

Q: Which of the following is the principal cause of global warming? A) acid rain B) air pollution C) greenhouse effect D) ozone depletion

Q: One reaction that contributes to photochemical smog is shown below. Which of the species involved contains one or more unpaired electrons?NO2(g) + hÏ… -> NO(g) + O(g)A) only NO2(g)B) only NO2(g) and NO(g)C) only O(g)D) All of the these contain unpaired electrons.

Q: Which of the following regions of the earth's atmosphere contains the ozone layer? A) mesosphere B) stratosphere C) thermosphere D) troposphere

Q: Which of the following regions of the earth's atmosphere is closest to the surface of the earth? A) mesosphere B) stratosphere C) thermosphere D) troposphere

Q: The lowest atmospheric temperatures are found at the A) earths surface. B) troposphere/stratosphere junction. C) stratosphere/mesosphere junction. D) mesosphere/thermosphere junction.

Q: Which of the following regions of the earth's atmosphere is farthest from the surface of the earth? A) mesosphere B) stratosphere C) thermosphere D) troposphere

Q: Which statement about real gases is true? A) The volume of the gas particles is zero. B) The mass of the gas particles is zero. C) Forces of attraction and repulsion exist between gas particles at close range. D) The behavior of real gases can be exactly predicted using the ideal gas law.

Q: Which of the noble gases should show the greatest deviation from the ideal gas law at high pressures? A) He B) Ar C) Rn D) All deviate equally.

Q: An unknown gas contains 83% C and 17% H by mass. If effuses at 0.87 times the rate of CO2 gas under the same conditions. What is the molecular formula of the unknown gas? A) C2H5 B) C3H3 C) C4H10 D) C7H17

Q: If CO2 and NH3 are allowed to effuse through a porous membrane under identical conditions, the rate of effusion for NH3 will be ________ times that of CO2. A) 0.39 B) 0.62 C) 1.6 D) 2.6

Q: An unknown gas effuses 2.3 times faster than N2O4 at the same temperature. What is the identity of the unknown gas? A) CN2 B) NH3 C) N2O D) O3

Q: An unknown gas effuses 1.73 times faster than krypton. What is the molar mass of the gas? A) 28.0 g/mol B) 48.4 g/mol C) 110 g/mol D) 251 g/mol

Q: Which one of the following gases will have the lowest rate of effusion? A) SF4 B) SCl4 C) S2O5 D) SO3

Q: Which one of the following gases will have the highest rate of effusion? A) NO2 B) N2O C) N2O4 D) NO3

Q: A process by which gas molecules escape through a tiny hole in a membrane into a vacuum without collisions is called A) Boyle's law. B) diffusion. C) effusion. D) sublimation.

Q: The mixing of different gases by random molecular motion with frequent collisions is called A) Avogadro's law. B) compressibility. C) diffusion. D) effusion.

Q: Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory, which gas has the highest average kinetic energy? A) Ar B) Cl2 C) N2 D) All have identical average kinetic energies

Q: Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory, which gas has the highest density? A) Ar B) Cl2 C) N2 D) All have identical densities

Q: Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory, which gas has the highest pressure? A) Ar B) Cl2 C) N2 D) All have identical pressures

Q: Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory, which gas has the highest average speed? A) Ar B) Cl2 C) N2 D) All have identical average speeds

Q: Each of three identical 15.0-L gas cylinders contains 7.50 mol of gas at 295 K. Cylinder A contains Ar, cylinder B contains Cl2, and cylinder C contains N2. According to the kinetic molecular theory, which gas has the highest collision frequency? A) Ar B) Cl2 C) N2 D) All have identical collision frequencies

Q: You are given two flasks of equal volume. One contains H2 at 0C and 1 atm while the other contains CO2 at 0C and 2 atm. Which of the following quantities will be the same for both flasks? A) average molecular kinetic energy B) average molecular speed C) density D) number of molecules present

Q: At what temperature will sulfur hexafluoride molecules have the same average speed as argon atoms at 20C? A) -22.0C B) 73.2C C) 381C D) 799C

Q: What is the temperature of CO2 gas if the average speed (actually the root-mean-square speed) of the molecules is 750 m/s? A) 1.32 K B) 9.92 102 K C) 1.31 103 K D) 9.92 105 K

Q: Which of the following gases has the lowest average speed at 25C? A) CH4 B) H2S C) NH3 D) O2

Q: Which of the following gases has the highest average speed at 400K? A) CO2 B) N2O4 C) SF6 D) UF6

Q: What is the average speed (actually the root-mean-square speed) of a neon atom at 27C? A) 5.78 m/s B) 19.3 m/s C) 183 m/s D) 609 m/s

Q: According to the kinetic molecular theory, the pressure of a gas in a container will decrease if the A) number of collisions with the container wall increases. B) number of moles of the gas increases. C) temperature of the gas decreases. D) volume of the container decreases.

Q: Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently cited to explain diffusion of a gas? A) The average kinetic energy of gas particles is proportional to the Kelvin temperature. B) Collisions of gas particles are elastic and total kinetic energy of the gas is constant. C) A gas consist of tiny particles moving in random straight line motion. D) The volume of the particles is negligible compared to the volume of the gas.

Q: Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently cited to explain compressibility of a gas? A) The average kinetic energy of gas particles is proportional to the Kelvin temperature. B) Collisions of gas particles are elastic and total kinetic energy of the gas is constant. C) A gas consist of tiny particles moving in random straight line motion. D) The volume of the particles is negligible compared to the volume of the gas.

Q: Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently cited to explain Charles' law? A) The average kinetic energy of gas particles is proportional to the Kelvin temperature. B) Collisions of gas particles are elastic and total kinetic energy of the gas is constant. C) A gas consists of tiny particles moving in random straight line motion. D) The volume of the particles is negligible compared to the volume of the gas.

Q: A 0.500 g sample containing Ag2O and inert material is heated, causing the silver oxide to decompose according to the following equation:2 Ag2O(s) -> 4 Ag(s) + O2(g)If 13.8 mL of gas are collected over water at 27C and 1.00 atm external pressure, what is the percentage of silver oxide in the sample? The partial pressure of water is 26.7 mm Hg at 27C.A) 12.5%B) 25.1%C) 50.1%D) 51.9%

Q: The ozone molecules in the stratosphere absorb much of the ultraviolet radiation from the sun, protecting life on Earth. At a certain altitude, the temperature of the stratosphere is 240 K and the partial pressure of ozone is 1.4 10-7 atm. Calculate the number of ozone molecules present in 1.00 L of atmosphere at that altitude. A) 2.1 1015 molecules of O3 B) 4.3 1015 molecules of O3 C) 8.0 1031 molecules of O3 D) 1.8 1032 molecules of O3

Q: In the laboratory, hydrogen gas is usually made by the following reaction:Zn(s) + 2 HCl(aq) ->H2(g) + ZnCl2(aq)How many liters of H2 gas, collected over water at an atmospheric pressure of 752 mm Hg and a temperature of 21.0C, can be made from 1.566 g of Zn and excess HCl? The partial pressure of water vapor is 18.65 mm Hg at 21.0C.A) 0.0428 LB) 0.573 LC) 0.585 LD) 0.599 L

Q: Hydrogen gas is collected over water in an inverted buret. If the atmospheric pressure is 745 mm Hg, the vapor pressure of water is 18 mm Hg, and a 15.0 cm-high column of water remains in the buret, the pressure of the hydrogen gas is A) 763 mm. B) 745 mm Hg. C) 727 mm Hg. D) less than 727 mm Hg.

Q: If the Earth's ozone (O3) layer has a total volume of 1.00 1020 km3, a partial pressure of 1.6 10-9 atm, and an average temperature of 230 K, how many ozone molecules are in the Earth's ozone layer? A) 2.3 1035 molecules B) 5.1 1035 molecules C) 2.3 1045 molecules D) 5.1 1045 molecules

Q: A 1.000 kg sample of nitroglycerine, C3H5N3O9, explodes and releases gases with a temperature of 1985C at 1.000 atm. What is the volume of gas produced?4 C3H5N3O9(l) -> 12 CO2(g) + 10 H2O(g) + 6 N2(g) + O2(g)A) 816.4 LB) 3878 LC) 5203 LD) 5919 L

Q: What is the total pressure in a 10.0 L flask which contains 0.127 mol of H2(g) and 0.288 mol of N2(g) at 20.0C? A) 0.306 atm B) 0.681 atm C) 0.693 atm D) 0.998 atm

Q: A balloon contains 0.76 mol N2, 0.18 mol O2, 0.031 mol He, and 0.026 mol H2 at 739 mm Hg. What is the partial pressure of O2? A) 19 mm Hg B) 23 mm Hg C) 130 mm Hg D) 560 mm Hg

Q: A 10.0-L flask containing He, 2.00 mole of Ar, and 3.00 mole of Ne has a total pressure of 24.5 atm at 25C. How many moles of He are in the flask? A) 5.00 mol B) 10.0 mol C) 114 mol D) 119 mol

Q: At STP how many liters of NH3 can be produced from the reaction of 6.00 mol of N2 with 6.00 mol of H2?N2(g) + 3 H2(g) -> 2 NH3(g)A) 44.8 LB) 89.6 LC) 134 LD) 269 L

Q: How many liters of SO3(g) are produced at 25C and 1.00 atm from the combustion of 1.00 kg of coal which is 1.00% S by weight? Assume all the sulfur in the coal ends up as SO3. A) 0.640 L B) 5.08 L C) 7.63 L D) 11.4 L

Q: How many grams of XeF6 are required to react with 0.579 L of hydrogen gas at 2.46 atm and 45C in the reaction shown below?XeF6(s) + 3 H2(g) -> Xe(g) + 6 HF(g)A) 3.65 gB) 4.46 gC) 13.4 gD) 40.2 g

Q: How many liters of oxygen are needed to exactly react with 27.8 g of methane at STP?CH4(g) + 2 O2(g) -> CO2(g) + 2 H2O(l)A) 19.5 LB) 39.0 LC) 77.6 LD) 85.0 L

Q: A lungful of air (500 mL) contains 4.1% CO2 by volume. How many grams of KO2(s) is needed to remove the CO2 from a lungful of air at STP according to the following reaction?4 KO2(s) + 2 CO2(g) -> 2 K2CO3(s) + 3 O2(g)A) 0.065 gB) 0.13 gC) 0.26 gD) 1.2 g

Q: When 15.0 g of zinc metal reacts with excess HCl, how many liters of H2 gas are produced at STP? A) 0.229 L B) 0.458 L C) 5.14 L D) 10.3 L

Q: At STP how many grams of Mg are required to produce 35 mL of H2 in the reaction shown below?Mg(s) + 2 HCl(aq) -> H2(g) + MgCl2(aq)A) 0.035 gB) 0.038 gC) 26 gD) 29 g

Q: The action of some commercial drain cleaners is based on the following reaction:2 NaOH(s) + 2 Al(s) + 6 H2O(l) -> 2 NaAl(OH)4(s) + 3 H2(g)What is the volume of H2 gas formed at STP when 4.32 g of Al reacts with excess NaOH?A) 2.39 LB) 3.59 LC) 5.38 LD) 5.87 L

Q: Chloroform is a volatile liquid once commonly used in the laboratory but now being phased out due to its ozone depletion potential. If the pressure of gaseous chloroform in a flask is 195 mm Hg at 25C and its density is 1.25 g/L, what is the molar mass of chloroform? A) 10.0 g/mol B) 76.3 g/mol C) 119 g/mol D) None of these

Q: Given three cylinders containing O2 gas at the same volume and pressure. Cylinder A is at -20C, cylinder B is at -15F, cylinder C is at 260 K. Which cylinder contains the largest mass of oxygen? A) cylinder A B) cylinder B C) cylinder C D) All cylinders contain the same mass of O2.

Q: Which of the following would have a density of 1.21 g/L at 7.0C and 0.987 atm? A) Ar B) N2 C) Ne D) O2

Q: One mole of which gas has the greatest density at STP? A) Ar B) N2 C) CO D) All three gases have the same density.

Q: What is the density of fluorine gas at STP? A) 0.590 g/L B) 0.848 g/L C) 1.55 g/L D) 1.70 g/L

Q: A 0. 286-g sample of gas occupies 125 mL at 60. cm of Hg and 25C. What is the molar mass of the gas? A) 5.9 g/mol B) 44 g/mol C) 59 g/mol D) 71 g/mol

Q: Cyanogen is a gas which contains 46.2% C and 53.8% N by mass. At a temperature of 25C and a pressure of 750 mm Hg, 1.50 g of cyanogen occupies 0.714 L. What is the molecular formula of cyanogen? A) CN B) C2N2 C) C3N4 D) C4N5

Q: What is the Celsius temperature of 100.0 g of chlorine gas in a 40.0-L container at 800 mm Hg? A) -91C B) 91C C) 182C D) 364C

Q: What is the volume of 10.0 g of argon gas at 157C and 2.50 kPa pressure? A) 1.29 L B) 3.53 L C) 131 L D) 358 L

Q: How many grams of O2 gas are there in a 5.00-L cylinder at 4.00 103 mm Hg and 23C? A) 17.3 g B) 34.7 g C) 446 g D) 2.63 104 g

Q: A gas occupies 22.4 L at STP and 14.5 L at 100C and 2.00 atm pressure. How many moles of gas did the system gain or lose? A) 0.06 moles gained B) 0.03 moles gained C) 0.03 moles lost D) 0.05 moles lost

Q: A steel bottle contains argon gas at STP. What is the final pressure if the temperature is changed to 115C? A) 0.704 atm B) 0.768 atm C) 1.30 atm D) 1.42 atm

Q: A 1.00 L flask contains nitrogen gas at 25C and 1.00 atm pressure. What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55C? A) 1.28 atm B) 2.01 atm C) 2.56 atm D) 3.29 atm

Q: A 75.0 L steel tank at 20.0C contains acetylene gas, C2H2, at a pressure of 1.39 atm. Assuming ideal behavior, how many grams of acetylene are in the tank? A) 4.33 g B) 6.01 g C) 113 g D) 1650 g

Q: A 1.75 L container filled with CO2 gas at 25C and 225 kPa pressure springs a leak. When the container is re-sealed, the pressure is 185 kPA and the temperature is 10C. How many moles of gas were lost? A) 0.0213 mol B) 0.463 mol C) 0.561 mol D) 2.16 mol

Q: How many molecules of N2 are in a 500.0 mL container at 780 mm Hg and 135C? A) 8.76 1021 B) 9.23 1021 C) 2.65 1022 D) 2.79 1022

Q: Three identical flasks contain three different gases at standard temperature and pressure. Flask A contains CH4, flask B contains CO2, flask C contains N2. Which flask contains the largest number of molecules? A) flask A B) flask B C) flask C D) All flasks contain the same number of molecules.