## CHM102 MasteringChemistry Ch. 10

On a rainy day, a barometer reads 737 mmhg . Convert this value to atmospheres. 1 atm = 760 mmHg | 0.970 atm |

A closed container is filled with oxygen. The pressure in the container is 365 kPa . What is the pressure in millimeters of mercury? 1 atm = 101,325 Pa | 2740 mmHg |

Which of the following statements are true? Check all that apply. | There are gas molecules that move slower than the average. There are gas molecules that move faster than the average. The average kinetic energy of gas molecules increases with increasing temperature. The average speed of gas molecules increases with increasing temperature. |

Which statements about a sample of gas containing molecules of different masses are true? | More-massive gas molecules in the sample have lower rms speed than less-massive ones. |

Calculate the volume of the gas when the pressure of the gas is 1.50 atm at a temperature of 298 K. There are 130. mol of gas in the cylinder. The value for the universal gas constant R is 0.08206 L?atm/(mol?K) . | 2119 L |

Consider three gases all at 298 K: HCl, H2, and O2. List the gases in order of increasing average speed. | HCl, O2, H2 |

The pressure inside a hydrogen-filled container was 2.10 atm at 21 ?C. What would the pressure be if the container was heated to 87 ?C ? P1V1 = P2V2 | 2.57 atm |

At standard temperature and pressure (0 ?C and 1.00 atm ), 1.00 mol of an ideal gas occupies a volume of 22.4 L. What volume would the same amount of gas occupy at the same pressure and 95 ?C ? PV=nRT | 30.2 L |

A certain amount of chlorine gas was placed inside a cylinder with a movable piston at one end. The initial volume was 3.00 L and the initial pressure of chlorine was 1.65 atm . The piston was pushed down to change the volume to 1.00 L. Calculate the final pressure of the gas if the temperature and number of moles of chlorine remain constant. P1V1 = P2V2 | 4.95 atm |

In an air-conditioned room at 19.0 ?C, a spherical balloon had the diameter of 50.0 cm. When taken outside on a hot summer day, the balloon expanded to 51.0 cm in diameter. What was the temperature outside in degrees Celsius? Assume that the balloon is a perfect sphere and that the pressure and number of moles of air molecules remains the same. V1/T1 = V2/T2 | 36.9 degrees C |

A cylinder with a movable piston contains 2.00 g of helium, He, at room temperature. More helium was added to the cylinder and the volume was adjusted so that the gas pressure remained the same. How many grams of helium were added to the cylinder if the volume was changed from 2.00 L to 2.50 L ? (The temperature was held constant.) V1/n1 = V2/n2 | 0.0500 g |

Which of the following relationships are correct according to Boyle’s law. Check all that apply. | V?1P P?1V |

Standard temperature and pressure (STP) are considered to be 273 K and 1.0 atm. Predict which of the following changes will cause the volume of the balloon to increase or decrease assuming that the temperature and the gas filling the balloon remain unchanged. | volume increases: -balloon filled with helium under water at 1.15 atm is released and floats to the surface, which is at STP. -balloon filled with helium at STP floats into the atmosphere where the pressure is 0.5 atm. volume decreases: volume is unchanged: |

A certain gas is present in a 15.0 L cylinder at 2.0 atm pressure. If the pressure is increased to 4.0 atm the volume of the gas decreases to 7.5 L . Find the two constants ki, the initial value of k, and kf, the final value of k, to verify whether the gas obeys Boyle’s law. PV = k | 30,30 |

If a certain gas occupies a volume of 12 L when the applied pressure is 6.0 atm , find the pressure when the gas occupies a volume of 3.0 L . P1V1 = P2V2 | 24 atm |

When heated, calcium carbonate decomposes to yield calcium oxide and carbon dioxide gas via the reaction CaCO3(s) ? CaO(s) + CO2(g) What is the mass of calcium carbonate needed to produce 75.0 L of carbon dioxide at STP? PV=nRT | 335 g |

Butane, C4H10, is a component of natural gas that is used as fuel for cigarette lighters. The balanced equation of the complete combustion of butane is 2C4H10(g) + 13O2(g) ? 8CO2(g) + 10H2O(l) At 1.00 atm and 23 ?C, what is the volume of carbon dioxide formed by the combustion of 2.80 g of butane? PV=nRT | 4.69 L |

How long does it take a person at rest to breathe one mole of air if the person breathes 83.0 mL/s of air that is measured at 25 ?C and 755 mmHg? | 296 s |

Typically, when a person coughs, he or she first inhales about 2.50 L of air at 1.00 atm and 25 ?C. The epiglottis and the vocal cords then shut, trapping the air in the lungs, where it is warmed to 37 ?C and compressed to a volume of about 1.70 L by the action of the diaphragm and chest muscles. The sudden opening of the epiglottis and vocal cords releases this air explosively. Just prior to this release, what is the approximate pressure of the gas inside the lungs? | 1.53 atm |

Helium-oxygen mixtures are used by divers to avoid the bends and are used in medicine to treat some respiratory ailments. What percent (by moles) of He is present in a helium-oxygen mixture having a density of 0.528 g/L at 25 ?C and 721 mmHg? | 65.7 % He |

Three gases (8.00 g of methane, CH4, 18.0 g of ethane, C2H6, and an unknown amount of propane, C3H8) were added to the same 10.0-L container. At 23.0 ?C, the total pressure in the container is 4.60 atm . Calculate the partial pressure of each gas in the container. P1 = X1 × Ptotal | 1.21, 1.45, 1.94 atm |

A gaseous mixture of O2 and N2 contains 32.8 % nitrogen by mass. What is the partial pressure of oxygen in the mixture if the total pressure is 245 mmHg ? P1 = X1 × Ptotal | 157 mmHg |

A 3.00-L flask is filled with gaseous ammonia, NH3. The gas pressure measured at 28.0 ?C is 2.25 atm . Assuming ideal gas behavior, how many grams of ammonia are in the flask? PV=nRT | 4.64 g |

If 1.00 mol of argon is placed in a 0.500-L container at 30.0 ?C , what is the difference between the ideal pressure (as predicted by the ideal gas law) and the real pressure (as predicted by the van der Waals equation)? For argon, a=1.345(L2?atm)/mol2 and b=0.03219L/mol. | 2.0 atm |

The density of ammonia gas in a 4.32 L container at 837 torr and 45.0 °C is __________ g/L. | 0.719 |

Nitrogen gas behaves more like an ideal gas as the temperature increases. | True |

How would you expect the pressure of a gas to change if suddenly the intermolecular forces were repulsive rather than attractive? | increase |