Exam 11: Properties of Gases

How many liters of pure oxygen gas, measured at STP, are required for the complete combustion of 11.2 L of methane gas (CH₄), also measured at STP?

A gas mixture is 50.00% helium and 50.00% methane, by volume. What is the percent, by weight, of methane in the mixture?

An open-end manometer constructed from a U-shaped tube was operated using an oil that has a density of 1.088 g mL⁻¹. In a particular measurement, the level in the end connected to the gas vessel, on which the experiment was being conducted, measured 76.2 cm above the U-neck, while the level in the open end was 23.8 cm above the U-neck. The outside air pressure in the laboratory was measured as 754 torr. What is the pressure in the gas vessel?Hint: The density of mercury is 13.533 g mL^{−1 at room temperature.}

Two moles of carbon dioxide gas at 35°C are heated to 250°C in a container while the volume is kept constant. The density of the gas in the container will

The standard reference conditions for gases has the values

A chemical reaction is shown: 2NO(g)+ O₂(g)? 2NO₂(g). How many liters of pure oxygen gas, measured at STP, are required for the complete reaction with 8.82 L of NO(g), also measured at STP?

Calculate the volume occupied by 25.4 g of methane gas (CH₄)at 1.63 atm and 35°C?

A sample of a gas in a cylindrical chamber with a movable piston occupied a volume of 11.60 liters when the pressure was 9.97 × 10⁴ Pa and the temperature was 24.9°C. The volume of the system was readjusted to 8.50 liters by moving the piston. What is the pressure exerted on the surface of the piston by the gas if the temperature of the system remained constant?

A general chemistry student needs to heat a liquid. Not wanting to spill anything, he puts a stopper on the solution flask and then heats the solution to 220 °C. While working in another part of the lab, the student hears an explosion and rushes over to find his flask broken into dozens of pieces. What was the likely cause of the explosion?

A gas sample containing 0.2820 moles of a compound is trapped in a vessel at a temperature of 25.2 °C and a pressure of 642.0 torr. What is the volume of the vessel?

Calculate the density of oxygen gas at 1.000 atm and 25.00 °C.

A sample of a gas occupies a volume of 185.5 mL at 20.2 °C and 0.945 atm. What pressure would it exert if it was transferred to a gas bulb with a volume of 255.5 mL in which the temperature is increased to 34.5 °C?

A 0.801 g sample of an unknown organic gas occupies 391 mL at 144°C and 950 mm Hg. The empirical formula of the compound was determined to be CH₂. What is the molecular formula of the compound?Hint: Apply the procedure for finding molecular formulas from Chapter 3.

1.000 atm of dry nitrogen, placed in a container having a pinhole opening in its side, leaks from the container 2.28 times faster than does 1.000 atm of an unknown gas placed in this same apparatus. Which of the following species could be the unknown gas?

A gas sample weighing 4.48 grams occupies a volume of 2.15 L at STP. What is the molecular mass of the sample?

Explain how real gases differ from ideal gases on the molecular level.

The average speed at which a methane molecule effuses at 28.5 °C is 631 meters per second. The average speed at which an argon molecule effuses at this same temperature should therefore be

A sample gas mixture occupies a volume of 1.446 liters when the temperature is 155.0 °C and the pressure is 714.8 torr. The mole fraction of methane in this sample is 0.2250. How many methane molecules are there in the sample?Hint: Use the ideal gas law and dimensional analysis.

The barometric pressure in a cavern was measured using a mercury barometer. A value of 74.2 cm of Hg was obtained. How many atmospheres is this?

A gas sample weighing 6.480 grams occupies a volume of 3.550 liters at STP. What is the apparent molecular mass of the sample?