Home Chapter 10: Gases Quiz 1

# Quiz 1

This activity contains 12 questions.

## 1.9 moles of gas are in a flask at 21°C and 697 torr. The flask is opened and more gas is placed in the flask. The new pressure is 795 torr and the temperature is now 26°C. How many moles of gas are now in the flask?

 1.7 moles 2.1 moles 2.2 moles 1.8 moles 1.6 moles

## 16.8 mol of a gas occupies 228 L at 30°C. If the temperature is lowered to 10°C at constant pressure, what is the final volume?

 76 L 2151 L 244 L 213 L 684 L

A chemist is studying the properties of a gas occupying a bulb connected to a U-tube manometer, the other end of which is open to the air, as shown in the figure below. The gas in the bulb is in contact with a solid chemical, with which it may be reacting. The observation is made that the level of the mercury in the U-tube on the side of the bulb is gradually falling over time. Which of the following cannot be a potential cause for this?

 The gas is reacting with the solid to produce one mole of product gas for every mole of reactant gas consumed. However, the product gas has a higher molar mass. A reaction is occurring inside the bulb that is increasing the number of moles of gas. The temperature of the gas inside the bulb is increasing. The prevailing atmospheric pressure is falling. The solid is subliming (evaporating).

A gas vessel is attached to an open-tube manometer filled with a nonvolatile liquid of density 0.993 g/mL, as shown below. The difference in heights of the liquid in the two sides of the manometer is 32.3 cm when the atmospheric pressure is 765 mm Hg. Given that the density of mercury is 13.6 g/mL, what is the pressure in atm of the enclosed gas?

 0.976 atm 1.04 atm 6.83 atm 1.00 atm 1.01 atm

## Consider four identical 1.00-L flasks containing the following gases each at 0°C and 1 atm pressure: H2, O2, NH3, SO2. Which sample has the most molecules?

 NH3 same for all gases SO2 H2 O2

## Consider four identical 1.00-L flasks containing the following gases each at 25°C and 1 atm pressure: H2, O2, NH3, SO2. For which gas does the molecules have the highest-average kinetic energy?

 NH3 SO2 H2 O2 same for all gases

## Consider the following reaction: 2NO + O2 --> 2NO2 200. mL of NO at STP is reacted with 500. mL of O2 at STP. Calculate the partial pressure of NO2 after the reaction goes to completion. Assume a constant volume.

 0.500 atm 0.333 atm 0.286 atm 0.400 atm 1.00 atm

Hydrogen gas can be produced by the reaction of Al metal with aqueous HCl according to the equation below. How many liters of H2 gas collected dry at 700 torr and 27°C can be produced by the reaction of 0.50 g of Al with an excess of HCl?

2Al(s) + 6HCl(aq) ----> 2AlCl3 + 3H2(g)

 20 L 0.49 L 9.8 x 10-4 L 0.74 L 0.067 L

## Nitrogen and hydrogen are reacting in a sealed vessel in a proper stoichiometric ratio to produce ammonia. As the reaction proceeds at a constant temperature and volume, the pressure inside the reaction vessel

 increases. does not change. decreases.

## The density of an unknown element in the gaseous state is 1.60 g L-1 at 300 K and 1 atm. Which of the following could be the element: He, Ne, Ar, O2, Cl2?

 O2 Ar Ne He Cl2

## Which of the following pairs involve variables that are inversely proportional?

 n, T V, n P, n P, T V, T

## Which of these paint-solvent vapors is likely to diffuse most rapidly through the air in a room?

 ethyl acetate (C4H8O2) methyl ethyl ketone (C4H8O) toluene (C7H8) These would all diffuse at the same rate. acetone (C3H6O)