Unit 4Test--Motion and Masses . . . All About Gases

True/False

  1. 25 oC = 248 K

  2. Two equally sized containers at the same temperature and pressure will hold the same number of gas particles.

  3. At the same temperature, molecules of H2 will have the same average speed as molecules of He.

  4. At the same temperature, molecules of H2 will have the same average kinetic energy as molecules of He.

  5. In the reaction, N2O4 2 NO2, one liter of N2O4 will produce 2 liters of NO2 at STP.

Multiple Choice (Choose the best answer.)

  1. The pressure of a gas is measured using a closed-end manometer. (Shown at right.) Atmospheric pressure is 756 mm Hg. The mercury on the left of the manometer is 10 mm lower than on the right. The pressure of the gas is.

    -10 mmHg

    10 mmHg

    746 mmHg

    756 mmHg

    76 mmHg

    Questions 2 and 3 refer to the graphs below:

  2. Which graph shows the relationship between pressure and volume? (Pressure on Y axis--Volume on X axis)

  3. Which graph shows the relationship between volume and temperature? (Volume on Y axis--Temperature on X axis)

  4. Which one of the following is a FALSE statement concerning a fixed mass of a gas?

    P1V1 = P2V2 (Temp. is constant.)

    P1 / T1 = P2 / T2 (Vol. is constant.)

    V1 / T1 = V2 / T2 (Press. is constant.)

    As pressure increases, volume decreases at constant temp.

    As the temperature increases, volume decreases at constant pressure.

  5. A container of gas at 20 oC is heated. What temperature must be reached if the gas pressure is to be doubled?

    40 oC

    273 oC

    313 oC

    400 oC

    None of These

    A flask is filled with 16.0 g of methane (CH4) and 16.0 g of helium (He). The total pressure of the two gases is 2,000 mm Hg.. You may assume that the two gases do not react with each other. Use this information to answer questions 6 & 7.

  6. The number of moles of helium in the flask is

    1.0 mole

    2.0 moles

    4.0 moles

    8.0 moles

    16.0 moles

  7. The partial pressure of helium in the flask is _____ mm Hg.

    1,500

    1,000

    1,200

    1,600

    2,000

  8. If one liter of a gas at STP has a mass of 5.80 grams, its molar mass is:

    2.2 g

    130 g

    58 g

    85.4 g

    0.26 g

  9. A gas occupies 40.0 mL at -123 oC. What volume does it occupy at 27 oC?

    8.80 mL

    20.0 mL

    80.0 mL

    182 mL

    821 mL

  10. In the experiment where you reacted magnesium metal and hydrochloric acid, a number of students wrote that a possible error would be using too much HCl. This is not a likely error because:

    Mg was the limiting reactant.

    HCl was not a reactant.

    2 mol of HCl was required to react with 1 mol Mg.

    None of these.

    All of these.

Problem Solving (Show All Work. Use Correct Units And Significant Figures.)

1. Ethane, C2H6, has a molecular weight of 30.0 g/mol.

a) What is the density in g/L at STP?
b) What volume would 10.0 L of ethane at STP occupy at 400 oC and 2 atm?

 

 

2. 30.0 L of methane at STP burned to form carbon dioxide gas and water according to the (unbalanced) equation shown below. How many grams of water will result?

CH4 (g) + O2 (g ) CO2 (g) + H2O (g)




3. Figure 1 below shows 10 molecules of a gas in a cylinder with a movable piston at a certain temperature and pressure. The speeds of the particles are indicated by "tails." Figure 2 shows a graph of the distribution of the speeds of the 10 gas molecules shown in Figure 1.

a) Draw a picture in the space below Figure 1 to show any changes that might occur if the absolute temperature of the system were increased significantly.

b) Draw a sketch of in the space below Figure 2 to show any changes that might occur in the graph if the absolute temperature of the system were increased significantly.

























Home Page|Homework|Safety Rules|Schedule|Supplies|Tests