AP/IB ChemistryName:

Ch. 5 Test

Multiple Choice: Circle the letter of the best answer choice.

1.You are holding two balloons, an orange balloon and a blue balloon. The orange balloon is filled with neon gas and the blue balloon is filled with argon gas. The orange balloon has twice the volume of the blue balloon. Which of the following best represents the mass ratio of Ne:Ar in the balloons?

  1. 1:1
  2. 1:2
  3. 2:1
  4. 1:3
  5. 3:1

2.Which conditions of P, T, and n respectively are most ideal?

  1. high P, high T, high n
  2. low P, low T, low n
  3. high P, low T, high n
  4. low P, high T, high n
  5. low P, high T, low n

3.Given a cylinder of fixed volume filled with 1 mol of argon gas, which of the following is correct? (Assume all gases obey the ideal gas law)

  1. If the temperature of the cylinder is changed from 25 oC to 50 oC, the pressure inside the cylinder will double.
  2. If a second mole of argon is added to the cylinder, the ratio T/P would remain constant.
  3. A cylinder of identical volume filled with the same pressure of helium must contain more atoms of gas because He has a smaller atomic radius than argon.
  4. Two of the above.
  5. None of the above.

4.A 4.37 gram sample of a certain diatomic gas occupies a volume of 3.00-L at 1.00 atm and a temperature of 45oC. Identify the gas: [REPEAT OF FR #5]

  1. F2
  2. N2
  3. H2
  4. O2
  5. Cl2

Free Response: Answer the following free response question on your own piece of paper and attach to this page.

5.A container with a movable piston is filled with an ideal gas to a pressure of 15.0 atm at 25 oC. Under these conditions, the piston is held at a volume of 3.5 L.

(a)Determine the number of moles of gas occupying the container.

(b)Determine the pressure in the container if the piston is held at constant volume and the gas sample is heated to 100.oC:

(c)If the piston is then allowed to move, what volume would the gas in part (b) need to occupy if the pressure is to be increased to 25.0 atm?

6You have a 400-mL container containing 55.0% helium and 45.0% argon by mass at 25oC and 1.5 atm total pressure.

(a)What is the partial pressure of helium at these conditions?

(b)The container is heated to 100.oC at constant volume. Calculate the new total pressure in the container.

(c)Calculate the ratio of PHe: PAr at the conditions from part (b)

7.A 3.31 g sample of lead nitrate (Mr = 331 g/mol) is heated in an evacuated cylinder with a volume of 1.62 L. The salt decomposes to when heated according to the unbalanced equation:

Pb(NO3)2(s)  PbO(s) + NO2(g) + O2(g)

Assuming complete decomposition, what is the pressure in the cylinder after decomposition and cooling to a temperature of 300. K? You may assume the solid lead oxide product takes up negligible volume.

8Four identical 1.0-L flasks contain the gases helium, chlorine, methane, and ammonia, each at 0oC and 1 atm pressure. Explain your responses to the following questions using appropriate chemical concepts.

(a)Rank the gases in order of increasing density.

(b)Rank the gases in order of increasing average velocity.

(c)Which gas sample has the greatest number of molecules?

(d)For which gas are the molecules diatomic?

(e)For which gas are the collisions considered elastic?

(f)For which gas do the molecules have the smallest average kinetic energy?