Adv Chem Unit 09 Mock Exam

Which statement best explains why a confined gas exerts pressure?

• the molecules are in random motion

• the molecules do NOT attract one another

• the molecules collide with the container walls

• the molecules increase their kinetic energy with increase in temperature

Identify the correct statement regarding the Kinetic Molecular Theory. 

• As temperature decreases, this causes velocity to decrease.
• Gas particles are closely associated with each other.
• Intermolecular forces are strong.
• Collisions are effective (inelastic).

Which of the following statements about the Kinetic-Molecular Theory of gases is false?

• Gases consist of molecules in continuous, random motion.

• The average kinetic energy of a gas molecule is independent of the temperature.

• Collisions between molecules are elastic.

• The distance between molecules is much larger than the diameter of each molecule.

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4

Based on the Maxwell-Boltzmann distribution of the fraction of molecules in a gas sample plotted against the molecular speed of the molecules, which of the following statements does NOT relate to the data presented?

• The hydrogen gas has the fastest speed due to the low molecular mass of the gas.
• Polarity of a gas does not affect the average molecular speed of the gas in the mixture.
• Oxygen has the highest fraction of molecules overall in the gas mixture.
• Water must be in the vapor phase not the liquid phase for this particular graph.

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4

The N₂ gas particles in  the container shown is initially at 27°C.  The lengths of the arrows represents the speeds of the particles.  Which of the following diagrams best represents the particles when the vessel is heated to 127°C?

• A
• B
• C
• D

Tags

NGSS.HS-PS1-5

Consider the mixture of gases pictured.  
Which of the gases move at a slower average velocity?

• Helium because it has a smaller molar mass. 
• Neon because it has a larger molar mass. 
• The both move at the same average velocity because they are at the same temperature. 

• It is impossible to tell without knowing the number of moles of each gas.

Tags

NGSS.HS-PS3-2

Consider the mixture of gases pictured.  
Helium has the _________ AVERAGE KINETIC ENERGY as neon because it has _____________.

• SAME:
  THE SAME TEMPERATURE
• SAME:
  THE SAME PRESSURE
• HIGHER:
  THE LOWER MOLAR MASS
• LOWER:
  THE HIGHER MOLAR MASS

Tags

NGSS.HS-PS3-2

A rigid vessel is connected to four separate 2.00 liter gas cylinders. Each cylinder contains a separate, diatomic gas at room temperature. When the gases are combined and held at room temperature, which of the following most accurately describes what happens in the reaction vessel?

• All of the gases immediately diffuse at the same rate, causing the kinetic energy of the substances to increase.
• The heavier diatomic gases diffuse slower than the lighter diatomic gases, causing a heterogeneous mixture in the new system.
• The rate of diffusion differs for each gas, but the overall kinetic energy of the system remains constant.
• The lightest mass gas is unable to diffuse into the new system due to the increased pressure by the heavier gases causing only three of the four gases to mix in the new container.

At standard temperature, a gas has a volume of 332 mL. The temperature is then increased to 128°C, and the pressure is held constant. What is the new volume?

• Unable to determine without initial temperature. 
• 226mL
• 488mL
• 708mL

How does the average kinetic energy of the helium atoms in Container A compare to the average kinetic energy of the helium atoms in Container B?

• The average kinetic energy of helium atoms in Container A is half the average kinetic energy of helium atoms in Container B because the pressure in Container A is half the  pressure in Container B. Average kinetic energy is directly related to pressure.
• The average kinetic energy of helium atoms in Container A is half the average kinetic energy of helium atoms in Container B because the number of moles in Container A is half the number of moles in Container B. Average kinetic energy is directly related to number of moles.
• The average kinetic energy of helium atoms in Container A is the same as the average kinetic energy of helium atoms in Container B because the volumes of the containers are the same. Average kinetic energy is directly related to volume. 
• The average kinetic energy of helium atoms in Container A is the same as the average kinetic energy of helium atoms in Container B because the temperatures of the gases in the containers are the same. Average kinetic energy is directly related to temperature.