Unit 4 Practice Problems

A rigid cylinder with a movable piston contains a sample of helium gas. The temperature of the gas is held constant as the piston is pulled outward. Which graph represents the relationship between the volume of the gas and the pressure of the gas?

• 
• 
• 
• 

What is the total amount of heat required to completely melt 347 grams of ice at its melting point?

• 334 J

• 1450 J

• 116000 J

• 784000 J

Which statement describes particles of an ideal gas, based on kinetic molecular theory?

• Gas particles are separated by distances smaller than the size of the gas particles.

• Gas particles do not transfer energy to each other when they collide.

• Gas particles have no attractive forces between them.

• Gas particles move in predictable, circular motion.

One mole of liquid water and one mole of solid water have different

• masses

• properties

• empirical formulas

• gram-formula masses

Which element has a melting point higher than the melting point of rhenium? (use Table S)

• iridium

• osmium

• tantalum

• tungsten

A sample of water is boiling as heat is added at a constant rate. Which statement describes the potential energy and the average kinetic energy of the water molecules in this sample?

• The potential energy decreases and the average kinetic energy remains the same.

• The potential energy decreases and the average kinetic energy increases.

• The potential energy increases and the average kinetic energy remains the same.

• The potential energy increases and the average kinetic energy increases.

At STP, which sample contains the same number of molecules as 3.0 liters of H₂(g)? (Avagadro's Law)

• 1.5 L of NH₃(g)

• 2.0 L of CO2(g)

• 3.0 L of CH₄(g)

• 6.0 L of N2(g)

A sample of hydrogen gas will behave most like an ideal gas under the conditions of

• low pressure and low temperature

• low pressure and high temperature

• high pressure and low temperature

• high pressure and high temperature

The heating curve below represents a sample of a substance starting as a solid below its melting point and being heated over a period of time.

Which statement describes the energy of the particles in this sample during interval DE?

• Both potential energy and average kinetic energy increase.

• Both potential energy and average kinetic energy decrease.

• Potential energy increases and average kinetic energy remains the same.

• Potential energy remains the same and average kinetic energy increases.

A rigid cylinder with a movable piston contains a sample of gas. At 300. K, this sample has a pressure of 240. kilopascals and a volume of 70.0 milliliters. What is the volume of this sample when the temperature is changed to 150. K and the pressure is changed to 160. kilopascals?

• 35.0 mL

• 52.5 mL

• 70.0 mL

• 105 mL