Potential energy diagram

Question

Question 1: On a potential energy diagram, the activation energy is greatest under which of the following conditions?

• The potential energy of the products is greater than the reactants and the change in enthalpy is positive.
• The potential energy of the products is less than the reactants and the change in enthalpy is positive.
• The potential energy of the products is greater than the reactants and the change in enthalpy is negative.
• The potential energy of the products is less than the reactants and the change in enthalpy is negative.

Question 2: How would a system in which both matter and energy are exchanged freely between the system and the surroundings be classified?

• an open system
• an isolated system
• a closed system
• an integrated system

Question 3: What is the oxidation number of sulfur (S) in magnesium sulfate (MgSO₄)?

• +2
• +3
• +6
• +7

Question 4: Which substance will require more energy to heat if all the samples have the same mass?

• Lead
• Magnesium
• Iron
• Aluminum

Question 5: Which of the following describes what occurs as a liquid becomes a solid?

• A physical change occurs; the particles of the liquid vibrate faster and their kinetic energy increases.
• A physical change occurs; the particles of the liquid vibrate more slowly and their kinetic energy decreases.
• A chemical change occurs; the particles of the liquid vibrate faster and their kinetic energy increases.
• A chemical change occurs; the particles of the liquid vibrate more slowly and their kinetic energy decreases.