Chemistry Exam Review Flashcards

Proportional Relationships in Chemistry

• Pressure (P) and Temperature (T), Temperature (T) and Volume (V), Pressure (P) and moles (n), and Volume (V) and moles (n) are directly proportional.
• Pressure (P) and Volume (V) are inversely proportional.

Phase Changes Classification

• Endothermic Processes:
  • Solid to liquid (melting)
  • Liquid to gas (vaporization)
  • Solid to gas (sublimation)
• Exothermic Processes:
  • Gas to liquid (condensation)
  • Liquid to solid (freezing)
  • Gas to solid (deposition)

Reaction Classification

• Endothermic Reactions:
  • Microwave popcorn popping
  • Boiling water
• Exothermic Reactions:
  • Burning a match
  • Burning rocket fuel
  • Chemical reaction in heat packs

Identifying Exothermic Reactions

• Exothermic reactions always have a negative change in enthalpy (-ΔH).

Chemical Changes Classification

• Endothermic Changes:
  • Chemical reactions that feel cold to the touch, like in cold packs used for injuries.
• Exothermic Changes:
  • Reactions like burning wood or using pocket hand warmers that feel hot upon reaction.

Collision Factors for Reactions

• Correct orientation during particle collisions is necessary.
• Sufficient collision energy is needed to exceed activation energy.

Factors Reducing Reaction Collisions

• Increasing the volume of the reaction vessel leads to fewer collisions.
• Lowering temperature reduces kinetic energy of particles.
• Decreasing reactant concentration results in fewer collisions.

Collision Likelihood in Reactions (A+B⟶C)

• Increases collisions:
  • Raising reaction temperature
  • Increasing concentration of reactant B
• No effect:
  • Lowering activation energy
• Decreases collisions:
  • Lowering temperature
  • Decreasing concentration of reactants

Influencing Chemical Reaction Rates

• Factors that increase reaction rates include:
  • Adding a catalyst
  • Changing the temperature
  • Altering the concentration of reactants
  • Modifying reactant surface area
  • Nature of the reactants

Reaction Rate Influences (A+B⟶AB)

• Factors that do not increase the rate of reaction:
  • Increasing concentration of product AB
  • Decreasing kinetic energy of molecules

Reaction Kinetics of Nitric Oxide and Oxygen

• Reaction: 2NO(g) + O2(g) ⟶ 2NO2(g)
• Doubling the concentration of oxygen doubles the reaction rate.
• Doubling concentrations of both reactants increases the reaction rate by a factor of eight.
• The reaction is first-order in oxygen and second-order in nitric oxide.