Key points in Gen chem 2

• Second law of thermodynamics states that the total entropy of an isolated system can never decrease over time.
• Significance of the second law of thermodynamics. It enables the prediction of the direction of spontaneous processes.
• The equation represents the relationship between the change in Gibbs free energy and the maximum work obtainable at constant temperature ∆G=∆H - T∆S
• Standard condition for Gibbs free energy change (∆G°) calculations: 298 K and 1 atm
• In a chemical equilibrium, when ∆G=0, the reaction is at equilibrium
• Factor that can affect the position of equilibrium in a chemical reaction: Temperature, Pressure, Catalyst
• A decrease in volume affect the equilibrium in a gaseous reaction at constant temperature: Shifts the equilibrium to the side with fewer gas molecules.
• The effect of a decrease in temperature on the equilibrium of an exothermic reaction: Shifts the equilibrium to the left.
• In a reversible chemical reaction that is at equilibrium, the reaction shifts to the right when you add more product
• Le Chatelier's Principle state If a system at equilibrium is subjected to a change in temperature, pressure, or concentration, the system will shift its equilibrium position to counteract the change.
• When adding a catalyst to a reaction at equilibrium, what change occurs according to Le Chatelier's Principle: The equilibrium shifts to the left.
• Disturbance in Le Chatelier's Principle •Change in pressure •Change in concentration. •Change in temperature
• Factor that can affect the equilibrium of a reaction

  • Concentration

  
  

  • Temperature

  
  

  •  Catalysts
• Catalysts have no effect on chemical equilibrium.
• An increase in pressure will favor the side of the reaction with higher number of moles of gas
• A Bronsted-Lowry base in a chemical reaction accepts protons
• An acid is a substance that can donate a proton to another substance. This is the definition of acid and base according to Bronsted and Lowry
• Substances that are acids in the Bronsted-Lowry theory:

  1. HClO4 (perchloric acid)

  2. H2SO4 (sulfuric acid)

  3. HCl (hydrochloric acid)
• A characteristic of a weak base is low concentration of OH- ions in solution
• Household ammonia is a base.
• pH 7 is neutral
• Stronger acid than H₂O is HCI
• a solution with a pOH of 5 is basic
• In the reaction: H₂O + H₂O → H3O↑+ + OH↑-, water is acting as an acid
• In the reaction H2SO4 + H₂O → H3O↑+ + HSO4- , which species is the conjugate base is HSO4-
• The role of the oxidizing agent in a redox reaction: It accepts electrons from the species being reduced
• responsible for the gain of electrons in a redox reaction: oxidizing agent
• A good reducing agent is magnesium
• Mg + 2HCl → MgCl₂ + H₂: The oxidizing agent is HCl
• Example of redox reaction: rusting iron
• During the process of electrolysis, where do positive ions move towards: anode
• Substance can undergo electrolysis is salt water
• The purpose of the salt bridge in a galvanic cell is to provide medium for the movements of ions
• Importance of acids and bases: they are important in regulating pH levels in biological systems
• A base is a substance that can accept a proton.
• In the reaction, NH3 + H2O → NH4+ + OH-, which species is the conjugate acid? It is NH4+