Quarterly Exam GC2

• Solution Stoichiometry


  Stoichiometry - the quantitative relationship among the amounts of reacting chemical species. It is the relationship among the number of moles of reactants and products as represented by a balanced chemical equation. In solution stoichiometry, volumes of solutions are measured and quantities calculated using the molarities of the solutions.
• Titration


  Titration - the process for finding the equivalence point (the point where the moles of H+ = moles OH- ions) in a neutralization reaction. It is the process of adding one reactant to another while monitoring the completeness of the reaction. At the equivalence point of titration, the amount of solute added precisely matches the amount of substance present. Endpoint of the titration - the point when the equivalence point is reached when some observable phenomenon occurred.
• Calculating moles of H+

  moles of H+ = M_acid x V_acid
• Calculating moles of OH-

  moles of OH- = M_base x V_base
• At equivalence point


  M_acid x V_acid = M_base x V_base, moles of H+ = moles of OH-
• Neutralization reaction


  When an acid and a base react to form water and a salt, and involves the combination of H+ ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7.
• How to Balance a Chemical Equation

  1. Step 1: The Unbalanced Chemical Equation

  2. Step 2: Make a List

  3. Step 3: Identifying the Atoms in Each Element

  4. Step 4: Multiplying the Number of Atoms

  5. Step 5: Placing Coefficients in Front of Molecules

  6. Step 6: Check Equation

  7. Step 7: Balanced Chemical Equation
• Colligative properties


  Properties that depend only on the number of solute particles in solution and not on the nature of the solute particles
• Raoult's Law


  When a nonvolatile solute is added to a solvent, the vapor pressure of the solution is lower than the vapor pressure of the pure solvent
• Vapor Pressure Lowering


  When salt is added to water, the vapor pressure of salt solution is lower than the vapor pressure of pure water
• According to Raoult's law, the partial pressure of a solvent over a solution (P1) is equal to the product of the mole fraction of the solvent in the solution (X1), and the vapor pressure of the pure solvent (P1°)
• Freezing Point Depression


  Addition of a nonvolatile solute to a solvent lowers its freezing point
• Boiling Point Elevation


  Addition of a nonvolatile solute to a solvent increases its boiling point
• Osmosis


  Movement of water molecules through a semipermeable membrane from a solution of lower concentration of solute to a solution that has higher concentration of solute
• Osmotic Pressure


  The pressure that prevents the flow of solution backwards
• van't Hoff factor (i)

  The ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass
• For non-electrolytes dissolved in water, the Van 't Hoff factor is 1
• How to determine the van't Hoff factor of substance that completely dissociate or ionize: (in the presence of water) 1. NaCl(s) → Na+ + Cl-, i = 2, 2. Ca(NO3)2 → Ca+2 + 2 NO3-, i = 3
• Solvent


  • Water
  • Benzene
  • Ethanol
  • Acetic acid
• Normal Freezing Point (°C)*


  • 0
  • 5.5<|-117.3
  • 16.6
• Kf (°C/m)


  • 1.86
  • 5.12
  • 1.99
  • 3.90
• Normal Boiling Point (°C)*

  • 100
  • 80.1
  • 78.4
  • 117.9
• Kb (°C/m)


  • 0.52
  • 2.53
  • 1.22
  • 2.93
• Thermodynamics


  The study of the relationships between heat, work, temperature, and energy
• Terms to be familiarized

  • Thermal
  • Energy
  • Radiant
  • Chemical
  • Potential
  • Kinetic
  • Thermo
  • Work
  • Surroundings
  • System
  • Heat
  • Product
  • Enthalpy
  • Reactant
  • Joule
• Thermochemistry


  The quantitative study and measurement of heat and enthalpy changes
• Enthalpy (H)


  Heat content
• Enthalpy change (ΔH) or Heat of reaction


  The amount of heat energy given out or taken in (absorbed) during a chemical reaction, measured in kilojoules (kJ)
• Types of reaction


  • Exothermic reaction (reaction that gives out heat to the surroundings)
  • Endothermic reaction (reaction that takes in heat from the surroundings)
• ΔH > 0


  Hproducts > Hreactants, endothermic reaction (ΔH is positive (+))
• ΔH < 0


  Hproducts < Hreactants, exothermic reaction (ΔH is negative (-))
• ΔH = 0


  Hproducts = Hreactants, no heat is lost or gained (ΔH is zero)
• First Law of Thermodynamics (Law of Conservation of Energy)


  Energy can be converted from one form to another with the interaction of heat, work and internal energy, but it cannot be created nor destroyed, under any circumstances
• q = +


  (heat is absorbed: endothermic)
• q = -


  (heat is released: exothermic)
• w = +


  (done on the system)
• w = -


  (done by the system)
• In chemistry, the concern is the system
• Compression (surrounding)


  ΔV = - (volume decreasing), W = + (work is done on the system), Volume decreases, Pressure increases
• Expansion (surrounding)


  ΔV = + (volume increasing), W = - (the gas is doing the work in the surrounding), Volume increases, Pressure decreases