Ph

• Kinetics

  The studying of reaction rate & factors affecting it
• Reaction rate

  The velocity or the speed at which the reaction proceed, given by ± dc/dt which gives + the increase or - the decrease of concentration dC within a given time interval dt

  
• Reaction order

  The number of atoms or molecules whose concentration determine the reaction rate, showing how the concentration of reactant affects the reaction rate
• Factors affecting reaction rate

  • Concentration of reactant
  • Temperature
  • Catalysts
  • Presence of solvents
  • Light
  • pH
• Half life (t1/2)

  The time required for the drug to decompose to one half its original concentration
• Shelf life (t90%)

  The time required for the drug to lose 10% of its original concentration, or the time required for the drug to degrade to 90% of its original concentration
• Orders of reaction

  • Zero order
  • First order
  • Second order
  • Third order
• Zero order reaction

  Rate of reaction is independent on reactant concentration, -dc/dt=k0
• First order reaction

  Reaction rate depend on the 1st power of the concentration of single reactant, -dc/dt=k1[A]

  
• Second order reaction

  Reaction rate depend on the 2nd power of the concentration of reactants, -dc/dt=k2[A][B]
• Third order reaction

  Reaction rate depend on the 3rd power of the concentration of reactants, -dc/dt=k3[A]2[B]
• Arrhenius equation

  K = Ae^(-Ea/RT), where K is the specific reaction rate constant, A is the constant known as frequency factor or Arrhenius factor, Ea is the energy of activation, R is the molar gas constant, and T is the absolute temperature

  
• Arrhenius found that the speed of many reactions increase about 2 or 3 times with each 10°C rise in temperature
• Materials & equipment


  • Aspirin
  • Trisodium citrate
  • NaOH
  • Phenol red indicator
  • N/20 NaOH solution
  • Conical flasks (250cc, 150cc, 50cc)
  • Pipette
  • Burette
  • Three water baths
• Procedure


  1. Prepare the aspirin, trisodium citrate, and water mixture

  2. Take 10ml sample and titrate with N/20 NaOH to get the initial titration figure X

  3. Label 3 flasks with 40°C, 55°C, 70°C and place 80ml of the mixture in each

  4. Note the time and place the flasks in the water baths

  5. Take 10ml samples from each flask every 15 minutes for 1 hour and titrate with N/20 NaOH to get the end point figures Y1, Y2, Y3, Y4
• Tables

  • Table 1: Temp, Time, ml NaOH, c%, log c%
  • Table 2: Temp (°C), T, 1/T, K, log K
• Kinetics


  The studying of reaction rate & factors affecting it
• Reaction rate


  The velocity or the speed at which the reaction proceed, given by ± dc/dt which gives + the increase or - the decrease of concentration dC within a given time interval dt
• Reaction order


  The number of atoms or molecules whose concentration determine the reaction rate, showing how the concentration of reactant affects the reaction rate
• Factors affecting reaction rate

  • Concentration of reactant
  • Temperature
  • Catalysts
  • Presence of solvents
  • Light
  • pH
• Half life (t1/2)


  The time required for the drug to decompose to one half its original concentration
• Shelf life (t90%)


  The time required for the drug to lose 10% of its original concentration, or the time required for the drug to degrade to 90% of its original concentration
• Orders of reaction

  • Zero order
  • First order
  • Second order
  • Third order
• Zero order reaction

  Rate of reaction is independent on reactant concentration, -dc/dt=k0
• First order reaction

  Reaction rate depend on the 1st power of the concentration of single reactant, -dc/dt=k1[A]
• Second order reaction

  Reaction rate depend on the 2nd power of the concentration of reactants, -dc/dt=k2[A][B]
• Third order reaction

  Reaction rate depend on the 3rd power of the concentration of reactants, -dc/dt=k3[A]2[B]
• Arrhenius equation


  K = Ae^(-Ea/RT), where K is the specific reaction rate constant, A is the frequency factor, Ea is the energy of activation, R is the molar gas constant, and T is the absolute temperature

  
• Arrhenius found that the speed of many reactions increase about 2 or 3 times with each 10°C rise in temperature
• Materials & equipment


  • Aspirin
  • Trisodium citrate
  • NaOH
  • Phenol red indicator
  • N/20 NaOH solution
  • Conical flasks
  • Pipette
  • Burette
  • Three water baths
• Procedure


  1. Prepare the aspirin, trisodium citrate, and water mixture

  2. Take 10ml sample and titrate with N/20 NaOH to get the initial titration figure X

  3. Label 3 flasks with 40°C, 55°C, 70°C and place 80ml of the mixture in each

  4. Note the time and place the flasks in the water baths

  5. Take 10ml samples every 15 minutes for 1 hour and titrate with N/20 NaOH to get the end points Y1, Y2, Y3, Y4
• Tables


  • Table 1: Temperature, Time, ml NaOH, c%, log c%
  • Table 2: Temperature (°C), T, 1/T, K, log K
• Solubility product constant, Ksp


  The product of the molar concentrations of its ions in a saturated solution, each raised to the power that is the coefficient of that ion in the balanced chemical equation

  
• The more soluble a substance is, the higher the value of Ksp
• Solubility equilibrium


  When a slightly soluble ionic compound is added to water, some of it dissolves to form a solution, establishing an equilibrium between the pure solid and a solution of its ions

  
• The equilibrium expression is written without including the solid species
• Solving for Ksp


  1. Take the molarities of the products and multiply them

  2. If there are coefficients in front of any of the products, raise the product to that coefficient power (and multiply the concentration by that coefficient)

  
• Factors affecting Solubility and Ksp

  • Temperature effect: Endothermic reaction - temperature ↑, solubility ↑, Ksp ↑

  Exothermic reaction - temperature ↑, solubility ↓, Ksp ↓
• Calculating molar solubility of BaSO4


  Given Ksp = 1.07*10-10

  
• Common ion effect


  • Addition of common ion at constant temperature:

  Concentration of products ↑

  Reaction shifts backward (toward reactants) to get rid of excess products

  Reaction returns to first equilibrium state

  Ksp remains constant