Exp. 4 Standard Base solution and Stoichiometric

• Standard substance: The substance that we know concentration and quantity
• Standard solution: Prepared solution
• Standard substance

  1)Primary standard: High stability, low volatility, not absorb moisture, minimal change upon heat/light/oxygen

  ex: Na2CO3, KHC8H4O4
• Standard substance

  2) Secondary standard: Not stable, volatile, absorb moisture, prove to oxidation, sensitive to light and heat

  ex: HCl, NaOH, H2SO4, HNO3
• Standardization: titrate standard solution against primary standard substances to determine their exact concentration beforehand
• NaOH (Sodium Hydroxide) absorb water from air and reacts with CO2 (acidic)
• Standard NaOH may not have actual weight and inaccurate concentration.
• To make NaOH concentration accurate we should use acid primary standard substance

  1. Potassium Hydrogen phthalate KHC8H4O4 (KHP)
  2. Potassium Hydrogen Iodate (KHIO3)
• KHP: High purity, stable, mild acidic properties, react quickly with NaOH
• Structure of KHP

  
• Phenolphthalein: colorless -> pink (base)

  Methyl orange: Yellow -> red (acid)
• Decomposition of sodium bicarbonate

  A) NaHCO3 (s)

  B) NaOH(s)

  C) CO2(g)

  D) NaHCO3(s)

  E) Na2CO3(s)

  F) CO2(g)

  G) H2O(g)

  H) NaHCO3 (s)

  I) Na2O(s)

  J) CO2(g)

  K) H2O(g)

  
• $NaHCO_3$Baking Soda