Lecture 10/22/99, Chapter 5, Section 8.

Announcements

Solution Concentration

  1. Introduce Concentration and Molarity
  2. Preparing a solution
    1. NiCl2*6H2O (CD-ROM d:, h:, internet)
      1. 8.320g NiCl2*6H2O
      2. 250.00 mL Volumetric Flask
        Mass of Compound (NiCl2*6H2O) 8.320 g
        MW (NiCl2*6H2O) 237.69 g mole-1
        Moles (NiCl2*6H2O) 0.0350 mole
        Volume (NiCl2*6H2O) 250.0 mL
        Concentration (NiCl2*6H2O) 0.140 mole liter-1
        What happens to ions? CD-ROM d: h: internet
        Concentration Ni2+ 0.140 mole liter-1
        Concentration Cl1- 0.280 mole liter-1
    2. How to produce 500.0 mL of 0.0100 M K2Cr2O7 (aq)
      Concentration (K2Cr2O7 (aq) ) 0.0100 M
      Volume (K2Cr2O7 (aq) ) 500.0 mL
      Moles (K2Cr2O7 (aq) ) 0.00500 mole
      MW (K2Cr2O7 (aq) ) 294.18 g mole-1
      mass (K2Cr2O7 (aq) ) 1.471 g
         
      Concentration K1+ 0.0200 M
      Concentration Cr2O72- 0.0100 M

Dilution

  1. 0.100 M K2Cr2O7 2.00 mL diluted to 500 mL
    1. CD-ROM ( d: h: internet )
      Initial Concentration (K2Cr2O7 (aq) ) 0.100 mole liter -1
      Volume (K2Cr2O7 (aq) ) 2.00 mL
      Moles (K2Cr2O7 (aq) ) 0.000200 mole
      Dilution Volume 500 mL
      Final Concentration (K2Cr2O7 (aq) ) 0.000400 mole liter-1
  2. 0.140 M NiCl2 (aq) solution
    1. Dilute 2.00 mL to 500 mL
      Initial Concentration NiCl2 0.140 mole liter-1
      Volume NiCl2 2.00 mL
      Moles NiCl2 2.8x10-4 mole
      Final Volume NiCl2 500 mL
      Final Concentration NiCl2 5.6x10-4 mole liter-1
    2. Dilute 5.00 mL to 500 mL
      Initial Concentration NiCl2 0.140 mole liter-1
      Volume NiCl2 5.00 mL
      Moles NiCl2 7.0x10-4 mole
      Final Volume NiCl2 500 mL
      Final Concentration NiCl2 1.4x10-3 mole liter-1



    3. Dilute 5.00 mL to 250 mL
      Initial Concentration NiCl2 0.140 mole liter-1
      Volume NiCl2 5.00 mL
      Moles NiCl2 7.0x10-4 mole
      Final Volume NiCl2 250 mL
      Final Concentration NiCl2 2.8x10-3 mole liter-1
    4. Dilute 5.00 mL to 1.00 L
      Initial Concentration NiCl2 0.140 mole liter-1
      Volume NiCl2 5.00 mL
      Moles NiCl2 7.0x10-4 mole
      Final Volume NiCl2 1.00 L
      Final Concentration NiCl2 7.0x10-4 mole liter-1

Practice problems.

  1. How do you prepare 100 mL of 0.150 M caffeine (C8N4O2H10)?
  2. How do you prepare 1.50 L of 3 M Mg2+ from Magnesium nitrate?