18.2

 Ch 18.2 outline Molarity

Molarity

• Concentration of a solution is a measure of the amount of solute that is dissolved in a given quantity of solvent.
• Dilute solutions is one that contains only low concentrations of solute
• Concentrated solution has high concentrations
• Molarity (M) is the number of moles of a solute dissolved per liter of solution.
  • a.k.a.  Molar concentration
  • Read as molar
• Determining molarity just calc the number of moles solute in 1L of solution
  • 1.Molarity (M) = moles solute____
  •                           Liters of solution

Making dilutions

• This is done by diluting the solution with solvent
• The number of moles of solute before dilution is equal to the number of moles after the dilution
• Dilution formula is
  • M1 x V1 = M2 x V2

Percent solutions

• If both the solute and solvent are liquids you express the solute as a percent of the solutions
• 20 mL of pure alcohol is diluted with water to a total volume of 100 mL, the final solution is 20% alcohol by volume.
  • Percent by volume (% (v/v)) = volume of solute   x 100
•                                                              solution volume 
• Percent mass volume is the mass of solute in 100 mL of solution
  • Percent (mass / volume) (% m/v) =   mass of solute (g)      x 100 
•                                                                     solution volume (mL)
• When using percentages be sure to express the units

complete the student response section