WAYS OF EXPRESSING CONCETRATION

• Concentration


  General term that expresses the quantity of solute contained in a given amount of solution

  
• Solute


  Substance being dissolved in a solution
• Solvent


  Substance that dissolves the solute
• Concentrated solution


  Solution with large amount of solute
• Ways to express concentration of a solution


  • Percent by Mass
  • Percent by Volume
  • Percent by Mass/Volume
  • Molarity
  • Molality

  
• Percent by Mass


  Grams of solute per 100g of solution

  
• Percent by Mass


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• Percent by Volume


  Percentage of solute in a solution when solute and solvent are both liquids

  
• Percent by Volume


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• Percent by Mass/Volume


  Mass of solute divided by volume of solution, expressed as a percent

  
• Percent by Mass/Volume


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• Molarity


  Number of moles of solute dissolved in one liter of solution

  
• Molarity


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• Molality


  Number of moles of solute dissolved in one kilogram of solvent

  
• Molality


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• Why it is better to use molality in laboratory experiments than molarity

  Molality is more accurate when temperature changes
• Calculating molarity of a solution

  1. Dissolve 15 moles of glucose in enough water to make 2 L solution

  2. Concentration is 7.5 M

  
• Calculating molality of a solution


  Dissolve 8 moles of rock salt in 20 kg of water
• Calculating amount of sodium phosphate to make 2.5 molal solution

  Add 75 moles of Na3PO4 to 30 kg of water
• Calculating amount of potassium acetate to make 1.5 M solution

  Add enough KCH3COO to make 0.250 L of 1.5 M solution
• Calculating amount of benzoic acid to make 2.5 M solution

  Add 152.65 g of C6H5COOH to make 500 mL of 2.5 M solution
• Molarity (M) is the number of moles of solute per liter of solution

  
• Molality (m) is the number of moles of solute per kilogram of solvent