Solutions and Concentrations Notes Page 5
Feb 24, 2016
Solutions and Concentrations
Notes Page 5
SOLUTIONS
A homogenous mixture of two or more substances
2 PARTS OF A SOLUTION• SOLUTE• A solute is the dissolved substance in a solution.
Sugar in sodaCarbon dioxide in sodaSalt in salt water
• SOLVENT• A solvent is the dissolving medium in a solution. • Water in salt water
Water in soda
Molarity = concentration•Amount of substance (mol)•Volume of mixture (L)
•Unit = mol/L or M•1.0 M = 1 molar •12.0 M = 12 molar
solUTE over solVENT
Example 1•1.5 mol of NaCl are dissolved in 1 L of water. What is the molarity of the solution?
•1.5 mol NaCl = 1.5 mol/L or 1.5 M•1 L H2O
Example 2•100 g of NaCl are dissolved in 1 L of water.
What is the molarity of the solution?
•100 g NaCl |1 mol NaCl = 1.71 mol 58.44 g NaCl
•1.71 mol NaCl = 1.71 M 1 L
Example 3
•100 g of NaCl are dissolved in 250 mL of water. What is the molarity of the solution? •100 g NaCl |1 mol NaCl = 1.71mol• 58.44 g NaCl •250 mL / 103 mL = 0.25 L•1.71 mol NaCl = 6.84 M 0.25 L
Example 4• How many moles of NaCl are in 500 mL of a 0.25 M solution? • Basic formula: M = mol L • Convert: 500 mL = 0.5 L
• 0.25 M = mol = 0.5 L x 0.25 M = mol 0.5 L
= 0.125 mol NaCl
Example 5• How many grams of NaCl are in 500 mL of a 2.25 M solution? • Basic formula: M = mol L • Convert: 500 mL = 0.5 L
• 2.25 M = mol = 0.5 L x 2.25 M = mol 0.5 L = 1.125 mol NaCl • 1.125 mol NaCl | 58.44 g NaCl = 65.75 g NaCl 1 mol