Analyze a situation involving the dilution of a solution in order to relate the number of moles, the volume and the molarity of the initial and the diluted solution. Most problems are scaffolded.
REVIEW: Which one of the following expressions can be used to determine the number of moles of solute in a solution if the volume (in Liters) and the molarity of the solution are known?
Jill Lushian is doing a chemistry lab. She has a 50.0-mL sample of iron(II) chloride with a concentration of 0.882 M.
How many moles of iron(II) chloride are in this solution?
Moles of FeCl3
mol
Jill then adds 400.0 mL of water to this solution until its final volume is 450.0 mL How many moles of iron(II) chloride are now in this solution?
What is the molarity of the iron(II) chloride in this final solution?
Final Molarity
M
Mrs. Mandochino dissolves 8.43 grams of copper(II) nitrate – Cu(NO3)2 - in 250.0 mL of aqueous solution.
What is the molarity of the solution?
Molarity
She then draws 50.0 mL of the solution into a pipet. How many moles of copper(II) nitrate are in the pipet?
Moles of Cu(NO3)2
Mrs. Mandochino empties the 50.0 mL into an empty volumetric flask and fills it to the 400.0 mL mark with distilled water. What is the molarity of this new solution?
Anna Litical obtains 0.200 L of a 0.828 M NaCl(aq) stock solution. This volume is then diluted with distilled water to a final volume of 1.600 L.
How many moles of NaCl are in 0.200 L of the stock solution?
Moles of NaCl
How many moles of NaCl are in the final solution?
What is the molar concentration of the final 1.600-L solution?
On Day 1 of a multi-day lab, lab partners Ray Ahn and Polly Ester prepare a 1.31 M aqueous solution of NaOH. On Day 2, Ray and Polly take 20.0 mL of this stock solution and dilute it with water in a 120.0-mL volumetric flask.
How many moles of NaOH did Ray and Polly withdraw from the stock solution?
Moles of NaOH
What is the final molar concentration of this Day 2 solution?
Jesus is Mr. Lebrum’s lab assistant. Jesus is preparing an aqueous solution of sodium chloride for a chemistry lab by diluting a standard solution of sodium chloride. Determine the volume of the 2.000 M NaCl solution that Jesus must use in order to make 2.586 L of 0.208 M NaCl solution.
Volume
L