1 / 5

Understanding Molarity: Calculating and Preparing Solutions

Molarity is a key unit of concentration for chemists, defined as moles of solute per liter of solution. To calculate molarity, consider the total volume of the solution, which includes both solute and solvent. For example, a saline solution with 0.90 g of NaCl in 100 mL corresponds to a molarity of 0.15 M. This guide covers problem-solving techniques in molarity, including conversions between grams and moles, and the preparation of solutions, like making a 0.25 M copper(II) chloride solution.

leola
Télécharger la présentation

Understanding Molarity: Calculating and Preparing Solutions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Molarity • Unit of Concentration • There are many units of concentration • Molarity is most useful to the chemist M = moles of solute Liters of solution Liters of solution means the total volume of water and solute. If I want a liter of solution I will not use a liter of water.

  2. Molarity ProblemsYou work them. • A saline solution contains 0.90 g NaCl in exactly 100 ml of solution. What is the molarity of the solution? • Convert g to moles • 0.90g NaCl 1 mol NaCl 58.5 g NaCl = 0.015 mol NaCl Take 0.015 moles/ .100 L • Answer - 0.15 mol/L or 0.15 M NaCl

  3. Molarity ProblemsYou work them. • How many moles of solute are present 1.5 L of 0.24 M Na2SO4? • 0.24 M = x mol solve for x • 1.5 L • Answer - 0.36 mol of Na2SO4 • What if I asked you to find how many grams of solute are present in the previous problem. • Convert your moles to grams.

  4. Preparing a solution • How would you make 500.0 ml a 0.25 M solution of copper (II) chloride? • 0.25 M = mol/0.5000 L - change ml to liters and solve for moles. • You need 0.13 moles of CuCl2. Converting to grams equals 17 grams. • Final answer • Take 17 grams of CuCl2 and dissolve in enough water to make 500.0 ml of solution. • Dissolve the 17 grams in say 400 ml of water. Once the CuCl2 is dissolved add water up to 500.0 ml.

  5. Preparing a solutionyour turn • How would you prepare a solution of 0.40 M KCl? If a volume is not given assume 1 L. • 0.40 M = mol/ 1 L mol = 0.40 mol needed • 0.40 mol 74.6 g KCl = 3.0x101 grams KCl 1 mol KCl Take 3.0x101 grams of KCl and dissolve in enough water to make a liter of solution.

More Related