1 / 15

Units of Concentration

Units of Concentration. A solution is a homogeneous mixture of one substance (the solute) dissolved in another substance (the solvent). Concentration is a ratio of the amount of solute to the amount of solvent. Units of Concentration. Percent volume

derossett
Télécharger la présentation

Units of Concentration

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. Units of Concentration • A solution is a homogeneous mixture of one substance (the solute) dissolved in another substance (the solvent). • Concentration is a ratio of the amount of solute to the amount of solvent.

  2. Units of Concentration • Percent volume % volume = volume solute (ml) x 100 volume solution (ml) • Percent mass % mass = mass solute (g) x 100 mass solution (g) Solution = solvent + solute

  3. Units of Concentration Example 1: What is the percent by volume concentration of a solution in which 75.0 ml of ethanol is diluted to a volume of 250.0 ml? 75.0 ml x 100 = 30.0% 250.0 ml

  4. Units of Concentration Example 2: What volume of acetic acid is present in a bottle containing 350.0 ml of a solution which measures 5.00% concentration? x = 0.05 350.0 ml x = 17.5 ml

  5. Units of Concentration Example 3: Find the percent by mass in which 41.0 g of NaCl is dissolved in 331 grams of water. 41 g x 100 = 11.0% 372 g

  6. Units of Concentration • Molarity (M) is the most common unit of concentration • Molarity is an expression of moles/Liter of the solute.

  7. Units of Concentration • A mole is the SI unit of number of particles and can be used as an expression of the molecular weight of a substance. The formula weight of an element is expressed as grams/mole

  8. Units of Concentration • The molar mass of a compound can be calculated by adding the molar mass of the individual elements. 22.99 + 35.45 = 58.44 g/mol

  9. Making Solutions • You just calculated the molar mass of sodium chloride to be 58.44 g/mol. • To determine how to make a stock solution of sodium chloride, use the formula: g = M x L x molar mass

  10. Making Solutions • How many grams of NaCl would you need to prepare 200.0 mL of a 5 M solution? g = M x L x molar mass g = (5mol/L) (0.2L) (58.44g/mol) g = 58.44 g

  11. Diluting Solutions • Often once you have made a stock solution, you need to dilute it to a working concentration. • To determine how to dilute the stock solution, use the formula: C1 – concentration of stock C2 - concentration of diluted solution V1 – volume needed of stock V2 – final volume of dilution C1V1 = C2V2

  12. Diluting Solutions Example 5: How many milliliters of a 5 M stock solution of NaCl are needed to prepare 100 ml of a 0.4 M solution? C1 V1 = C2 V2 (5) V1 = (0.4)(100) V1= 8 ml

  13. Diluting Solutions • Serial Dilutions are dilutions made in series (for example, if you needed to make solutions that were 2M, 1M, 0.5M, and 0.25 M) • The formula for serial dilutions is: Dilution Factor = (V1 +V2) V1 V1 – volume of solution being diluted V2 – volume of solvent

  14. Units of Concentration Example 6: Propose a method to prepare 100 ml of a 0.5 M glucose solution from a 5 M glucose solution. 10 = (v1 + 100) v1 10v1 = v1 + 100 -v1 -v1 9v1 = 100 9 9 v1 = 11.1 ml of 5 M glucose + 100 ml H2O

  15. Diluting Solutions Dilutions tutorial

More Related