1 / 22

Normality

Normality. Dr. Steve Badger. Number of moles of solute. Molarity =. Liter of solution. Number of moles of solute. Molality =. Kg of solvent. Concentrations of Solutions. A brief review of molarity & molality. Preparing a Solution of Known Molarity.

darva
Download Presentation

Normality

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. Normality Dr. Steve Badger

  2. Number of moles of solute Molarity = Liter of solution Number of moles of solute Molality = Kg of solvent Concentrations of Solutions A brief review of molarity & molality

  3. Preparing a Solution of Known Molarity

  4. Would you use a volumetric flask to prepare a solution of known molality? How would you prepare a solution of known molality?

  5. Number of moles of solute Molarity = Liter of solution Number of equivalents of solute Normality = Liter of solution Another way to express solution concentration • Now that you understand molarity… …let’s consider normality!

  6. What’s an equivalent ? • An equivalent of a substance is the mass (grams) of that substance that will combine with one mole of another reactant. • In an acid-base reaction, an equivalent is that amount of a substance that reacts with or liberates 1.0 mole of H+.

  7. What’s an equivalent ? • An equivalent of a substance is the mass (grams) of that substance that will combine with one mole of another reactant. • In a redox reaction, an equivalent is that amount of a substance that gains or loses 1.0 mole of e–s.

  8. Making a 1.00N Solution • Calculate the mass of one equivalent of the substance, then measure that number of grams of the substance. • Put that substance in…. ?? • Add how much solvent?

  9. Preparing a Solution of Known Normality

  10. AbNormality? • Why don’t many modern chemistry textbooks cover normality? • If we take a dimensional analysis approach to problems solving, normality is a superfluous concept. • Consider the following problem:

  11. H2SO4 + KOH H2O + K2SO4 What volume of a 0.500 M KOH solution is required to titrate 10.0 mL of a 0.20 M H2SO4 solution? Could we just use this equation? MaVa = MbVb

  12. Here’s what we’d get if we used MaVa = MbVb 0.20 M H2SO4X 10.0 mL = 0.500 M KOH X ? mL Solving this, we get 4.0 mL of0.500 M KOH. But is this correct? No, it’s wrong! Why? So let’s see how we solve this correctly.

  13. H2SO4 + KOH H2O + K2SO4 M M rx volume acid moles acid moles base volume base base acid coef. What volume of a 0.500 M KOH solution is required to titrate 10.0 mL of a 0.20 M H2SO4 solution? BALANCE THE CHEMICAL EQUATION!

  14. H2SO4 + 2KOH 2H2O + K2SO4 M M rx volume acid moles acid moles base volume base base acid coef. ___ mol H2SO4 __ mol KOH ____ ml soln x x x ____ mL soln __ mol H2SO4 ____ mol KOH What volume of a 0.500 M KOH solution is required to titrate 10.0 mL of a 0.20 M H2SO4 solution? 10.0 mL = ___ mL

  15. M M rx volume acid moles acid moles base volume base base acid coef. 0.20 mol H2SO4 2 mol KOH 1000 ml soln x x x 1000 mL soln 1 mol H2SO4 0.500 mol KOH What volume of a 0.500 M KOH solution is required to titrate 10.00 mL of a 0.20 M H2SO4 solution? H2SO4 + 2KOH 2H2O + K2SO4 10.0 mL = 8.0 mL

  16. M M rx volume acid moles acid moles base volume base base acid coef. 0.20 mol H2SO4 2 mol KOH 1000 ml soln x x x 1000 mL soln 1 mol H2SO4 0.500 mol KOH Notice this! 10.0 mL = 8.0 mL Notice this! This is what makes normality superfluous!

  17. Is the following statement true or false? • Any volume of a base will completely react with (neutralize) that same volume of acid if the two solutions have the same normality (vice versa too). • In other words, is this true: NaVa = NbVb

  18. Is the following statement true or false? • Any volume of a reducing agent will completely react with that same volume of an oxidizing agent if the two solutions have the same normality. • In other words, is this true: NoxVox = NredVred

  19. Let’s solve a few problems using normality • Look at the handout that has sample problems and work the first one.

  20. And another thing… • We also use equivalents and milliequivalents as an amount of a substance • The same way that we use moles (mol) and millimoles (mmol) as an amount of a substance

  21. If you need more help: Come by my office and I can give you a few pages of worked examples from a Schaum’s Solved Problems Series. You can download this PowerPoint file at my EU web site: www.evangel.edu/Personal/badgers/Web/

  22. The End Now wasn’t that fascinating?

More Related