1 / 27

Strong vs Weak Acids 4-28-14

Strong vs Weak Acids 4-28-14. Strong acids ionize completely. HCl  H + + Cl - HNO 3  H + + NO 3 - H 2 SO 4  2H + + SO 4 -. Weak Acids ionize partially. H 2 CO 3  2H + + CO 3 - CH 3 COOH  H + + CH 3 COO - H 3 PO 4  3H + + PO 4 -.

amal
Download Presentation

Strong vs Weak Acids 4-28-14

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. Strong vs Weak Acids 4-28-14

  2. Strong acids ionize completely HCl H+ + Cl- HNO3  H+ + NO3- H2SO4  2H+ + SO4-

  3. Weak Acids ionize partially H2CO3 2H+ + CO3- CH3COOH  H+ + CH3COO- H3PO4  3H+ + PO4-

  4. Ka is the acid dissociation constant • Large Ka value means more ionization, means stronger acid. • Smaller ka value means less ionization, means weaker acid.

  5. 1.Which acid is stronger? • Methanoic acid ka= 1.8 x 10-4 • Carbonic acid ka= 4.3 x 10-7

  6. 2.Which acid is weaker? • Ethanoic acid ka = 1.8 x 10-3 • Oxalic acid ka = 5.6 x 10-2

  7. https://www.youtube.com/watch?v=kdEh976I1YA

  8. Neutralization Reactions When an acid reacts with a base, the product is always a SALT and WATER. HCl + NaOH NaCl + H2O HNO3 + KOH  KNO3 + H2O CH3COOH + NaOH  NaCH3COO + H2O

  9. Write the reaction ratio under the equation Example: HCl + NaOH NaCl + H2O 1 mol 1 mol 1 mol 1 mol

  10. Your turn 3. H2SO4+ 2NaOH  Na2SO4 + 2 H2O 4. 2HCl + Ca(OH)2  CaCl2 + 2 H2O

  11. Titration • to find concentration of an unknown acid or base • Use the balanced equation to set up a mole ratio • Use the volume of titrant to calculate concentration of unknown

  12. Titration: strong acid with strong base

  13. Titrating weak acid with strong base

  14. Comparing strong acid vs weak acid titration with strong base

  15. How does a titration work? 1. A measured volume of an acid solution of unknown concentration is added to a flask 2. Several drops of indicator are added to the solution while the flask is gently swirled 3. Measured volumes of a base of known concentration (standard solution) are added until the indicator just barely changes color. 4. Neutralization occurs at the equivalence point = end point of the titration (color change)

  16. Calculations A 25ml of H2SO4 is neutralized by 18ml of 1.0M NaOH. What is the concentration of the H2SO4 solution? H2 SO4 + 2 NaOH Na2 SO4 + 2H2O Known: Stoich: Final equation: Molarity = mol / L

  17. https://www.youtube.com/watch?v=SBHGaY3kA4U

  18. How to • Convert ml to L (divide by 1000) • Find moles of base (moles = M x L) • Use balanced equation to set up mole ratio (place unknown at the top) • Multiply answer from 2. (moles) with the ratio from 3. (mole ratio) • Find concentration of acid M =moles L (answer of 4. divided by L of acid from 1.)

  19. Practice A 50 ml of H2SO4 is neutralized by 25ml of 1.0M NaOH. What is the concentration of the H2SO4 solution? H2 SO4 + 2 NaOH Na2 SO4 + 2H2O

  20. Practice/exit slip A 25ml of H2SO4 is neutralized by 50ml of 1.0M NaOH. What is the concentration of the H2SO4 solution? H2 SO4 + 2 NaOH Na2 SO4 + 2H2O

  21. Bellwork 25ml of HCl are titrated with 30 ml of 0.5M NaOH. What is the concentration of the acid. HCl + NaOH NaCl + H2O

  22. Work due by end of class today: Lab report with completed calculations Vocab foldable

  23. Put on your goggles andSet up your burettesTitration strong acid with strong base • Fill burette with NaOH solution. Record your starting volume . • Measure 20 ml of HCl into a small Erlenmeyer flask (using a measuring cylinder) • Add 5 drops of Bromothymol blue indicator. • Swirl flask gently as you add NaOH from the burette to the flask until you get a slight color change to green/blue • Record volume used from the burette Work in groups of 3

  24. Average

  25. Calculate the molarity (M) of the acid (HCl) HCl + NaOH NaCl + H2O ___ml ____ml ? M 0.1M

  26. Vocab foldable (grade for color/quality/completeness) Equivalence point End point Titration Weak acid Strong acid Base Alkaline Buffer Indicator Phenolphtalein Bromothymol blue Neutralization Molarity Standard solution

More Related