1 / 18

Formulate an operational definition of pH Solve problems involving pH

Formulate an operational definition of pH Solve problems involving pH Describe how an acid-base indicator works in terms of colour shifts and Le Chatelier’s Principle. Additional KEY Terms. Acidic: [H 3 O + ] > [OH - ] Alkaline (basic): [OH - ] > [H 3 O + ]

kasa
Download Presentation

Formulate an operational definition of pH Solve problems involving pH

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. Formulate an operational definition of pH • Solve problems involving pH • Describe how an acid-base indicator works in terms of colour shifts and Le Chatelier’s Principle Additional KEY Terms

  2. Acidic: [H3O+] > [OH-] Alkaline (basic): [OH-] > [H3O+] Neutral: [OH-] = [H3O+] 1909 - Soren Sorensen developed a simplified system for the degree of acidity of a solution. pH - the potenz (power) of hydrogen - German potentia hydrogenii - Latin

  3. Convenient and simple way to express [H+] • Equation 1: pH = - log [H+] • Equation 2: [H3O+] = 10-pH pOH has its own scale – like pH – that runs from 0-14 for strength of bases. Equation 3:pOH = - log [OH-] Equation 4: [OH-] = 10-pOH

  4. In a neutral solution pH & pOH = 7 Acidic - pH < 7 Basic - pH > 7 Equation 5:pH+pOH = 14

  5. Calculate the pH of an HCl solution whose concentration is 5.0 x 10-6 mol/L. remember strong acids are 100% dissociating: [HA]i = [H+]e = [A-]e pH = -log[H+] = -log(5.0 x 10-6 M) = -(-5.30) = 5.30

  6. The pH of a solution is 3.25. Calculate the hydrogen ion concentration in the solution. [H3O+] = 10-pH Find the “10 x” button on your calculator. = 10-3.25 = 5.6 x 10-4 M

  7. The pH of a solution is 10.30, what is the hydroxide ion concentration? OR solved this way pOH = 14.00 - pH pOH = 14.00 - 10.30 = 3.70 [H+] = 10-pH [OH-] = KW [H+] [OH-] = 10-pOH = 10-3.70 = 2.0 x 10-4 mol/L

  8. Mg(OH)2 (s) Mg2+(aq) + 2 OH-(aq) xi xf 2xf What is the pH of 5.0 x 10-5 M Mg(OH)2 solution? remember strong bases are 100% dissociating x 0 0 [I] [C] - x + x + 2x x 2x 0 [E] [OH-] = 2x = 2(5.0 x 10-5 M) = 1.0 x 10-4 M pOH = -log[OH-] = 4.00 pH = 14.00 - 4.00 = 10.00

  9. YOUR ACID/BASE FORMULAE: • Kw = [H+][OH-] = 1.0 x 10-14 • The pH and pOH scales goes from 0 - 14. • pH = -log[H+] and[H+] = 10-pH • pOH = -log[OH-] and[OH-] = 10-pOH • pOH + pH =14

  10. Measuring pH There are two ways to measure pH: pH Meters Indicators The [H+] inside the probe (reference electrode) is compared to [H+] outside the probe. Probe must be calibrated first. (inserted into known pH solution)

  11. Indicator: a weak acid or base that undergoes a colourchange when they gain or lose hydrogen ions. • Colour change occurs at various pH depending on indicator • Le Chatelier’s applies to the colour change Natural pH indicators Beets, Blackcurrant juice, Blueberries , Carrots , Cherries , Curry Powder , Grapes , Onion , Petunia Petals , Poison Primrose , Poppy Petals , Red cabbage , Red Radish , Rhubarb , Rose Petals , Strawberries ,Tea , Thyme , Turmeric , Tulip Petals , Violet Petals

  12. Red Litmus stays red in the presence of an acid.

  13. It turns blue in presense of a base.

  14. Phenolphthaleinis a commonly used indicator. • Weak acid is colourless and its conjugate base ion is bright pink

  15. CAN YOU / HAVE YOU? • Formulate an operational definition of pH • Solve problems involving pH • Describe how an acid-base indicator works in terms of colour shifts and Le Chatelier’s Principle Additional KEY Terms

More Related