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Arrhenius and CALCULATIONS December log 10 10 8 , 2.009 * 10 3

Arrhenius and CALCULATIONS December log 10 10 8 , 2.009 * 10 3. Objective: SWBAT calculate pH and pOH using known concentrations Catalyst: Which is a stronger acid, one with a pH of 5 or one with a pH of 3? Which is a stronger base, one with a pH of 11 or one with a pH of 14?

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Arrhenius and CALCULATIONS December log 10 10 8 , 2.009 * 10 3

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  1. Arrhenius and CALCULATIONSDecember log10108, 2.009 * 103 • Objective: • SWBAT calculate pH and pOH using known concentrations • Catalyst: • Which is a stronger acid, one with a pH of 5 or one with a pH of 3? • Which is a stronger base, one with a pH of 11 or one with a pH of 14? • Which is a stronger acid, one with a pH of 9 or one with a pH of 10?

  2. Agenda • Catalyst • What’s a pirate’s favorite model of acid and bases? • ARR-Henius! • Now, calc it out, calc it out, calc it out. • Reference sheet! • Practice • Exit Question

  3. Arrhenius Model for Acids and Bases • Key Point #1: • Arrhenius said: • Acids will dissociate (separate) to produce hydrogen ions • Bases will dissociate (separate) to produce hydroxide ions • An Arrhenius acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution HCl  H+ + Cl- • A Arrhenius base is a substance that contains hydrogen and ionizes to produce hydroxide ions in aqueous solution NaOH  Na+ + OH- This is called DISSOCIATION!

  4. Practiccce…. Are these Arrhenius acids or bases? • HCl • Mg(OH)2 • H2SO4 • Ca(OH)2 • HNO3 • NaOH • H2CO3 • NH4OH

  5. Concentration! • Now, we talked yesterday about how pH measures how STRONG or WEAK an acid or a base is. • What do you think would make an acid STRONGER? • More H+ or less H+ • What do you think would happen to the pH? • IT WOULD DECREASE!

  6. Concentration! • Now, we talked yesterday about how pH measures how STRONG or WEAK an acid or a base is. • What do you think would make an base STRONGER? • More OH- or less OH- • What do you think would happen to the pH? • IT WOULD INCREASE!

  7. How do we measure how much of something there is? • CONCENTRATION! • In chemistry terms, we call this MOLARITY. • Key Point #2: • Concentration is measured in molarity and is used to calculate pH and pOH.

  8. WHAAAAT THE HEEEECKK? • What’s pOH????!??!???! • Just like pH- which measures the Hydrogen ions, pOH measures the hydroxide ions. • pOH is just used less commonly… • With pOH… • Acids > 7 • Bases < 7

  9. Ready to calculate? • Your equations are on the blue sheet, but you need to know when to use the right ones… • Let’s practice this skill first.

  10. How do you pick equations? • Find the equation where the thing that you are looking for is BY ITSELF and the thing that you have is in the equation! • What is the pH of a solution with 3.2 * 10-3 M [H+]? • What is the [OH-] of a solution with a pOH of 12? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  11. Let’s practice • Logarithims are functions that deal with exponents. • Unfortunately, we do not have time to deal with all the funness of logs- Algebra 2 will though! • What is the [H+] of a solution that has a pH of 7? • [H+] = 10-pH EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  12. Let’s practice • What is the [H+] of a solution that has a pH of 9? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  13. Your turn • What is the [OH-] of a solution with a pOH of 12? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  14. Let’s practice • What’s the pOH of a solution with pH of 3? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  15. Let’s practice • What’s the pH of a solution with a pOH of 6? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  16. Your turn • What’s the pH of a solution that has 4.1 * 10-3 M [H+]? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  17. Your turn • What’s the pH of a solution that has 1.0 * 10-5 M [H+]? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  18. Your turn • What’s the pOH of a solution that has 3.4 * 10-3 M [OH-]? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  19. Your turn • What’s the pOH of a solution that has 1.7 * 10-4 M [OH-]? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  20. Tricksters… • What’s the pOH of a solution that has an [H+] of 1.3 * 10-3 M? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  21. Tricksters… • What’s the pH of a solution that has an [OH-] of 2.2 * 10-6 M? EQUATIONS! pH= -log [H+] [H+] = 10-pH pOH= -log [OH-] [OH-]= 10-pOH pH+pOH=14

  22. This is your time to shine… • Figure out those last problems!

  23. Exit Question • If a solution has a [H+] of .01, what is the pH of that solution? • What is the pOH of that solution?

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