arrhenius and calculations december log 10 10 8 , 2.009 * 10 3
Post on 01-Jan-2016
26 Views
Preview:
DESCRIPTION
TRANSCRIPT
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?
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
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!
Practiccce…. Are these Arrhenius acids or bases? HCl Mg(OH)2
H2SO4 Ca(OH)2
HNO3
NaOH H2CO3
NH4OH
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!
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!
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.
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
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.
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
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
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
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
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
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
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
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
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
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
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
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
This is your time to shine…
Figure out those last problems!
Exit Question
If a solution has a [H+] of .01, what is the pH of that solution?
What is the pOH of that solution?
top related