today… before class: grab a lab packet, safety goggles, and apron our plan: inquiry lab wrap up...
TRANSCRIPT
Today… Before Class:
Grab a Lab Packet, Safety Goggles, and Apron Our Plan:
Inquiry LabWrap Up – Venn Diagram
Homework (Write in Planner): Inquiry Lab Due next class
Quiz Make Up Tomorrow ELORocket Lab Make Up Thursday ELO
Today… Turn in:
Acid/Base Lab if haven’t yet Grab YOUR LAST Calendar, Booklet, & WS Packet You need a TEXTBOOK today!
Our Plan: New Calendar Notes Stop the Process/Activity Notes – pH Worksheet #1
Homework (Write in Planner): Worksheet #1 Due next class
Chemistry Humor….
Properties of Acids & Bases
ACIDS BASES
Produce H3O+1 ions when dissolved in water
Produce OH-1 ions when dissolved in water
Properties of Acids & Bases
ACIDS BASES
Taste tart or sour
Taste Bitter
Properties of Acids & Bases
ACIDS BASES
Corrosive to body tissue
Feel Slippery
Properties of Acids & Bases
ACIDS BASES
Turn blue litmus red
Turn red litmus blue
Properties of Acids & Bases
ACIDS BASES
Metals react with acids to form hydrogen gas
Properties of Acids & Bases
ACIDS BASES
Electrolytes
Properties of Acids & Bases
ACIDS BASESChange
color of
indicator
Properties of Acids & Bases
ACIDS BASESReact together to
form water
& a salt
Nomenclature of Acids
HCl Hydrochloric Acid
HF Hydrofluoric Acid
HBr Hydrobromic Acid
HI Hydroiodic Acid
More Acids
HC2H3O2 Acetic Acid
H2SO4 Sulfuric Acid
HNO3 Nitric Acid
H2CO3 Carbonic Acid
H3PO4Phosphoric Acid
Nomenclature of Bases
Generally, bases are metal hydroxides, so name the metal + hydroxide
Examples:KOH – potassium hydroxideNaOH – sodium hydroxideLiOH – lithium hydroxide
Real Life Acids
VinegarAspirinVitamin C (orange juice)Soft Drinks (Coca Cola)Foods – Citrus Fruits,
Tomatoes
Real Life Acids
Stomach Acid (Bulimia)FertilizerCar Batteries Acne Face Washes
Real Life Bases
AntacidsDeodorantsPlasterLaxativesBaking Soda
Real Life Bases
Dish DetergentBody Wash (Soap)LyeOven & Drain CleanerBleach
STOP
Complete the Stop the Process Activity in your notes.
Strong Acids/Bases
Fight Club Videohttp://www.youtube.com/watch?v=mg3m
8wRVXWg
Hydrogen Ions in Water
Water molecules, like anything, are in constant, random motion
Occasionally the collisions between water molecules are energetic enough to transfer a hydrogen ion from one molecule to another
Hydrogen Ions in Water
A water molecule that loses a hydrogen ion becomes a negatively charged hydroxide ion (OH-1)
A water molecule that gains a hydrogen ion becomes a positively charged hydronium ion (H3O+1)
Hydrogen Ions in Water
The reaction in which water molecules produce ions is called the self-ionization of water.
2H2O ↔ H3O+1 + OH-1
The Ionization of Water
2H2O ↔ H3O+1 + OH-1
At equilibrium, only 1.0 x 10-7 moles of H3O+1 and OH-1 are formed (at room temperature). So the concentrations of H3O+1 and OH-1 in pure water are 1.0 x 10-7 M.
The Ionization of Water
This means the concentrations of H3O+1 and OH-1 are equal in pure water.
Any aqueous solution in which [H3O+1] and [OH-1] are equal is called a neutral solution.
The Ionization of Water
In any aqueous solution, the product of hydronium ions and hydroxide ions equals 1 x 10-14
[H3O+1] [OH-1] = Kw = 1 X 10-14
Brackets indicate concentrationKw represents the ion-product
constant of water
Acidic & Basic Solutions
Not all solutions are neutralIf the concentration of hydronium is
greater than hydroxide, the solution is ACIDIC
If the concentration of hydronium is less than hydroxide, the solution is BASIC (alkaline)
pH
The concentrations of [H3O+1] & [OH-1] can be very small, and expressing concentration in molarity can be a pain, so…
Soren Sorensen came up with the pH scale in 1909
The pH scale is from 0-14, 0 being very acidic and 14 being very basic
pH
French for pouvoir hydrogene, which means “hydrogen power”
Low pH = very acidicHigh pH = very basic 7 = Neutral
Calculating pH
To turn such small concentrations into a pH scale, it is necessary to use logarithms
Logarithms allow a large range of values to be conveniently expressed as small, nonexponential numbers.
Do you remember logarithms from math class?
Calculating pH
For example, log 103 = 3 and log 106 = 6. Although there is a range of three orders of magnitude (10 x 10 x 10 or 1000) between the numbers 103 and 106, the range of the log values is only 3!
Calculating pH (strong acids)
To calculate, use:pH = -log[H3O+1]
[H3O+1] = hydronium ion concentration
WHY?
This is because strong acids completely dissociate
This means that the molarity of the acid IS THE SAME AS the molarity of H3O+1
Neutral Water
For this reason, neutral water has a pH of 7!
pH = -log[1 x 10-7]pH = 7Try typing it in your calculator
Try it Out!
Complete the pH table in your Note Booklet using your calculator and the formula.
The Answers
pH 10-pH
0 1
1 0.1
2 0.01
3 0.001
4 0.0001
The Answers
pH 10-pH
5 0.00001
6 0.000001
7 0.0000001
8 0.00000001
9 0.000000001
The Answers
pH 10-pH
10 1 x 10-10
11 1 x 10-11
12 1 x 10-12
13 1 x 10-13
14 1 x 10-14
pH
The numbers in the column 10-pH that you found are the hydronium ion concentration
To calculate [H3O+1] = 10-pH
pOH
pOH is the same as pH, but instead of being a measure of the hydronium ion concentration, it is the measure of the hydroxide ion concentration
It is the exact opposite!
pOH
Low pOH = very basic (alkaline)
High pOH = very acidic7 = neutral
Calculating pH (strong acids)
To calculate, use:pOH = -log[OH-1][OH-1] = hydroxide ion concentration
WHY?
This is because strong bases completely dissociate
This means that the molarity of the base IS THE SAME AS the molarity of OH-1
pOH
To calculate [OH-1]: [OH-1] = 10-pOH
Combining pH and pOH
pH +pOH = 14
The Flow Chart
What is the pH if the [OH-1]is 3.8 x 10-4 M?
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Example
What is the pOH if the [H3O+1] is 6.2 x 10-1 M?
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Example
What is the [H3O+1] if the [OH-1] is 1.3 x 10-8 M?
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Try It Out
What is the pH if the [OH-1] is 3.80 x 10-4 M?
10.6
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Try It Out
What is the pOH if the [OH-1] is 6.8 x 10-
6 M?
5.2
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
STOP…Worksheet Time!
Complete Worksheet #1 for next class.
Wrap Up
Properties of Acids & Bases Review
Today… Turn in:
WS #1 & Get out NOTES & CALCULATOR Our Plan:
Review Activities (Properties, Conjugate Acid/Base, pH calculations)
Homework Help Quiz – pH calculations Notes Worksheet #2 Wrap Up – Go Fish
Homework (Write in Planner): Worksheet #2 Due next class
Review
Properties of Acids & Bases Review
Conjugate Acid/Base ActivityExample H3PO4
Homework Help
10 Green A solution of
strontium hydroxide with a pH of 11.4 is to be prepared. What mass of strontium hydroxide would be required to make 1.00 L of this solution?
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Homework Help
11Green/11 Yellow Calculate the pH of
a solution that contains 5.00 g of HNO3 in 2.00 L of solution.
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Homework Help
12 Green/9 Yellow A hydrochloric acid
solution has a pH of 1.70. What is the [H3O+1] in this solution? Considering that HCl is a strong acid, what is the HCl concentration of the solution.
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Homework Help
13 Green/10 Yellow What is the molarity
of a solution of the strong base Ca(OH)2 in a solution that has a pH of 10.80?
- log[H3O+1]
[H3O+1] [OH-1]
10-pOH
pH pOH
- log[OH-1]
10-pH
pH + pOH = 14
Your Turn to Review
Complete the table of pH values individually. Check your work with your neighbor. After completing the review, you will take a quiz that looks exactly the same with different numbers!
Review Answers
[H3O+1] pH pOH [OH-1]
0.079 M 1.1 13 1.3 x 10-13 M
4.0 x 10-8 M 7.4 6.6 2.6 x 10-7 M
2.0 x 10-5 M 4.7 9.3 5.0 x 10-10 M
3.5 x 10-3 M 2.5 12 1.0 x 10-12 M
pH of Weak Acids
We calculate the pH of weak acids differently because they partially dissociate
That means the concentration of the acid IS NOT the same as the [H3O+1]
pH of Weak Acids
We use something called the Ka (the acid ionization constant)
It has been determined by experiments and is different for each acid
Determining Ka
Ka = [Products]
[Reactants]
How the pH formula is derived
What is the pH of a solution of 0.1 M acetic acid if the Ka for acetic acid is 1.8 x 10-5?
CH3COOH + H2O↔ CH3COO-1 + H3O+1
0.1 M XXn/a
How the pH formula is derived
Ka = [Products] [Reactants]1.8x10-5= __x2___ 0.1Mx is the [H30+1], which is
what we need to find pH!
How the pH formula is derived
CH3COOH + H2O↔ CH3COO-1 + H3O+1
0.1 M n/a X X
(0.1M)1.8*10-5= x2 (0.1M)
0.1M
√ 1.8*10-6= √x2
1.3 x 10-3= x = [H3O+1]
How the pH formula is derived
Basically, we multiplied the Ka by the concentration of the acid and took the square root of it.
Thus, the equation:
Equation for pH weak acids
[H3O+1] = √ Ka [HA]
Once you find [H3O+1], solve for pH just like before!
Sample Problem
Find the pH of a 0.4 M acetic acid solution. Ka for acetic acid is 1.8 x 10-5.
Sample Problem
[H3O+1] = √ (0.4M)(1.8 x 10-5)
[H3O+1] = 0.00268
pH = -log [H3O+1]
pH = -log[0.00268]pH = 2.57
Try It Out!
Find the pOH of a 0.33M acetic acid solution. Ka for acetic acid is 1.8 x 10-5.
Try It Out!
[H3O+1] = √ (0.33M)(1.8 x 10-5)
[H3O+1] = 0.00243
pH = -log [H3O+1]
pH = -log[0.00243]pH = 2.61
Not Done Yet!
pH + pOH = 1414 – 2.61 = pOHpOH = 11.39
Let’s do a hard one from the WS
#4 on BOTHWhat is the concentration of citric acid if
the solution has a pH of 2.5? (0.012 M)
pH Practice Problems
Complete WS # 2 by next class!
Wrap Up
Go Fish Time!
Today… Turn in:
WS #2 Our Plan:
ReviewQuizNotes/Videos IndicatorMake SherbetGo Fish
Homework (Write in Planner):Nothing
Review
1. What is the [OH-1] of a 0.4 M strong acid solution? 2.5 x 10-14
2. What is the pOH of a 6 x 10-4 M solution of strong base? 3.22
3. What is the pH if the pOH is 2.9? 11.1
4. What is the pOH of a 0.8 M weak acid solution of acetic acid. Ka for acetic acid 1.8 x 10-5 M. 11.57
Acid – Base Demonstration
Acid – Base Demonstration
IndicatorsDefinition: Compounds
whose colors are sensitive to pH
Their color
changes as pH
changes
Indicators
Transition interval – the pH range over which an indicator changes color
Examples: phenolphthalein, methyl red, bromthymol blue….
Sherbet Activity
Make an acid/base reaction in your mouth to create the flavor of sherbet.
In a small paper cup combine the following ingredients: 1/2 teaspoon of citric acid crystals 1 teaspoon of icing sugar 1/2 teaspoon of drink crystals 1/4 teaspoon of sodium bicarbonate (baking soda = base)
Mix the ingredients with a popsicle stick. Enjoy the sherbet (but not all at once). It foams in
your mouth!
Wrap Up
Go Fish Time!
Today…Turn in:
NothingOur Plan:
Slap Jack NamesIndicator LabWrap Up – Spoons & Slap Jack
Homework (Write in Planner):Indicator Lab Today
LAB TIME!
Test every item with all of the indicators to determine the pH by placing 10 drops of the item to be tested in each test tube and adding 2 drops of the indicator. Then use the provided charts to determine the pH. The group that gets closest to the actual pHs will get 10 EXTRA CREDIT POINTS! If a member of your group has an electronic device out you are disqualified!
The Correct Answers
Item Actual pH7-UP 3.40
Vinegar 1.20
Fruit Juice 3.86
Lime Water 2.45
Tap Water 6.90
Soapy Water 3.61
Ammonia 12.01
Sour Candy 3.07
Crushed Aspirin 3.00
Today… Get Out:
Notes, WS Packet, Calculator Indicator Lab Make Up in ELO Today
Our Plan: Demo – Rainbow in the Blue Notes – Neutralization/Titrations Worksheet #3 Gizmo Standardize a Base Lab
Homework (Write in Planner): WS #3 Due Next Class
Rainbow Indicator Demos
http://www.youtube.com/watch?v=VMk37PX_bFI
http://www.youtube.com/watch?v=PdprNTwb4Ks
Polyprotic Acids
Acids such as H2SO4 , H3PO4 or H2CO3 that have more than one hydrogen (proton) to donate.
Polyprotic Acids
1 mole of H3PO4
Ionized…3 moles H+1 1 mole PO4
-3=
Neutralization
Occurs when equal molar amounts of acid and base are added.
In neutralization:Acid + Base --> Salt + Water
Neutralization Reaction
Example: HCl + NaOH NaCl + H2O
Neutralization
The number of moles of each substance needed depends on the ratio of H+1 to OH-1.
If it’s 1:1, the same amount of each is needed.
If there are 2 hydrogens to every 1 hydroxide, you would need twice as much base
Examples
_____ moles NaOH with 6.0 moles HCl
_____ moles H2SO4 with 4.0 moles KOH
6.0
2.0
Examples
_____ moles H2SO4 with 6.0 moles Al(OH)3
_____ moles H3PO4 with 15.0 moles LiOH
9.0
5.0
Neutralization
Neutralization & Titrations
Definitions:Titration: The process in which a
standard solution is added to a solution of unknown concentration to determine its concentration.
End Point: The point in a titration when the indicator changes color.
Titrations What is needed for a titration?
1. A solution whose concentration is known = Standard Solution
2. An accurate way to measure the volume of that solution = Buret
3. A way to determine when the reaction is complete = Indicator
Titration
What is a titration?
Buret filled with standard solution
Flask filled with solution of unknown concentration
Titration Video
TitrationsAcid Base Titrations are
reactions between strong acids and strong bases.
H+1 + OH-1 H2O
By doing a titration, you can calculate how many moles of acid and base there are.
Titrations
If the amount of either H+1 or OH-1 are known, the amount of the other can be calculated. (1:1 Ratio)
Titrations
To Calculate: Remember Molarity?
M = moles
LConcentration of solution
Moles of solution
Volume of solution
Titrations
Remember Dilutions?
MAVA = MBVB
Concentration of Standard Acid Solution
Volume of Standard Solution
Concentration of Unknown Base Solution
Volume of Unknown Solution
Example
After titrating, you found that 50 mL of 0.1 M HCl was neutralized by 29 mL of NaOH. What was the Molarity of the base?
Example
MAVA = MBVB
Use Algebra to solve for x!x = 0.17 M
50 mL0.1 M X 29 mL
Example 2
After titrating, you found that 48 mL of 0.5 M NaOH was used to neutralize 25 mL of HCl. How many moles of HCl are in the flask, AND what is its concentration?
Example
MAVA = MBVB
Use Algebra to solve for x!x = 0.96 M
25 mLx 0.5 M 48 mL
Example Continued
Now find the number of moles…
M = moles
L0.96 M
X
0.025 Lx = 0.024 moles
Try It Out!
After titrating, you found that 53 mL of 0.05 M NaOH was used to neutralize 36 mL of HCl. What was the concentration of the HCl?
Try It Out!
MAVA = MBVB
Use Algebra to solve for x!x = 0.074 M
36 mLx 0.05 M 53 mL
CONGRATULATIONS!
YOU HAVE COMPLETED ALL OF THE CURRICULUM FOR GENERAL CHEMISTRY!
Homework Time!
Complete WS #3 by next class!
Gizmo
If you have never logged in to Gizmos before use the code:AE462EHSKZAE38GSQZ5VAE53MQIMSVAE5YGBAF8Z
Wrap Up
What 3 things do you need for a titration?
Today… Turn in:
WS#3 Our Plan:
Review Quiz WS#3 Work Day
Missing Assignments/Labs/Quizzes Test Review
Bluff Homework (Write in Planner):
Test Review Due Next Class TEST NEXT CLASS!
Review Problem
Complete the Worksheet #3 Review Problem on p. 19 of your notes.
Today… Turn in:
Test Review to Check Our Plan:
Station ReviewTest Review QuestionsTestWork Quietly/Start Final Study Guide
Homework (Write in Planner):Nothing
Today… Turn in:
Goal Sheet Our Plan:
Antacid Lab TestWork on Final Test ReviewWrap Up – Present your findings to the
class Homework (Write in Planner):
Nothing
Today…Turn in:
Antacid LabOur Plan:
Final Test Review (30 points)Prepare Your NotecardReview Board Game
Homework (Write in Planner):Test Review Due Next Class
Today…Turn in:
Final Test ReviewOur Plan:
Take the FinalPencil, Scratch Paper, PT, Notecard, Calculator
Relax/StudyHomework (Write in Planner):
Have a Great Summer! Come back and visit me! I’ll miss you!