Re-teach week continued
Boon Chemistry January 10 and 11, 2013
Catalyst
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Write at least five
sentences answering any or
all of the following
questions:
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What is your favorite type of
environment for studying or
doing homework?
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Describe the place, time, noise
level, other surrounding
circumstances.
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Objectives
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I can calculate the concentration
of a solution.
I can describe the dissolving
process on the molecular level.
I can perform scientific notation
calculations.
Agenda
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Catalyst
Benchmark Redo Quiz
Scientific Notation Review
Acids and Bases Vocabulary
Benchmark Redo Quiz
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Expectations:
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Tools:
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You will work silently and independently.
When you are done, cover your quiz with your handouts.
You may use your concentration foldable and intermolecular
forces handout to help you.
You may use your own calculator.
What do I turn in?
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You will turn in your quiz, concentrations foldable, and
intermolecular forces handout.
Scientific Notation
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Our next unit is acids and bases and we will be working
with numbers in scientific notation.
Scientific notation is a shorthand way of expressing really
large numbers or very small numbers.
There are two rules to keep in mind when writing a
number in scientific notation.
2.5 x 105
The first number has to
be greater than or
equal to 1 and less than
10.
The second number is
10 to a power. The
power will show how
many places to move
the decimal point.
Scientific Notation Quick Check
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Thumbs up for proper scientific notation and thumbs
down for incorrect scientific notation.
4.0 x
-2
10
Scientific Notation Quick Check
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Thumbs up for proper scientific notation and thumbs
down for incorrect scientific notation.
15 x
8
10
Scientific Notation: Conversions
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To translate a number from scientific notation to standard
form, look at the exponent on the 10.
2.5 x 105
If the exponent is
positive move the
decimal to the right.
2.5 x 105 = 250,000
2.5 x 10-4
If the exponent is
negative move the
decimal to the left.
2.5 x 10-4 = 0.00025
Scientific Notation: Conversions
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To translate a number from standard notation to scientific
notation put the decimal after the first digit, keep all
other different digits, but drop the repeated zeros.
23,000
Determine the
exponent by counting
how many places you
have to move the
decimal point to get
back to your original
number.
2.3 x 10?
2.3 x 104
Scientific Notation: Addition
Addition: Example – A chemist mixes a solution by combining 3.0 x 102 mL
KOH to 5.0 x 103 mL water. What is the total volume of the solution in mL?
Step 1: In order to add, the exponents must be the same. Convert the first
quantity to a multiple of 103 to match the second quantity.
3.0 x 102 mL KOH = 0.30 x 103 mL KOH
because the exponent is increased by one, the decimal point moves one place
to the left.
Step 2: Add. Remember to line up the decimal points.
0.30 x 103 mL KOH
+ 5.0 x 103 mL water
Answer:
5.30 x 103 mL solution
Step 3: Convert to proper scientific notation!
The answer is already in the proper notation because 5.3 is between 1 and 10.
Scientific Notation: Subtraction
Subtraction: Example – A chemist opens a 1.0 x 104 mL bottle of 1 M
Hydrochloric acid (HCl) and removes 7.5 x 102 mL HCl. What volume is left in
the bottle?
Step 1: In order to subtract, the exponents must be the same. Convert the
second quantity to a multiple of 104 to match the first quantity.
7.5 x 102 mL HCl = 0.075 x 104 mL HCl
because the exponent is increased by two, the decimal point moves two places
to the left.
Step 2: Subtract. First line up the decimal points.
1.000 x 104 mL HCl
+ 0.075 x 104 mL HCl
0.925 x 104 mL HCl
Step 3: Convert to proper scientific notation!
0.925 x 104 mL HCl = 9.25 x 103 mL HCl
because the decimal point moves one place to the right, the exponent decreases
by one.
Scientific Notation: Multiplication
Multiplication: Example – At 25°C any sample of pure water contains the
following ion concentrations: 1.00 x 10-7 M H3O+ and 1.00 x 10-7 M OH-.
Calculate the product of these concentrations. This value is called the selfionization constant of water.
(1.00 x 10-7)x(1.00 x 10-7) = ?
Step 1: Multiply the coefficients.
1.00 x 1.00 = 1.00
Step 2: Add the exponents.
10-7 + -7 = 10-14
Step 3: Convert to proper scientific notation.
1.00 x 10-14
The answer is already in the proper notation because 1.00 is between 1 and
10.
Scientific Notation: Division
Division: Example – The hydroxide ion (OH-) concentration of an acid or base
solution can be found by dividing the self ionization constant of water (1.00 x
10-14) by the solution’s H3O+ concentration. If the H3O+ concentration is 3.00
x 10-5, what is the OH-concentration?
1.00 x 10-14 = [OH-]
3.00 x 10-5
Step 1: Divide the coefficients.
1/3 = 0.33
Step 2: Subtract the exponents.
10-14 - -5 = 10-9
Step 3: Convert to proper scientific notation.
0.33 x 10-9 = 3.3 x 10-10 = [OH-]
because the decimal point moves one place to the right, the exponent
decreases by one.
Acids and Bases Flashcards
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Front of card:
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Back of card:
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Vocabulary word
Picture/diagram
definition
Sentence using the word
Resources:
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Textbook Chapter 15
Words are also posted on
the wall.
Words
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Strong acid
Weak acid
Strong base
Weak base
Neutral
pH
Amphoteric
Bronsted-Lowry acid
Bronsted-Lowry base
Conjugate acid
Conjugate base
Hydronium ion
Hydroxide ion
Self-ionization constant of
water
Electrolyte
indicator
Independent Work Time
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Expectations:
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You may work on the following:
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You must work at your seat. You may speak quietly to the
students next to you.
Raise your hand if you need help.
You may get up to check your answers.
Scientific notation worksheet.
Acids and Bases Flashcards.
Answers are posted at the front of the class.
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Correct your work.
Homework
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Finish the scientific notation worksheet and your
flashcards.
I will collect your daily work organizer.
Highly recommended by optional: Buy a scientific
calculator and a white board marker.