Re-teach week continued Boon Chemistry January 10 and 11, 2013

Catalyst  Write at least five sentences answering any or all of the following questions:  What is your favorite type of environment for studying or doing homework?  Describe the place, time, noise level, other surrounding circumstances.  Write at least five sentences answering any or all of the following questions:  What is your favorite type of environment for studying or doing homework?  Describe the place, time, noise level, other surrounding circumstances.  Objectives  I can calculate the concentration of a solution.  I can describe the dissolving process on the molecular level.  I can perform scientific notation calculations.  Objectives  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  Catalyst  Benchmark Redo Quiz  Scientific Notation Review  Acids and Bases Vocabulary  Agenda  Catalyst  Benchmark Redo Quiz  Scientific Notation Review  Acids and Bases Vocabulary

Benchmark Redo Quiz  Expectations:  You will work silently and independently.  When you are done, cover your quiz with your handouts.  Tools:  You may use your concentration foldable and intermolecular forces handout to help you.  You may use your own calculator.  What do I turn in?  You will turn in your quiz, concentrations foldable, and intermolecular forces handout.

Scientific Notation  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 10 5 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  Thumbs up for proper scientific notation and thumbs down for incorrect scientific notation. 4.0 x 10 -2

Scientific Notation Quick Check  Thumbs up for proper scientific notation and thumbs down for incorrect scientific notation. 15 x 10 8

Scientific Notation: Conversions  To translate a number from scientific notation to standard form, look at the exponent on the x 10 5 If the exponent is positive move the decimal to the right. If the exponent is negative move the decimal to the left. 2.5 x x 10 5 = 250, x =

Scientific Notation: Conversions  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 10 4

Addition: Example – A chemist mixes a solution by combining 3.0 x 10 2 mL KOH to 5.0 x 10 3 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 10 3 to match the second quantity. 3.0 x 10 2 mL KOH = 0.30 x 10 3 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 x 10 3 mL KOH x 10 3 mL water Answer: 5.30 x 10 3 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: Addition

Scientific Notation: Subtraction Subtraction: Example – A chemist opens a 1.0 x 10 4 mL bottle of 1 M Hydrochloric acid (HCl) and removes 7.5 x 10 2 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 10 4 to match the first quantity. 7.5 x 10 2 mL HCl = x 10 4 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 x 10 4 mL HCl x 10 4 mL HCl x 10 4 mL HCl Step 3: Convert to proper scientific notation! x 10 4 mL HCl = 9.25 x 10 3 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 M H 3 O + and 1.00 x M OH -. Calculate the product of these concentrations. This value is called the self- ionization constant of water. (1.00 x )x(1.00 x ) = ? Step 1: Multiply the coefficients x 1.00 = 1.00 Step 2: Add the exponents = Step 3: Convert to proper scientific notation x 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 ) by the solution’s H 3 O + concentration. If the H 3 O + concentration is 3.00 x 10 -5, what is the OH - concentration? 1.00 x = [OH - ] 3.00 x Step 1: Divide the coefficients. 1/3 = 0.33 Step 2: Subtract the exponents = Step 3: Convert to proper scientific notation x = 3.3 x = [OH - ] because the decimal point moves one place to the right, the exponent decreases by one.

Acids and Bases Flashcards  Front of card:  Vocabulary word  Picture/diagram  Back of card:  definition  Sentence using the word  Resources:  Textbook Chapter 15  Words are also posted on the wall.  Words  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  Expectations:  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.  You may work on the following:  Scientific notation worksheet.  Acids and Bases Flashcards.  Answers are posted at the front of the class.  Correct your work.

Homework  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.