Jan. 9

Quiz. Write the answers on your own paper.

1. How do you know (by observation) that a chemical change has occurred?

2. In the chemical reaction: A + B C + D

A & B are called the _____. C & D are the ________.

3. What is “The Scientific Method”?

4. List the steps of the Scientific Method (at least five)

5. How is an observation different than an inference?

6. What is the difference between qualitative data and quantitative data?

7. When conversion factors are used in an equation, why is the validity of the equation notnot changed?

8. What is 5968473 times 9854334

Quiz Answers.

1. Something NEW is created.2. A and B are called the _reactants____________

C and D are called the _products____________3. The Scientific Method is an ordered and logical

approach to solve a problem/answer a question.4. question or problem, hypothesis, experiment, data,

conclusion5. Observation-using 5 senses; inference is a judgement

or assumption6. qualitative data-descriptions & quantitative-numbers7. Because the ratio is equal to the value of 1 and

multiplying by 1 does not change a value.8. 58815326411982 or 58815330000000 or 5.881533 x 1013

To Do Today

• Finish Grading Science Lab Notebooks and Return

• Finish Setting Up Science Lab Notebooks

• Discuss Success Strategies Handout

• Finish Powerpoint that follows

Dimensional Analysis

A Mathematical Technique

• Solving problems involving quantities or measurements using ratios and equivalent units.

• Using conversion factors• Conversion factors can be flipped

(nominator for denominator) to find desired units.

Express a mass of 5.712 grams in milligrams and kilograms

• Given = 5.712 grams (? Sign.digits)

• What equality relates grams to milligrams?

• 1 g = 1000 mg

• This can be written as “

1g/1000 mg or 1000 mg/1 g

• You are given grams and you are asked for a value in milligrams, so the conversion factor should be written as follows:

• 5.712 g x (1000mg) = 5712 mg

1 g

• Given grams and want kg, so the conversion factor should be written as follows:

• 5.712 g x ( 1 kg ) = 0.005712 kg 1000 g

On your paper, express 16.45 m in centimeters

• What conversion factor relates m to cm?

• 1 m = 100 cm

• How should this conversion factor be written to solve for cm?

1 m/100 cm or 100 cm/1 m

• 16.45 m (100 cm/1 m) = 1645 cm

On your paper, express 16.45 m in kilometers

• What conversion factor relates m to km?

• 1 km = 1000 m or 1 m = 0.001 km

• How should this conversion factor be written to solve for km?

1 km/1000 m or 1000 m/1 km

• 16.45 m (1 km/1000 m) = .01645 km

Express 0.014 mg in grams

• What conversion factor relates mg to g?

• 1000 mg = 1 g

• Written 1000mg/1 g or 1 g/1000mg?

• 0.014 mg (1 g/1000 mg) = 0.000014 g

• 1.4 x 10-5 g

DO YOUR OWN WORK

Complete p 42 1-6 and turn in

Recall Scientific Notation

• When numbers are written in the following form:

• M x 10n

• M is a number (greater than or equal to 1 and less than 10) (it can be positive or negative)

• n is a whole number (positive or negative)

Scientific Notation

• 65000 km is written as

• 6.5 x 104 km

• 65000 has 2 sign. digits

• 6.5 has 2 sign. digits

Scientific Notation

• 0.00012 mm is written as

• 1.2 x 10-4 mm

• There should be ONLY ONE nonzero digit on the left side of the decimal point!

• n is the number of places that the decimal point was moved. Moving the decimal to the left is shown as a positive n and moving it to the right is a negative n.

When doing calculations using scientific notation on your

calculator, Pg 52 of the textbook Shows how to use the EXP or EE

key.

Recall Significant Digits

• All measurements have some degree of uncertainty.

• The last reported digit is an estimation based on the sensitivity of the measuring tool.

• Be able to recognize the number of significant digits in a measured value.

• Report calculations only to the least number of sign. Digits as the least accurate measurement.

Recall the Atlantic Pacific Rule• If there is a decimal present, begin counting

from the left of the measurement.

• If there is no decimal, begin counting from the right of the measurement.

• Go to the first nonzero number and start counting.

• Do not stop counting until you reach the end.

Determine the number of significant digits :

• 28.6 g

• 3 sign. Digits

• 34410 cm

• 4 sign digits

• 0.0004500 m

• 4 sign. digits

Complete the Worksheet

• Significant digits

• Scientific Notation

• Dimensional Analysis

P 77 - STOP

• Counting atoms

• Mole

• Avogadro’s number

• Molar mass

• Gram/mole conversions

• Conversions with avogadro’s number

P 219

• Monatomic ions

• Binary ionic compounds

• Stock system for elements in d block

• Polyatomic ions

• Molecular compounds

P 237

• Formula mass

• Molar mass

• Percentage composition

• Calculation of empirical formulas

• Calculation of molecular formulas

Review equations and reactions

• Balancing equations

• P 268 – 9 molar ratios

• Types of reactions

• Predicting products

Stoichiometry

• Ch 9

Gases

• Gas law