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? not 7.When conversion factors are used in an equation, why is the validity of the equation not changed? 8.What is times

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, conclusion 5.Observation-using 5 senses; inference is a judgement or assumption 6.qualitative data-descriptions & quantitative-numbers 7.Because the ratio is equal to the value of 1 and multiplying by 1 does not change a value or or x 10 13

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 grams in milligrams and kilograms Given = 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: g x (1000mg) = 5712 mg 1 g

Given grams and want kg, so the conversion factor should be written as follows: g x ( 1 kg ) = kg 1000 g

On your paper, express 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 m (100 cm/1 m) = 1645 cm

On your paper, express m in kilometers What conversion factor relates m to km? 1 km = 1000 m or 1 m = km How should this conversion factor be written to solve for km? 1 km/1000 m or 1000 m/1 km m (1 km/1000 m) = km

Express mg in grams What conversion factor relates mg to g? 1000 mg = 1 g Written 1000mg/1 g or 1 g/1000mg? mg (1 g/1000 mg) = g 1.4 x g

DO YOUR OWN WORK Complete p and turn in

Recall Scientific Notation When numbers are written in the following form: M x 10 n 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 km is written as 6.5 x 10 4 km has 2 sign. digits 6.5 has 2 sign. digits

Scientific Notation mm is written as 1.2 x 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 cm 4 sign digits 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