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IB/Accelerated Chemistry Larry J. Scheffler Lincoln High School 1600 SW Salmon Portland, OR 97205.

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Presentation on theme: "IB/Accelerated Chemistry Larry J. Scheffler Lincoln High School 1600 SW Salmon Portland, OR 97205."— Presentation transcript:

1 IB/Accelerated Chemistry Larry J. Scheffler Lincoln High School 1600 SW Salmon Portland, OR 97205

2 IB/Accelerated Chemistry Instructor : Mr. Larry J. Scheffler Web: Copy this web address and set a bookmark on your web browser. You will be using this site all year 2 IB/Accelerated Chemistry Instructor : Mr. Larry J. Scheffler Web:

3 Your Name Code name (use something that you will remember, I will post grades under that name) Address Telephone Number School ID Number Year in School Check previous math and science classes Check computer experience and skills Answer the four questions that follow Class Information Form 3

4 Periods 1, 3, and 5 Information forms Brief overview of the course Access to information on the internet Class Policies Safety contracts Chemical Hazards Scientific Methods Assignments IB Chemistr y 1-2 Agenda 4

5 IB Chemistry 1-2 Assignments Tomorrow: Read the Lab Density Determination Begin reading through Next week: Read chapter 1 in textbook Tuesday Sept 15: Return signed the PPS Safety Agreement and read thoroughly the chemical hazards handout 5

6 Introduction to Chemistry Chemistry The study of matter and its relationships The study of materials and how they interact The Central Science 6

7 Chemistry Topics Include Atomic Theory Periodic Table Bonding Formulas and Stoichiometry States of matter Calorimetry / Thermodynamics Solutions Kinetics Equilibrium Acids and Bases Oxidation Reduction 7

8 Is Chemistry Hard?? 8 Maybe! --- but you will develop skills that are valuable for the rest of your life!

9 Is Chemistry Hard?? Abstract Thinking Critical Thinking Analysis Logic Math Skills Well maybe but you will develop skills that are valuable for the rest of your life These include: 9

10 Is Chemistry Hard?? Abstract Thinking Critical Thinking Analysis Logic Math Skills Problem Solving Communication Time Management Hazards Management Well maybe but you will develop skills that are valuable for the rest of your life These include: 10

11 Chemical Hazards Hazard Criteria  A Threshhold Limit value of less than 500 ppm  A Lethal dose (LD50) less than 500mg per kg  Readily polymerizable  Flashpoint less than 140 o F  A strong oxidizer or reducing agent  Highly corrosive  Carcinogen, mutagen,or teratogen  Radioactive  See the handout for more definitions and criteria for chemical hazards 11

12 Scientific Methods Always based on observation and experimentation Observable and reproducible evidence are required to support conclusions 12

13 Scientific Method Investigation process - Preliminary observations - Formulation of a hypothesis -Design experiments to test the hypothesis -Evaluate and interpret data -Draw appropriate conclusions 13

14 Scientific Methods The scientific method is not necessarily a chronological order that scientists always follow. But remember ……….. Scientific information is always based on evidence. The emphasis is always on information that we can gain from observations and experiments Scientific information is always based on evidence. The emphasis is always on information that we can gain from observations and experiments 14

15 Hypothesis, Theory and Law A Hypothesis A Hypothesis is a tentative explanation or expected result based on past evidence and experience A Theory A Theory is an explanation of a phenomona based on the results of scientific experimentation. A Law A Law is a principle that can be observed repeatedly in the world over a long period of time 15

16 Matter Has both volume and mass Exists in various states: Solid Liquid Gas Plasma 16

17 Forms of Matter Element Compound Mixture Homogeneous Heterogeneous 17

18 Elemental Composition of the Earth

19 Properties of Matter Physical - Chemical - Extensive - Intensive - Color Density Melting point How the substance reacts with other substances Depend on the amount of material Independent of the amount of material 19

20 Density Definition Formula Ratio of mass to volume D = Mass/ volume Density is an intensive property. It is constant for most solids and liquids, but it depends on the pressure and temperature for a gas 20

21 Physical and Chemical Changes Physical - Chemical - A change in state or shape. Affects the physical properties but retains the properties of the substance Undergoes a chemical reaction. A new substance is formed with new physical and chemical properties 21

22 Problem Solving Density Formulas Density = Mass/volume D = m/V M = DV V = m/D Units Density = g/cm 3 Mass = grams or g Volume = cubic centimeters or cm 3 If you solve the formula correctly the units will match D = m/V = g/cm 3 M = DV = (g/cm 3 ) /(cm 3 ) = g V = m/D =(g)/(g/cm 3 ) = cm 3

23 Temperature Scales KelvinCelsiusFahrenheit Boiling point of water. 373 K100 o C212 o F Freezing point of water. 273 K100 o C32 o F Absolute Zero. 0 K-273 o C-460 o F 23

24 Temperature Conversions Fahrenheit to Celsius o C = 5/9 ( o F - 32) Celsius to Fahrenheit o F = 9/5 o C + 32 Celsius to Kelvin K = o C

25 Measurement Measurements in the laboratory will normally be made using the metric system and SI units where feasible 25

26 Measurement Issues Uncertainty Accuracy Precision Error Significant Figures Scientific Notation 26

27 Uncertainty in Measurements All measurements are limited by the instruments used to make them The uncertainty of a measurement depends on the quality with which a measurement is made The uncertainty depends on the precision and accuracy of the measurement 27

28 Accuracy and Precision Accuracy is the degree of closeness of a measured or calculated quantity to its actual (true) value. Precision is also called reproducibility or repeatability. It is the degree to which further measurements or calculations show the same or similar results. 28 Accuracy refers to the proximity of a measurement to the true value of a quantity. Precision refers to the proximity of several measurements to each other. In other words

29 Accuracy and Precision A measurement may be either accurate or precise, both or neither. 29

30 Significant Figures Only zeros can be non-significant digits There are two cases where a zero may be non significant: 30 A measurement is always limited by the precision of the Instrument. An understanding of significant figures is important to express the appropriate precision of a measurement 1.Zeros at the end of numbers greater than 1 that do not refer to a precise count 2. Zeros in front of the first non zero digit in numbers less than 1

31 Significant Figures The zeros shown in red are not significant. The number is precise to 4 significant digits With numbers having a zero at the end the number of significant figures depends on the precision with which the number is known one significant digit. The number is known to the nearest ten thousand three significant digits. The number is known to the nearest hundred five significant digits. The number is known to the nearest unit. 31

32 Scientific Notation Large numbers are hard to visualize. Scientific notation writes numbers in two parts: a number between 1 and 10 and a power of 10 Examples 3.00 x 10 8 rather than x rather than

33 Error The error in a measurement refers to the degree of fluctuation in a measurement. It is usually expressed as a + value Example: a measurement of a mass from the scale could be recorded as g g. It is often helpful to record measurements as relative error or percent error 33


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