INTRODUCTION AND MEASUREMENT How can we think like scientists? What is Chemistry? Why study Chemistry? How can problems be solved in a systematic manner? How do we give meaning and dimension to our descriptions of the world around us? How do round off answers to math problems? How is the data compression in mp3 and ZIP files mirrored in scientific notation? How can units be used to solve problems? How can we make sense of data and use it to make predications?

AIM: How can we think like scientists? Do Now: Have color coded PT out on table Have signed contract on table Read the instructions on the NOS Activity worksheet

Nature of Science Activity

Conclusion Brainstorm ideas about how this activity is similar to “doing” science? Hand in one sheet per table Put all pieces back in the bag, keep the extra piece separate

AIM: What is Chemistry? Chemistry is the study of the composition of substances and the changes they undergo It is the science of matter. It is considered the interaction between atoms Everything has chemistry, actually all matter has chemicals in it which is chemistry. For example, a table, a book, ink, and even us!

AIM: What is Chemistry? Divisions of Chemistry There are several divisions or branches of chemistry: Organic chemistry: the study of substances that contain carbon Example: How gasoline is produces from oil 2. Inorganic chemistry: the study of substances without carbon Example: how table salt reacts with different acids Analytical chemistry: the study of the quantitative composition of substances Examples: how much chlorine is in a sample of tap water Biochemistry: the study of chemistry of living organisms Examples: how sugar in the blood stream of cats affect insulin production

AIM: Why study chemistry? Helps us understand the world around us better Many questions can be answered by chemistry Anything you touch, taste or smell is a chemical. When we study chemistry we know a bit more about how things work

AIM: Why study Chemistry? - everyday examples Digestion; enzymes promoting chemical reactions that power our bodies. Lifting your arm requires your body to make and burn ATP using oxygen with carbon dioxide as one of the waste gases produced. The internal combustion engine takes liquid gasoline, converts it to a gas, burns it takes the waste to make mechanical energy and then expels some noxious gases. The rare metals in the catalytic converter scrub out the sulfuric acid, but we still get the ingredients for smog out of them. Cooking is the heating and combination of compounds to make something new. In some cases, like rising bread we have an actual chemical reaction where the yeast changes the food. When concrete dries and hardens the water actually causes a chemical reaction with the cement making a binding action drying concrete isn't just losing water it is undergoing a chemical change and one that creates heat as well (an exothermic reaction).

AIM: Why study Chemistry? - everyday examples When you write with ink on paper, the ink and paper unite in a chemical reaction so that you can't erase it. Specialized inks allow a short period where you can erase some inks, but most inks dry and can't be erased; they have bound with the paper. This includes your pen and your ink jet printer. Plastics are all about organic chemistry. The sun undergoes fusion and yes that too is chemistry. It creates radiation and photons so we can see. Some of the radiation interacts with oxygen to create ozone and the ozone layer shields us from harmful UV radiation. ANYTHING that burns is undergoing a chemical reaction and almost always creates some form of carbon as waste.

AIM: How can problems be solved in a systematic manner? The scientific method is a way to solve a scientific problem. It is an approach to a solution (using mostly common sense)

AIM: How can problems be solved in a systematic manner? - Steps of the Scientific Method Objective (Problem): statement of purpose Hypothesis (Prediction): Educated guess, in the form: if …. then… Experiment (Test): to test hypothesis, must give reproducible results to be reliable Variable: factor being tested Control: other factors that are held constant

AIM: How can problems be solved in a systematic manner? - Steps of the Scientific Method Observations (Data): collect and gather data based on your observations; organize these results to perform analysis in the form of charts, tables or graphs Conclusions: the determination if your hypothesis was correct, it may be accepted, rejected revised Follow up/application: a repeat with modification is sometimes necessary, and a reevaluation of the results. Also answering one question often leads to new questions. How could you use and communicate the information of your experiment. Why is it important and who could benefit from it?

AIM: How can problems be solved in a systematic manner? - Law vs. Theory Theory: explains the results of experiments, they can change or be rejected over time because of results from new experiments Law: describes natural phenomena, it tells what happens and does not attempt to explain why the phenomena occurs (that is the purpose of a theory). Laws can often be summarized by a math equation

AIM: How can we give meaning and dimension to our description of the world around us? – Metric System Measurement gives the universe meaning! How tall are you? How much do you weigh? How old are you? How fast can you run? How much volume do you displace? All of these questions are designed to give us reference to the world around us.

AIM: How can we give meaning and dimension to our description of the world around us? – Math Rules for Chem

AIM: How can we give meaning and dimension to our description of the world around us? – Sig Fig Rules Atlantic and Pacific Rule: If a decimal point is present (Pacific side) you start counting from left to right with the first non zero number If a decimal point is absent (Atlantic side) you start count from right to left with the first non zero number

AIM: How can we give meaning and dimension to our description of the world around us? – Sig Fig Rules Examples: 23.285 cm ________________ 8000 sec ________________ 40. L ________________ 2300 g ________________ 5 1 2 2

AIM: How do round off answers to math problems AIM: How do round off answers to math problems? – Calculating with sig figs  Multiplication and Division: want your answer to have the same number of SIG FIGS as the measurement that has the least number of sig figs  Examples: 3.1415 x 2.25 = 48.2 cm x 1.6 cm x 2.12 cm = 3 SF 7.07 160 2 SF

AIM: How do round off answers to math problems AIM: How do round off answers to math problems? – Calculating with sig figs Addition and Subtraction: want your answer to have the same number of DECIMAL PLACES as the measurement that has the least number of DECIMAL PLACES Examples: 6.357- 2.4 = 3.842 cm + 8.51cm + 16.324 cm = 4.0 1 DP 28.68 cm3 2 DP

AIM: How is the data compression in mp3 and ZIP files mirrored in scientific notation? - sci notation

AIM: How is the data compression in mp3 and ZIP files mirrored in scientific notation? - sci notation

AIM: How is the data compression in mp3 and ZIP files mirrored in scientific notation? - sci notation

AIM: How is the data compression in mp3 and ZIP files mirrored in scientific notation? - sci notation Comparing relative magnitudes of two numbers in scientific notation:

AIM: How can units be used to solve problems? - dimensional analysis To covert a measurement from one metric unit to another, you must know the difference in magnitude between the two prefixes and use the to create a conversion factor

AIM: How can units be used to solve problems? - dimensional analysis Use Reference Table C. If there is no prefix (m, g, L, etc.) then the power of ten is 100 . The prefix is underlined so you can verify its magnitude against Reference Table C. The smaller unit is italicized

AIM: How can units be used to solve problems? - dimensional analysis TO USE THE CONVERSION FACTOR: **NOTES: the number of sig figs in your final answer equals the number of sig figs in the number you are converting ** Given amount multiplied or divided by the conversion = answer If the given unit is also the numerator unit on the conversion factor, then DIVIDE to cancel it out If the given unit is also the denominator unit on the conversion factor, then MULTIPLY to cancel it out

- Convert a given result from one system of units to another DIMENSIONAL ANALYSIS - Convert a given result from one system of units to another - Unit factor method

Ex 1) A pin measuring 2.85 cm in length. What is its length in inches? Need an equivalence statement 2.54cm = 1in Divide both sides by 2.54cm Unit Factor Multiply any expression by this unit factor and it will not change its value

Ex 1) A pin measuring 2.85 cm in length. What is its length in inches? Pin is 2.85cm need to multiply by the unit factor 2.85𝑐𝑚 𝑥 1𝑖𝑛 2.54𝑐𝑚 = 2.85𝑖𝑛 2.54 =1.12𝑖𝑛

Ex 2) A pencil is 7.00 in long. What is the length in cm? Convert in  cm Need equivalence statement 2.54cm = 1in Unit Factor

DIMENSIONAL ANALYSIS 2.54𝑐𝑚 1𝑖𝑛 and 1𝑖𝑛 2.54𝑐𝑚 Unit factors can be derived from each equivalence statement 2.54cm = 1in 2 unit factors 2.54𝑐𝑚 1𝑖𝑛 and 1𝑖𝑛 2.54𝑐𝑚

DIMENSIONAL ANALYSIS and How to choose – look at direction of required change in  cm (need to cancel in – goes in denominator) cm  in (need to cancel cm – goes in denominator)

Ex 3) You want to order a bicycle with a 25 Ex 3) You want to order a bicycle with a 25.5in frame, but the sizes in the catalog are given only in cm. What size should you order? 25.5𝑖𝑛 𝑥 2.54𝑐𝑚 1𝑖𝑛 =25.5𝑥2.54𝑐𝑚=64.8𝑐𝑚

Ex 4) A student entered a 10.0-km run. How long is the run in miles? km  mi Equivalence statement 1m = 1.094yd Strategy first km  m  yards  mi Equivalence statements: 1km = 1000m 1m = 1.094 yd 1760yd = 1 mi

Ex 4) A student entered a 10.0-km run. How long is the run in miles? km  m 10.0𝑘𝑚 𝑥 1000𝑚 1𝑘𝑚 =1.00𝑥 10 4 𝑚

Ex 4) A student entered a 10.0-km run. How long is the run in miles? m  yd 1.00𝑥 10 4 𝑚 𝑥 1.094𝑦𝑑 1𝑚 =1.094𝑥 10 4 yd

Ex 4) A student entered a 10.0-km run. How long is the run in miles? yd  mi Original 10.0 which has 3 sig figs so you want 3 sig figs in your answer 1.094𝑥 10 4 yd 𝑥 1 𝑚𝑖 1760𝑦𝑑 =6.216𝑚𝑖=6.22𝑚𝑖

Ex 4) A student entered a 10.0-km run. How long is the run in miles? Can combine all conversions into one step 10.0km 𝑥 1000𝑚 1𝑘𝑚 𝑥 1.094𝑦𝑑 1𝑚 𝑥 1𝑚𝑖 1760𝑦𝑑 =6.22 𝑚𝑖

AIM: How can we make sense of data and use it to make predications AIM: How can we make sense of data and use it to make predications? - graphing Changing one thing in an experiment (independent variable) will often cause something else to change (dependent variable)