Chemistry Monday, January 23, 2017

Transcription

1 Chemistry Monday, January 23, 2017 Do-Now: Ch. 11 Quiz Review 1. Write down today s FLT 2. List three symbols used in chemical equations, and state their meaning. 3. Copy: S 8 + O 2 à SO 2 4. Identify the type of reaction in #3. 5. Balance the equation in #3. Show all work. Take out your planner and ToC Announcements Scien&fic calculators! A2end tutoring as needed Use dojo points Reminder: retakes Bring quizzes you wish to retake Clear missing work Planner: Read Ch. 3 Bring calculators! Lab Safety: hair tied back + close-toed shoes Table of Contents #1: 10. Ch. 11 Quiz Review Do-Now FLT I will be able to demonstrate my understanding of chemical reactions by completing Ch. 11 Quiz Standard HS-PS1-7: Use mathema2cal representa2ons to support the claim that atoms, and therefore mass, are conserved during a chemical reac2on Quiz Protocol Clear your desks Noise level 0 Eyes on your own paper Check answers when finished Flip over when finished 1

2 Read Ch. 3 CW Chemistry Tuesday, January 24 Wednesday, January 25, 2017 Do-Now: Lab Day On the back of your packets: 1. Write down today s FLT 2. List at least 8 important things to remember in the lab. These can include safety rules, how to dress, and how to clean after. 3. Start reading over the lab. Take out your planner and ToC Announcements Scien&fic calculators! A2end tutoring as needed Use dojo points Retakes Before school Lunch ALer school by appointment only (Tues/Thurs) Planner: Finish lab packets and turn in to HW box Bring calculators Retake quiz (if needed) Table of Contents #1: 10. Ch. 11 Quiz Review Do-Now 2

3 FLT I will be able to observe the signs of chemical reactions by completing Reaction Lab Standard HS-PS1-7: Use mathema2cal representa2ons to support the claim that atoms, and therefore mass, are conserved during a chemical reac2on Some Signs of a Chemical Rxn 1. Produc&on of an odor 2. Change in temperature 3. Change in color 4. Forma&on of bubbles 5. Forma&on of a solid Lab Overview 1. Hair must be &ed back 2. Goggles must be on 3. Wear gloves 4. Hold tongs carefully 5. Rinse out materials at each sta&on before moving to the next 6. Record very detailed observa&ons Lab Overview Two types of observa&ons: Qualita&ve = uses the 5 senses The beaker feels warm The solu2on looks cloudy Quan&ta&ve = uses numbers/ measurements I added 10 drops The mass was 4.6 grams CW Post-Lab Ques&ons Read Ch. 3 3

4 Chemistry Thursday, January 26 Friday, January 27, 2017 Do-Now: Cornell Notes Ch.3 A 1. Write down today s FLT 2. What is rounded to the nearest a. Hundredths b. Tenths c. Ones d. Tens e. Hundreds 3. Why do you think we round numbers? 4. Turn in your labs if finished. Take out your planner and ToC Announcements Scien&fic calculators! A2end tutoring as needed Use dojo points Reminder: retakes Bring quizzes you wish to retake Clear missing work Planner: Ch. 3 Quiz next week (short chapter) Get stamps! Table of Contents #1: 11. Ch. 3 A Cornell Notes 12. Sig Figs Packet FLT I will be able to determine the number of significant figures in a measurement by completing Ch. 3 A Notes Ch. 3: Scientific Measurement Standard HS-PS1-7: Use mathema2cal representa2ons to support the claim that atoms, and therefore mass, are conserved during a chemical reac2on 4

5 Ch. 3 A Cornell Notes Add assignment # Copy down all bolded ideas Noise level 0 Raise hand to question/comment Be prepared to pair-share-respond We often take measurements in chemistry labs Are our measurements accurate? This depends on: The reliability of the measuring instrument the care with which it is read this is determined by YOU! Video Notes Write down four facts or examples from the video clip 5

6 Accuracy vs. Precision Accuracy, Precision, and Error It is necessary to make good, reliable measurements in the lab Accuracy how close a measurement is to the true value Precision how close the measurements are to each other (reproducibility) Precision and Accuracy Why Is there Uncertainty? are performed with instruments, and no instrument can read to an infinite number of decimal places Which of the balances below has the greatest uncertainty in measurement? Neither accurate nor precise Precise, but not accurate Precise AND accurate A Brief Review of Scientific Notation Sig Figs 6

7 Significant Figures in Significant figures = all known digits plus one estimated digit must be reported to the correct number of significant figures. Significant Figures in If you don t use the correct sig figs, your answer is incorrect L Rules for Counting Sig Figs Rules for Sig Figs -Nonzero digits are always significant Ex/ sig figs 7

8 Rules for Counting Sig Figs -Leading zeroes are NOT significant Ex/ sig figs Rules for Counting Sig Figs -Zeroes in between significant digits are also significant Ex/ sig figs Rules for Counting Sig Figs Trailing zeroes are significant if they are before or after a decimal point Ex/ sig figs Ex/ sig figs Rules for Counting Significant Figures Counted items & defined quantities have unlimited sig figs Counted items 23 people, or 425 thumbtacks Exactly defined quantities 60 minutes = 1 hour Pair-Share-Respond How many significant figures in the following? m à 5 sig figs kg à 4 sig figs 100,890 L à 5 sig figs 1 M < 10 M x 10 n n is an integer 3.29 x 10 3 s à 3 sig figs cm à 2 sig figs 3,200,000 ml à 2 sig figs 5 dogs à unlimited This is a counted value 8

9 Significant Figures in Calculations In general a calculated answer cannot be more precise than the least precise measurement from which it was calculated. Ever heard that a chain is only as strong as the weakest link? Sometimes, calculated values need to be rounded off. Rounding Calculated Answers 1. Determine how many sig figs are needed 2. Round your answer to the correct number of sig figs Rounding Calculated Answers + and - Round to the number with the fewest decimal places Ex/12.25 m m m m Rounding Calculated Answers and Round answer to the smallest # of sig figs present Ex/ 6.38 x 2.0 = à 13 (2 sig figs) Ex/2.10 meters x 0.7 meters = 1 meter Pair-Share-Respond Calculation Calculator says: Answer 3.24 m x 7.0 m m 2 23 m g 23.7 cm g/cm g/cm 3 CW Sig Fig Packet ToC and/or study Ch cm x cm cm cm m 3.0 s m/s 240 m/s lb x 3.23 ft lb ft 5870 lb ft g x 2.87 ml g/ml 2.96 g/ml 9