Chapter 2 Analyzing Data

Bellwork Make a new section in your table of contents – Chapter 2: Analyzing Data Do not forget page numbers Beginning, ending, and throughout book Go to first blank page and write chapter 2 across it

Next Page – Copy Down Chapter Essential Question: How do scientists analyze data in order to determine how matter interacts? Lesson Essential Questions: Why do chemists use an international system of measurement? Why do measurements contain uncertainties and how can we counteract these?

Reminder!!! Essential questions from Chapters 1, 2, and 3 will be due on Exam day.

Chapter 2 Word Study Guide Four column definition activity Word, Definition, Your Definition, Picture/Example Words Accuracy Density Percent Error Precision Scientific Notation Significant Figures Conversions Base Units SI units

Bellwork/Homework Read Chapter 2 Complete the Chapter 2 Outline Do not just DEFINE words Give complete explanations

Problem How many Styrofoam cups equal Mrs. Stewart’s height??? GO!!! © 2013, Robert Ayton. All rights reserved.

Bellwork What information did you need to find out in yesterday’s launch lab? What mattered?

Styrofoam Cup Lab What mattered??? Lip Height of one Cup (the final cup) How Tall is Mrs. Stewart. y = mx + b © 2013, Robert Ayton. All rights reserved. Lip 1 Cup Height My Height # of Cups

Styrofoam Cup Lab What was the benefits of this lab? Measuring Forming Scientific Questions Data Collections Communication Connecting to Other Subject Areas © 2013, Robert Ayton. All rights reserved.

Metric Units In your journal, answer the following questions What are the base units for Time, Length, Mass, Temperature, and Volume. Discuss what density is, and how do you measure it. How do you convert between two different units.

Lets Complete a couple examples 2.34g  cg 456 dL  hL

Convert the following Numbers 0.026L  mL 832ks  hs 34,600 m  km 398.6dg  dag WHEN I TELL YOU!!!! Get with your shoulder partner and discuss your answers.

Journal Identify the equations used to convert between °C and K. As well as between °C and °F. Convert the following 365 K  °C 32°F  °C

Density When a piece of aluminum with a density of 2.7 g/mL is placed in a 25- mL graduated cylinder that contains 10.5 mL of water, the water level rises to 13.5 mL. What is the mass of the aluminum?

Practice Problems Complete problems 1-3 on page 38 Get with your shoulder partner and discuss your answers as well as the process.

Scientific Notation Is used to express any number as a number between 1 and 10 multiplied by 10 raised to a power.

Practice Using Scientific Notation Page 41 #’s 11 and 12 Get with your shoulder partner and discuss your answers. We will go over them as a class!

Understanding Check If a piece of metal has a density of 6.23 g/cm 3 and a mass of 12.4 g, what is the volume of the metal? Convert the following units 0.36 L  mL dm  km 43.6 hg  cg Put in Scientific Notation km mg Write in standard notation 3.6 x x 10 -7

Adding and Subtracting Scientific Notation Step 1: Notice if the powers of 10 are the same If they are bring straight down and add or subtract front numbers like normal If not, move to step 2 Step 2: Identify the highest power of 10 and keep it the same Step 3: Make the power of 10 the same as the higher number by moving the decimal left the correct number of spaces. Step 4: bring the power of 10 down, and then add or subtract front numbers like normal

Adding and Subtracting Examples Adding x x x x Subtracting x x x x

Bellwork: Adding and Subtracting Scientific Notation MOVE DECIMAL TO MAKE THE POWER OF 10 THE SAME!!! Go with the highest exponent Practice Problems pg 42 13cd and 14cd

Bellwork Turn in weekend homework problems Review adding and subtracting scientific notation with your shoulder partner. (8.6 x 10 5 ) – (2.2 x 10 3 ) (7.2 x kg) + (6.8 x g) in grams

Multiplying and dividing scientific Notation Step 1: Identify whether you are multiplying or dividing Step 2: if multiplying, add exponents. If dividing, subtract exponents. Step 3: Multiply or divide front numbers like normal Step 4: Make sure your final answer is in correct scientific notation.

Multiplying and Dividing Examples Multiplying x 10 5 x1.6 x x 10 2 x 5.2 x Dividing x 10 8 / 1.3 x x 10 4 / 3.6 x

Multiplying and Dividing Scientific Notation IF MULTIPLYING, ADD powers of 10. If DIVIDING, SUBTRACT powers of 10. Practice Problems pg 43 15bd and 16bd

Review Complete the following problems (2.3 x 10 2 ) – (9.2 x 10 3 ) (3.4 x kg) + (6.8 x kg) (2.35 x 10 3 ) x (6.00 x 10 5 ) (4.3 x 10 2 )/(7.38 x 10 4 )

Accuracy Data The true value is.5g The students experimental values are:.51g.49g.5g.52g

Precision Data The true value is.5g The students experimental values are:.8g.81g.79g

Accuracy vs. Precision

Error Three Key Components 1.Accepted Value 1.A value determined correct through mathematical calculations 2.Experimental Value 1.A value determined through experimentation (your value) 3.Error 1.How far the experimental value is from the accepted value.

Example: Error=Experimental value-accepted value Joshua uses his thermometer and finds the boiling point of ethyl alcohol to be 75 o C. He looks in a reference book and finds that the actual boiling point of ethyl alcohol is 80 o C. What is his error?

Percent Error Equation on page 48 Percent error = ( error /accepted value) x 100 Percent error expresses error as a percentage of the accepted value Most commonly used error expression Must have: error and accepted value to calculate Example The density of water at 4 o C is known to be 1.00 g/mL. Kayla experimentally found the density of water to be g/mL. What is her percent error?

Practice Problems You may work with your shoulder partner Examples page

Copy: Significant Figures Rules Every NON ZERO digit is significant Zeros to the LEFT of the first non-zero digit is NEVER significant Zeros in the MIDDLE of two non-zero digits are ALWAYS significant Zeros to the Right of the LAST non-zero digit are SOMETIMES significant If you see a decimal = YES! If you DO NOT see a decimal = NO! Counting numbers and ratios/conversions have an infinite number of significant figures.

Rule 1: Every NON ZERO digit is significant Examples: 1234 = 4 significant figures 2.34 = 3 significant figures 14,567 = 5 significant figures How many significant figures in the following numbers?

Rule 2: Zeros to the LEFT of the first non-zero digit is NEVER significant Steps Find 1 st non-zero digit Cross out all zeros in front of it Examples = 2 significant figures = 4 significant figures Practice

Rule 3: Zeros in the MIDDLE of two non- zero digits are ALWAYS significant This means all zeros surrounded by non-zero digits are ALWAYS counted as significant. Example: = 5 significant figures 2001 = 4 significant figures = 9 significant figures Practice Problems

Rule 4: Zeros to the Right of the LAST non- zero digit are SOMETIMES significant Steps Identify last non-zero digit If there are zeros to the right, then look for a decimal somewhere in the number If you see a decimal = YES!! If no decimal = NO! Example = 5 significant figures (decimal) = 2 significant figures (no decimal) Practice Problems

Rule 5: Counting numbers and ratios/conversions have an infinite number of significant figures. If you are counting an object there are infinite significant figures Ex: 8 computers = infinite significant figures Ex: 26 students = infinite significant figures If you have a conversion or ratio the are infinite significant figures Ex: 1000mm = 1m = infinite Ex: 12 eggs = 1 dz

Key Points All non zeros are significant Left zeros = never Middle Zeros = Always Right Zeros = Only if there is a decimal

Examples Determine the number of significant figures in the following measured values

Practice Problems Pg 51 #’s 35-37

Bellwork Convert 40g  mg km  cm 36°C  K Scientific Notation (2.4 x 10 3 ) + (3.6 x 10 2 ) (3.5 x 10 6 ) / (1.7 x 10 8 ) Accuracy vs. Precision Explain the difference between accuracy and precision Error A student completed their experiment and wanted to calculate their percent error. The teacher explained that the precipitate should have had a mass of 4.8g. The student calculated a mass of 3.4g. Help the student calculate their percent error!

Adding and Subtracting Sig Fig’s Round to the lowest amount of decimal places Examples = 4.6 x x Practice Problems: Pg 53 #’s 40 and 41

H.W. Practice problems Chemistry Handbook Page 18 #’s 24a-d and 25 ab Separate sheet of paper

Multiplying and Dividing Sig Figs Round to the lowest number of significant figures Examples 1.3 x 0.2 x 3.26 = 3.46 x 10 3 /.60 x Practice Problems: 42ab, 43cd, 44 (pg 54)

Journal Entry – 5 min Write down all the rules for SIGNIFICANT FIGURES! How do you round when you add and subtract? How do you round when you multiply and divide?

Significant Figures Worksheet 1.With your shoulder partner, complete the worksheet in your COMPOSITION BOOK. 2.When told to do so, you will get with another partner and come up with a consensus on a separate sheet of paper for all answers 3.Turn in consensus paper for a GRADE

Bellwork TURN IN EQs RIGHT NOW!!!! Get with your shoulder partner and continue working on the worksheet You have about 15 minutes Test you need Two sheets of paper Pencil Calculator

Complete Practice Problems (Shoulder Partner) 32 (pg49), 35ac,36ac, 37 (pg 51), 38ab, 39ab, 40, 41 (pg53),42ab,43ab,44 (pg54)