CHAPTER 1LABORATORY CHEMISTRY1 CHAPTER 1 CHEMISTRY AND YOU

CHAPTER 1LABORATORY CHEMISTRY2 WHAT IS CHEMISTRY? n CHEMISTRY IN ACTION –THE CENTRAL SCIENCE n CHEMISTRY OVERLAPS SO MANY SCIENCES –WHAT IS CHEMISTRY ? –WHY STUDY CHEMISTRY?

CHAPTER 1LABORATORY CHEMISTRY3 WHAT IS CHEMISTRY? n What is chemistry? n How can a knowledge of chemistry help a wetlands ecologist or an archeologist do her job? n Suppose you know a hair stylist who tells you that in his profession he has no need to understand chemistry. What arguments would you use to convince him that he was mistaken?

CHAPTER 1LABORATORY CHEMISTRY4 THE SCIENTIFIC METHOD n A SYSTEMATIC APPROACH –A WAY OF ANSWERING QUESTIONS AND/OR SOLVING PROBLEMS n STEPS OF THE SCIENTIFIC METHOD –OBSERVATION n LEADS TO A QUESTION OR DISCOVERS A PROBLEM n RESEARCH (OBSERVATION, LIBRARY, OTHER) –HYPOTHESIS n A TENTATIVE ANSWER TO THE QUESTION –EXPERIMENT n SCRUPULOUS RECORD KEEPING n ANALYZE DATA –CONCLUSION n BASED ON THE EXPERIMENTAL DATA –REPEAT EXPERIMENTATION Hello! I am the Chemistry Mole ! You will see me, or one of my other mole friends, from time-to-time during this course….when you see us it will mean the material is considered “essential content” and will be on the Final Exam ! MOLE

CHAPTER 1LABORATORY CHEMISTRY5 THE SCIENTIFIC METHOD OBSERVATION QUESTION HYPOTHESIS EXPERIMENT CONCLUSION NATURAL LAW THEORY (MODEL) THEORY MODIFIED AS NEEDED PREDICTION EXPERIMENT REPEAT (EXPERIMENT)

CHAPTER 1LABORATORY CHEMISTRY6 THE SCIENTIFIC METHOD n INTERPRETING RESULTS –EXPERIMENTAL CONTROLS n A CONTROL RESPONDS IN A PREDICTABLE WAY TO THE EXPERIMENT. n LAWS AND THEORIES –NATURAL LAW n DRAWS TOGETHER MANY OBSERVATIONS AND THE RESULTS OF MANY EXPERIMENTS INTO A “BIG PICTURE” n DOES NOT EXPLAIN WHAT THE PICTURE MEANS –THEORY n PROVIDES EXPLANATION

CHAPTER 1LABORATORY CHEMISTRY7 THE SCIENTIFIC METHOD n What is the scientific method? n List the steps of the scientific method. n What is a variable? An experimental control? n What is the difference between a natural law and a scientific theory?

CHAPTER 1LABORATORY CHEMISTRY8 UNITS OF MEASURE THE INTERNATIONAL SYSTEM OF UNITS ( SYSTEME INTERNATIONAL D’ UNITES ) THE INTERNATIONAL SYSTEM OF UNITS ( SYSTEME INTERNATIONAL D’ UNITES ) –BUILT ON A SET OF SEVEN METRIC UNITS WHICH ARE CALLED THE BASE UNITS OF THE SI

CHAPTER 1LABORATORY CHEMISTRY9 UNITS OF MEASURE masskilogramkg lengthmeterm timeseconds count, quantitymolemol temperaturekelvinK electric currentampereA luminous intensitycandelacd PHYSICAL QUANTITYUNIT NAME SYMBOL SI BASE UNITS

CHAPTER 1LABORATORY CHEMISTRY10 UNITS OF MEASURE n DERIVED UNITS –IN ADDITION TO THE SEVEN BASE UNITS, OTHER SI UNITS CAN BE MADE FROM COMBINATIONS OF THE BASE UNITS. USUALLY A CALCULATED VALUE…NOT A MEASUREMENT ! AREA (m 2 ) = LENGTH (m) x WIDTH (m)

CHAPTER 1LABORATORY CHEMISTRY11 UNITS OF MEASURE areasquare meterm 2 volumecubic meterm 3 forcenewtonN pressurepascalPa energyjouleJ powerwattW voltagevoltV frequencyhertzHz electric chargecoulombC PHYSICAL QUANTITYUNIT NAMESYMBOL DERIVED UNITS USED IN CHEMISTRY

CHAPTER 1LABORATORY CHEMISTRY12 UNITS OF MEASURE n NON SI UNITS USED IN CHEMISTRY –IN ADDITION TO THE BASE AND DERIVED SI UNITS THERE ARE OTHER UNITS COMMONLY USED IN CHEMISTRY n THESE ARE NOT SI UNITS, HOWEVER THEY ARE REGULARLY USED IN THE STUDY OF CHEMISTRY

CHAPTER 1LABORATORY CHEMISTRY13 UNITS OF MEASURE volumeliterL pressureatmosphereatm millimeters of mercurymmHg temperatureCelsius degreeC o energycaloriescal PHYSICAL QUANTITYUNIT NAME SYMBOL NON-SI UNITS USED IN CHEMISTRY

CHAPTER 1LABORATORY CHEMISTRY14 UNITS OF MEASURE n METRIC PREFIXES –A METRIC PREFIX IS ATTACHED TO THE BASE UNIT, CREATING A MORE CONVENIENT, EASIER TO USE UNIT. –PREFIXES CAN MAKE THE NEW UNIT LARGER OR SMALLER THAN THE BASE UNIT

CHAPTER 1LABORATORY CHEMISTRY15 UNITS OF MEASURE COMMON PREFIXES Giga-G mega-M kilo-k hecto-h deka-D (Dk) ROOT UNITmeter, liter, gram deci-d centi-c milli-m micro-  nano-n pico-p PREFIX ABBREVIATIONVALUE SCI. NOTATION

CHAPTER 1LABORATORY CHEMISTRY16 UNITS OF MEASURE n What are the SI units for length, mass, and volume? n What is a metric prefix? What does the metric prefix centi- mean? The prefix deci- ? n What is the difference between mass and weight?

CHAPTER 1LABORATORY CHEMISTRY17 UNCERTAINTY IN MEASUREMENT n MAKING MEASUREMENTS –IN MAKING A MEASUREMENT, YOU WRITE DOWN ALL OF THE CERTAIN (OR EXACT) DIGITS THAT THE INSTRUMENT CAN GIVE AND ALSO ONE UNCERTAIN DIGIT YOU ESTIMATE. –MEASUREMENTS ARE UNCERTAIN FOR TWO REASONS: n 1.MEASURING INSTRUMENTS ARE NEVER COMPLETELY FREE OF FLAWS. n 2.MEASURING ALWAYS INVOLVES SOME ESTIMATION.

CHAPTER 1LABORATORY CHEMISTRY18 UNCERTAINTY IN MEASUREMENT n ESTIMATING WITH A DIGITAL DISPLAY –Instruments with a digital display n The final digit is the estimated digit n The estimated digit is done for you electronically –it can sometimes “flicker”, if this happens you should record the reading that instrument “prefers”. –REMEMBER TO LABEL YOUR MEASUREMENT (GRAM, KILOGRAM, o C, etc.)

CHAPTER 1LABORATORY CHEMISTRY19 UNCERTAINTY IN MEASUREMENT n ESTIMATING WITH A SCALE MINISCUS 23  1

CHAPTER 1LABORATORY CHEMISTRY20 UNCERTAINTY IN MEASUREMENT n RELIABILITY IN MEASUREMENT –THERE ARE TWO WAYS TO CHECK RELIABILITY n PRECISION:REPEAT THE MEASUREMENT SEVERAL TIMES….A RELIABLE MEASUREMENT WILL GIVE ABOUT THE SAME RESULT AGAIN AND AGAIN. n ACCURACY:THE SECOND WAY IS TO CHECK THE RESULTS AGAINST A STANDARD. A MEASUREMENT THAT IS ACCURATE IS ONE THAT IS CLOSE TO THE ACCEPTED STANDARD.

CHAPTER 1LABORATORY CHEMISTRY21 UNCERTAINTY IN MEASUREMENT PRECISE BUT NOT ACCURATE BOTH PRECISE AND ACCURATE NOT PRECISE NOR ACCURATE

CHAPTER 1LABORATORY CHEMISTRY22 UNCERTAINTY IN MEASUREMENT n Explain why measurements are always uncertain. n Describe two ways to check the reliability of a measurement. n How would you find the uncertain digit in a measurement using a digital display? Using a scale ?

CHAPTER 1LABORATORY CHEMISTRY23 WORKING WITH NUMBERS n SIGNIFICANT DIGITS –WHEN MEASUREMENTS ARE COMBINED MATHEMATICALLY, THE UNCERTAINTY OF THE SEPARATE MEASUREMENTS MUST BE CORRECTLY REFLECTED IN THE FINAL RESULT. –THE CERTAIN DIGITS AND THE ESTIMATED DIGIT OF A MEASUREMENT ARE TOGETHER CALLED THE SIGNIFICANT DIGITS OF THE MEASUREMENT.

CHAPTER 1LABORATORY CHEMISTRY24 WORKING WITH NUMBERS n WHEN A ZERO IS NOT SIGNIFICANT –A ZERO THAT IS SIMPLY A PLACE-KEEPER IN A MEASUREMENT IS NOT SIGNIFICANT. –TO DETERMINE IF A ZERO IS SIGNIFICANT OR NOT SIGNIFICANT FOLLOW THIS SIMPLE METHOD.

CHAPTER 1LABORATORY CHEMISTRY25 WORKING WITH NUMBERS READ FROM THE LEFT AND BEGIN COUNTING SIGNIFICANT DIGITS AT THE FIRST NUMBER OTHER THAN ZERO IF THERE IS A DECIMAL IN THE NUMBER…. ZEROS AT THE END OF THE NUMBER CHAIN COUNT ! IF THERE IS NO DECIMAL IN THE NUMBER THE FINAL ZERO(S) DO NOT COUNT !

CHAPTER 1LABORATORY CHEMISTRY26 WORKING WITH NUMBERS n SIGNIFICANT DIGITS IN CALCULATIONS –WHEN AN EXACT NUMBER APPEARS IN A CALCULATION, IT DOES NOT AFFECT THE NUMBER OF SIGNIFICANT DIGITS IN THE FINAL ANSWER. n EXACT NUMBERS ARE NOT MEASUREMENTS, BUT ARISE FROM A DEFINITION (I.E. 100O METERS = 1 KILOMETER) THIS IS A DEFINITION, NOT A MEASUREMENT! –A DEFINITION HAS AN INFINITE NUMBER OF SIGNIFICANT DIGITS

CHAPTER 1LABORATORY CHEMISTRY27 WORKING WITH NUMBERS –IN MULTIPLICATION AND DIVISION n THE MEASUREMENT WITH THE SMALLEST NUMBER OF SIGNIFICANT DIGITS DETERMINES HOW MANY DIGITS ARE ALLOWED IN THE FINAL ANSWER. –IN ADDITION AND SUBTRACTION n THE NUMBER OF SIGNIFICANT DIGITS ALLOWED DEPENDS ON THE NUMBER WITH THE LARGEST UNCERTAINTY.

CHAPTER 1LABORATORY CHEMISTRY28 WORKING WITH NUMBERS SIGNIFICANT DIGITS 6 SIGNIFICANT DIGITS 3 SIGNIFICANT DIGITS 5 SIGNIFICANT DIGITS

CHAPTER 1LABORATORY CHEMISTRY29 WORKING WITH NUMBERS X

CHAPTER 1LABORATORY CHEMISTRY30 WORKING WITH NUMBERS n SCIENTIFIC NOTATION –CONVERTING NUMBERS TO SCIENTIFIC NOTATION n TO WRITE NUMBERS IN SCIENTIFIC NOTATION, THE PROPER EXPONENT CAN BE FOUND BY COUNTING HOW MANY TIMES THE DECIMAL POINT MUST BE MOVED TO BRING IT TO ITS FINAL POSITION SO THAT THE NUMBER IS BETWEEN 1 AND 10. n IF THE NUMBER IS LESS THAN 1 THE EXPONENT OF 10 IS NEGATIVE 10 -X n IF THE NUMBER IS GREATER THAN 1 THE EXPONENT IS POSITIVE 10 X

CHAPTER 1LABORATORY CHEMISTRY31 WORKING WITH NUMBERS 32, X 10 4 O.OOO341 45,500, X X X 10 -5

CHAPTER 1LABORATORY CHEMISTRY32 WORKING WITH NUMBERS 32, X X , X X X 10 0

CHAPTER 1LABORATORY CHEMISTRY33 WORKING WITH NUMBERS n PERCENTS AND PERCENT ERROR n RATIOS MEASURED VALUE - ACCEPTED VALUE ACCEPTED VALUE X 100 THEORETICAL EXPERIMENTAL THEORETICAL ACCEPTED VALUE ACCEPTED AMOUNT GIVEN VALUEGIVEN AMOUNT IF THEN =

CHAPTER 1LABORATORY CHEMISTRY34 WORKING WITH NUMBERS n What are significant digits? n Describe how the Atlantic-Pacific rule can be used to help find the significant digits in a measurement. n How can you calculate the density of an object?

CHAPTER 1LABORATORY CHEMISTRY35 PROBLEM SOLVING n FOUR STEP PROBLEM SOLVING STRATEGY –ANALYZE: n READ THE ENTIRE PROBLEM CAREFULLY. n IDENTIFY THE UNKNOWN QUANTITY IN THE PROBLEM AND CHOSE A SYMBOL TO REPRESENT IT n ORGANIZE THE GIVEN INFORMATION (USE A TABLE OR LIST) n SKETCH A PICTURE OR DIAGRAM TO HELP CLARIFY THE PROBLEM

CHAPTER 1LABORATORY CHEMISTRY36 PROBLEM SOLVING –PLAN: n IS THE PROBLEM SIMILAR TO ANY YOU HAVE SEEN BEFORE? n REVIEW EARLIER PROBLEMS FOR CLUES TO CONNECTING THE UNKNOWN TO THE GIVEN INFORMATION n WRITE DOWN ANY EQUATIONS THAT LINK THE UNKNOWN AND THE GIVENINFORMATION TOGETHER n MAKE A PLAN FOR SOLVING THE PROBLEM n MAKE AN ESTIMATE OF THE ANSWER (“WHAT WOULD BE A REASONABLE ANSWER IN THIS CASE?”)

CHAPTER 1LABORATORY CHEMISTRY37 PROBLEM SOLVING –SOLVE: n PERFORM THE MATHEMATICAL STEPS OUTLINED IN YOUR PLAN. n CHECK UNITS AND SIGNIFICANT DIGITS –EVALUATE: n ASK YOURSELF, DOES THIS ANSWER THE QUESTION ? n DOES THE ANSWER MAKE SENSE? n COMPARE THE ANSWER (NUMERICAL VALUE AND UNITS) WITH YOUR ESTIMATE.

CHAPTER 1LABORATORY CHEMISTRY38 PROBLEM SOLVING CONVERSIONS CONVERTING WITHIN THE SI SYSTEM CONVERSIONS IN THE SAME DIMENSION USING LINEAR, SQUARE, AND CUBIC MEASUREMENTS CONVERSIONS IN DIFFERENT DIMENSIONS CHANGING CUBIC, MASS AND VOLUME MEASUREMENTS USING WATER

CHAPTER 1LABORATORY CHEMISTRY39 PROBLEM SOLVING: Conversions Convert 234 mL into L. Step 1 Kilo Hecto Deka Standard (m, L,g) deci centi milli You are at milli- You want to go to Liters That’s three steps

CHAPTER 1LABORATORY CHEMISTRY40 PROBLEM SOLVING: Conversions Step 2 Write the number in scientific notation Write the number by placing the decimal Behind the first number (other than zero) Write the exponential notation (x 10 ) X 10 Count the number of places you need to move the decimal to get back to the original number…in this case “2”..use that number as the exponent of 10 2

CHAPTER 1LABORATORY CHEMISTRY41 PROBLEM SOLVING: Conversions Step 3 Final Conversion Write the “Conversion Factor” (1.0 x 10 ) 2.34 x x 10 Make the exponent of 10 the number of steps you counted in Step 1 If you went UP the scale make it negative (-) If you went DOWN the scale make it positive (+) 2.34 x Now simply multiply the two numbers (remember your math rules [add exponents]) And that’s the answer! 1.0 x ? x

CHAPTER 1LABORATORY CHEMISTRY42 PROBLEM SOLVING: Conversions SUMMARY 234 mL = 2.34 x L 2.34 x x x x

CHAPTER 1LABORATORY CHEMISTRY43 PROBLEM SOLVING n DIMENSIONAL ANALYSIS –THE TECHNIQUE OF CONVERTING BETWEEN UNITS –UNIT EQUALITIES: AN EQUATION THAT SHOWS HOW DIFFERENT UNITS ARE RELATED n METRIC TO METRIC n ENGLISH TO METRIC –CONVERSION FACTORS: AN EQUATION THAT IS ALWAYS EQUAL TO ONE (1).

CHAPTER 1LABORATORY CHEMISTRY44 PROBLEM SOLVING: Dimensional Analysis Dimensional Analysis is an extension of the Conversion method we just used. The most important Concept here is to “ORGANIZE” the problem. Don’t let the number of steps frighten you! 157 m 3 = ___________ Kg In all of these problems we are dealing with water (H 2 O) at standard conditions (Standard Temperature and Pressure) (STP). Which is 0 o C and 1 atm. Since water has a density of 1 g/cm 3 at Standard Conditions….We can equate: 1 g = 1 mL = 1cm 3

CHAPTER 1LABORATORY CHEMISTRY45 PROBLEM SOLVING: Dimensional Analysis Organizaton First: Write the problem! Second: Set the proper equality under the problem Third: Plan your problem.. Use arrows to determine the Direction of movement. 157 L = ___________ Kg mL = _____________ g

CHAPTER 1LABORATORY CHEMISTRY46 Remember that mL and Grams Equate (1 mL = 1 g) PROBLEM SOLVING: Dimensional Analysis 157 L = ___________ Kg mL = _____________ g 1 2 Basically, what you have done was to arrange the problem into two(2) simple conversions! 157 L = _____________ mL g = _____________ Kg 1 2

CHAPTER 1LABORATORY CHEMISTRY47 PROBLEM SOLVING: Dimensional Analysis 157 L = ____________ Kg mL = ____________ g L = _________ mL g = __________ Kg x x x 10 5 x 1.00 x x 10 2 x g = 1.57 x 10 2 Kg 157 L = 1.57 x 10 5 mL mL = 1.57 x 10 5 g 157 L = 1.57 x 10 2 Kg

CHAPTER 1LABORATORY CHEMISTRY48 PROBLEM SOLVING n GRAPHING –SCIENTIFIC GRAPHS SHOW THE RELATIONSHIP BETWEEN TWO EXPERIMENTAL VARIABLES n ONE VARIABLE IS CALLED THE INDEPENDENT VARIABLE (THE ONE THAT CHANGES IN THE EXPERIMENT) –PLOTTED ON THE HORIZONTAL (X) AXIS OF THE GRAPH n THE SECOND VARIABLE, CALLED THE DEPENDENT VARIABLE (RESPONDS TO CHANGES IN THE INDEPENDENT VARIABLE)] –PLOTTED ON THE VERTICAL (Y) AXIS OF THE GRAPH

CHAPTER 1LABORATORY CHEMISTRY49 TEMPOCTEMPOC TIME (MIN) DEPENDENT VARIABLE INDEPENDENT VARIABLE FIGURE 1-A TEMP VS TIME EXPERIMENT

CHAPTER 1LABORATORY CHEMISTRY50 PROBLEM SOLVING –LABEL EACH AXIS OF A GRAPH WITH THE NAME OF THE VARIABLE AND THE UNITS OF MEASURE –CONVERT EACH PAIR OF MEASUREMENTS INTO A POINT ON THE GRAPH –CONNECT THE DATA POINTS WITH A “BEST FIT” LINE –TITLE THE GRAPH WHEN IT IS COMPLETE

CHAPTER 1LABORATORY CHEMISTRY51 TEMPOCTEMPOC TIME (MIN) DEPENDENT VARIABLE INDEPENDENT VARIABLE FIGURE 1-A TEMP VS TIME EXPERIMENT

CHAPTER 1LABORATORY CHEMISTRY52 PROBLEM SOLVING COMMON FORMULAS USED IN CHEMISTRY DENSITY = MASS VOLUME VOLUME =LENGTH X WIDTH X HEIGHT CYLINDER VOLUME =  r 2 h PRESSURE = FORCE AREA 1g = 1mL = 1cm 3 o F = 1.8 o C + 32 o C = ( o F-32) K = o C +273 PERCENT ERROR = MEASURED VALUE – ACCEPTED VALUE ACCEPTED VALUE X 100

CHAPTER 1LABORATORY CHEMISTRY53 PROBLEM SOLVING n What is meant by dimensional analysis? n What is a unit equality? A conversion factor? n List and describe the four steps that can be used to solve problems in chemistry.