THE SCIENTIFIC METHOD A SYSTEMATIC APPROACH A WAY OF ANSWERING QUESTIONS AND/OR SOLVING PROBLEMS STEPS OF THE SCIENTIFIC METHOD OBSERVATION LEADS TO A QUESTION OR DISCOVERS A PROBLEM RESEARCH (OBSERVATION, LIBRARY, OTHER) HYPOTHESIS A TENTATIVE ANSWER TO THE QUESTION EXPERIMENT SCRUPULOUS RECORD KEEPING ANALYZE DATA CONCLUSION BASED ON THE EXPERIMENTAL DATA REPEAT EXPERIMENTATION CHAPTER 1 LABORATORY CHEMISTRY

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

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

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

UNITS OF MEASURE 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 1 LABORATORY CHEMISTRY

UNITS OF MEASURE SI BASE UNITS mass kilogram kg length meter m PHYSICAL QUANTITY UNIT NAME SYMBOL mass kilogram kg length meter m time second s count, quantity mole mol temperature kelvin K electric current ampere A luminous intensity candela cd CHAPTER 1 LABORATORY CHEMISTRY

UNITS OF MEASURE 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 ! LENGTH (m) x WIDTH (m) AREA (m2) = CHAPTER 1 LABORATORY CHEMISTRY

UNITS OF MEASURE DERIVED UNITS USED IN SCIENCE area square meter m2 PHYSICAL QUANTITY UNIT NAME SYMBOL area square meter m2 volume cubic meter m3 force newton N pressure pascal Pa energy joule J power watt W voltage volt V frequency hertz Hz electric charge coulomb C CHAPTER 1 LABORATORY CHEMISTRY

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

UNITS OF MEASURE NON-SI UNITS USED IN SCIENCE volume liter L PHYSICAL QUANTITY UNIT NAME SYMBOL volume liter L pressure atmosphere atm millimeters of mercury mmHg temperature Celsius degree Co energy calories cal CHAPTER 1 LABORATORY CHEMISTRY

UNITS OF MEASURE 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 1 LABORATORY CHEMISTRY

UNITS OF MEASURE COMMON PREFIXES PREFIX ABBREVIATION VALUE SCI. NOTATION Giga- G 1 000 000 000 109 mega- M 1 000 000 106 kilo- k 1 000 103 hecto- h 100 102 deka- D (Dk) 10 101 ROOT UNIT meter, liter, gram 1 100 deci- d 0.1 10-1 centi- c 0.01 10-2 milli- m 0.001 10-3 micro-  0.000 001 10-6 nano- n 0.000 000 001 10-9 pico- p 0.000 000 000 001 10-12 CHAPTER 1 LABORATORY CHEMISTRY

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

UNCERTAINTY IN MEASUREMENT 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: 1. MEASURING INSTRUMENTS ARE NEVER COMPLETELY FREE OF FLAWS. 2. MEASURING ALWAYS INVOLVES SOME ESTIMATION. CHAPTER 1 LABORATORY CHEMISTRY

UNCERTAINTY IN MEASUREMENT ESTIMATING WITH A SCALE MINISCUS 23  1 30 30 25 25 20 20 15 15 10 10 5 5 CHAPTER 1 LABORATORY CHEMISTRY

UNCERTAINTY IN MEASUREMENT RELIABILITY IN MEASUREMENT THERE ARE TWO WAYS TO CHECK RELIABILITY PRECISION: REPEAT THE MEASUREMENT SEVERAL TIMES….A RELIABLE MEASUREMENT WILL GIVE ABOUT THE SAME RESULT AGAIN AND AGAIN. 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 1 LABORATORY CHEMISTRY

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

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

WORKING WITH NUMBERS SCIENTIFIC NOTATION CONVERTING NUMBERS TO SCIENTIFIC NOTATION 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. IF THE NUMBER IS LESS THAN 1 THE EXPONENT OF 10 IS NEGATIVE 10-X IF THE NUMBER IS GREATER THAN 1 THE EXPONENT IS POSITIVE 10X CHAPTER 1 LABORATORY CHEMISTRY

WORKING WITH NUMBERS 32,700 3.27 X 104 O.OOO341 3.41 X 10-4 45,500,000 0.0000234 2.34 X 10-5 CHAPTER 1 LABORATORY CHEMISTRY

WORKING WITH NUMBERS 0.0000056 5.6 X 10-6 7,250 7.25 X 103 3.25 X 104 32,500 3.25 X 104 0.002260 2.260 X 10-3 5.939 5.939 X 100 CHAPTER 1 LABORATORY CHEMISTRY

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

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 1 LABORATORY CHEMISTRY

PROBLEM SOLVING: Conversions Convert 234 mL into L. Step 1 Kilo Hecto Deka Standard (m, L,g) deci centi milli You want to go to Liters That’s three steps 3 2 You are at milli- 1 CHAPTER 1 LABORATORY CHEMISTRY