Week Two Lecture Notes
Week Two Lecture Notes Chem 105
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This 2 page Class Notes was uploaded by Marisa Loken on Monday September 14, 2015. The Class Notes belongs to Chem 105 at University of Wisconsin - Stevens Point taught by Dr. Riha in Fall 2015. Since its upload, it has received 16 views. For similar materials see Fundamental Chemistry in Chemistry at University of Wisconsin - Stevens Point.
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Date Created: 09/14/15
Week Two Notes September 911 2015 Wednesday September 9 Scienti c method Ask questions observationcollect information form hypothesis experiment recordanalyze data supportsdoesn39t support share Example 0 Observation Miners for manganese and Parkinson39s sufferers had similar symptoms 0 Hypothesis General explanation Similar cause for symptoms 0 Experiments looked at the brain chemistry of miners 0 Observation led to conclusion that there were low dopamine levels in the brain of miners and Parkinson39s disease sufferers 0 Re ne Hypothesis low dopamine levels lead to muscle tremors Parkinson39s Measurements and Uncertainty Metric system Derived units 0 Check tables 14 and 15 in the book 0 Volume is derived from length Volume of cube length cubed 0 Density is derived from mass and volume 0 Density mass divided by volume 0 Kil micro nano milli lnexact quantity Quantity with uncertainty 0 All measured quantities are uncertain Accuracy Refers to how close the measured value is to the true value The more decimal places the more accurate Precision How close multiple measurements are How many digits should I report Instruments with graduations 0 Only report one digit past the smallest graduation Only one estimated digit 0 Example thermometer between 2530 degreespick 27 Signi cant Figures All nonzero digits are signi cant Zeros between nonzero digits are signi cant Zeros at the beginning of a number are never signi cant Zeros at the end of the number are signi cant if there is a decimal In Calculations AdditionSubtraction 0 Number of decimal places is the same as the value with the least amount of decimal places MultiplicationDivision 0 Number of signi cant gures in calculated value is the same as the value with the least amount of signi cant gures Friday September 11 Dimensional Analysis Units are multiplied together divided into each other and cancelled out Key is using correct conversion factor 0 Fraction whose numerator and denominator are the same quantity expressed in different units Example 125 cm 0 Convert to mm 10mm1cm 125cm x 10mm1cm 125mm Unit we start with cancel units in the denominator Units we want go in the numerator 0 Inches 1 inch 254 cm 0 125cm x 1 inch254cm 492 inches Problem Solving Strategies Analyze 0 Determine what the problem is asking o What chemical concepts are involved 0 Map out the problem Collect and Organize 0 Pull out all the information 0 Example values conversion factors and units 0 Determine what equations to use or which conversion factors Solve 0 Use information and equations to solve for the unknown value Check 0 Does the answer make sense