CH110 Foundations of GENERAL, ORGANIC, & BIOCHEMISTRY CHEMEKETA COMMUNITY COLLEGE INSTRUCTOR: Larry Emme

1st Day Stuff Who are you? Are you in the right place? GOB CTV Introduction Privacy waver Course Syllabus & requirements Who am I?

Thinking like a Scientist Prologue P.2 Scientific Method: Thinking like a Scientist

Scientific Method The scientific method is the process used by scientists to explain observations in nature.

Scientific Method The scientific method involves Making Observations Writing a Hypothesis Doing Experiments Proposing a Theory

Features of the Scientific Method Observations Facts obtained by observing and measuring events in nature. Hypothesis A statement that explains the observations. Experiments Procedures that test the hypothesis. Theory A model that describes how the observations occur using experimental results.

Summary of the Scientific Method

Major divisions of Chemistry General Inorganic Analytical Physical Organic Biochemistry Elements besides Carbon Methods of analysis Theory and concepts Carbon based compounds Chemistry of living things

Conversion Calculations Chapter 1: Measurement Units of Measurement Significant Figures Conversion Calculations Density

Measurements in chemistry See Handout Sheet of Units of Measurements

Units of Measurement Metric SI Common Conversions Length Volume Mass meter (m) 1 m = 1.09 yd liter (L) 1 L = 1.06 qt gram (g) 1 kg = 2.2 lb

Matter Weight on earth. Matter has Mass and takes up space. =The stuff things are made of. (Air, water, rocks, etc..) Matter has Mass and takes up space. =The amount of stuff (in g’s) (Bowling Ball > Balloon) Matter: The stuff things are made of. Has Mass and takes up space. Mass: The amount of stuff. Usually measured in grams. Bowling ball has more mass than Weight on earth. Weight on earth. =Pull of Gravity on matter.

How much would you weigh Mass Vs. Weight How much would you weigh on another planet? http://www.exploratorium.edu/ronh/weight/

Scientific notation If a number is larger than 1 Move decimal point X places left to get a number between 1 and 10. 1 2 3 , 0 0 0 , 0 0 0. = 1.23 x 108 The resulting number is multiplied by 10X.

If a number is smaller than 1 Scientific notation If a number is smaller than 1 Move decimal point X places right to get a number between 1 and 10. 0. 0 0 0 0 0 0 1 2 3 = 1.23 x 10-7 The resulting number is multiplied by 10-X.

Examples Write in Scientific Notation: 25 = 8931.5 = 0.000593 = 0.0000004 = 3,210. = 2.5  10 1 8.9315  10 3 5.93  10 - 4 4  10 - 7 3.210  103 Do not press this on your calculator!

Scientific notation 1.44939 × 10-2 = 0.0144939 On Calculator 1.44939 (-) 2 EE ×10 Means ×10 Change Sign

Measured & Exact Numbers from counting or by definition 12 coins per package 12 coins 1 package 1 package 12 coins = 12 coins 1 dozen coins 1 dozen coins 12 coins =

Measured & Exact Numbers Measured Numbers = estimated using a tool All measurements contain some uncertainty. We make errors Tools have limits

Accuracy Precision Consistency How close are we to the true value? Truth How well do our values agree? Consistency

Length of object is between 6.7 and 6.8 Significant figures Length of object is between 6.7 and 6.8 The next digit would be a guess.             If use 6.76 then have error of + 0.01cm

Significant figures Expresses accuracy & precision. You can’t report numbers better than the method used to measure them. 6.76 units = 3 sig figures Certain Digits Uncertain Digit

Significant figures 3 Sig Figs Sig Figs don’t depend on the decimal point. 255 millimeters 25.5 centimeters 2.55 decimeters 0.255 meters 0.0255 decameters 3 Sig Figs

Significant figures: Rules for zeros Leading zeros are not significant. 0.00421 3 sig figs Leading zero Captive zeros are significant. 4012 4 sig figs Captive zero Trailing zeros behind decimal are significant. 114.20 5 sig figs Trailing zero

Significant figures: Rules for zeros 32,000 Are the 0’s significant? 2 sig figs = 3 sig figs = 4 sig figs = 5 sig figs = _ 32,000 or 3.2 x 104 32000 or 3.20 x 104 32000 or 3.200 x 104 32000 or 3.2000 x 104 32000.

Significant figures: Rules for zeros 1025 km 2.00 mg 0.00570 520 Four (Captive zeros are significant) Three (trailing zeros behind decimal are significant) Three (only trailing zero behind decimal is significant, leading zeros are not) Two (No decimal, zero assumed insignif)

1st insignificant digit Rounding Write with 4 Significant Figures: 2.5795035 becomes 2.580 > 5 round up < 5 round down. 1st insignificant digit 34.204221 becomes 34.20

Significant figures and calculations An answer can’t have greater significance than the quantities used to produce it. Example How fast did you run if you went 1.0 km in 3.00 minutes? 0.3333333333 speed = 1.0 km 3.00 min = ?

Simplified rules for significant figures Multiplication & Division Problems: Do calculations. speed = 1.0 km 3.00 min = 0.333333333 km min Look at sig figs for each value in calculation. (Constants don’t count.) 3 sig figs 2 sig figs Report answer with same sig figs as least significant value. = 0.33 km min Round off as needed.

Simplified rules for significant figures Addition & Subtraction Problems: Do calculations. Significant to .1 1.9 + 18.65 20.55 Significant to .01 Look at least significant place for each value in calculation. Report answer to least significant place. = 20.6 Round off as needed. Significant to .1

Metric prefixes Prefix Symbol Factor (multiple) Changing the prefix alters the size of a unit. Prefix Symbol Factor (multiple) mega M 106 1,000,000 kilo k 103 1,000 deci d 10-1 0.1 centi c 10-2 0.01 milli m 10-3 0.001 100 1

Problem Solving Using Conversion Factors Many problems require a change of one unit to another unit by using conversion factors (fractions). unit1 × conversion factor = unit2

How many feet are there in 22.5 inches? The conversion factor must accomplish two things: unit1 × conversion factor = unit2 inches × conversion factor = feet It must cancel inches. It must introduce feet

The conversion factor takes a fractional form.

Putting in the measured value and the ratio of feet to inches produces:

Convert 3.7×1015 inches to miles. Inches can be converted to miles by writing down conversion factors in succession. in  ft  miles

Convert 4.51030 cm to kilometers. Centimeters can be converted to kilometers by writing down conversion factors in succession. cm  m  km

Conversion of units Examples: 10.7 T = ? fl oz 62.04 mi = ? in 5 kg = ? mg 9.3 ft = ? cm 5.7 g/ml = ? lbs/qt

Density Density = g At 4 o C Mass Volume g cm3 ml 1cc = 1 cm3 = 1 ml = 1 g water g cm3 g ml At 4 o C or Water 1.0 Urine 1.01 - 1.03 Air 0.0013 Bone 1.7 - 2.0 Gold 19.3 Oil 0.8 - 0.9

d = m V V = m d m = V d d = 5.230 g 5.00 ml Density calculation What is the density of 5.00 ml of serum if it has a mass of 5.230 g? d = m V V = m d m = V d d = 5.230 g 5.00 ml = 1.05 g ml

Specific Gravity is unitless. density of substance g ml Specific Gravity = density of reference g ml Reference commonly water at 4oC Specific Gravity is unitless. At 4oC, density = specific gravity.

Commonly used to test sugar in urine. based on Specific Gravity. Hydrometer Commonly used to test sugar in urine. Float height will be based on Specific Gravity.

Density as a Conversion A liquid sample with a density of 1.09 g/mL is found to weigh 7.453 grams. What is the volume of the liquid in mLs? Identify any conversion factors. What is unique to the problem? 7.453 g 1.0 ml 1.09 g = ml 6.837614 = 6.84 ml How should the answer look? 1.09 g 1 ml 1 ml 1.09 g