Welcome to the World of Chemistry Yale University Chemistry 113 Chemistry 113 Chemistry 113 Lectures: Prof. Victor S. Batista Discussions: Dr. Iona Black Ms. Brooke Rosenzweig Mr. Robert Snoeberger

REGISTRATION Chem 113 students have to register their preferences for a discussion section online as well as in the hard copy card distributed during the first lecture.online Students will be able to register their section or lab preference (1, 2, 3) online by following instructions at the Online Course Information (OCI) website. Preference selection has opened and will close on Friday, Sept. 7 at 12:30 PM. At that time each instructor will be able to assign students according to their preferences for sections. The office staff will upload the section assignments to the Online Course System (OCS) and students will be able to see their section on their course registration sheet.

Where’s the Syllabus ?

What does Chemistry concern with ? Chemistry is the foundation of all molecular sciences Chemistry provides understanding, prediction and control of the nature and behavior of matter Chemistry is practical and profoundly philosophical HOW CAN SUBSTANCES BE MADE ? HOW DOES MATTER REACT ?! WHAT MATTER IS ?!!

Chemistry & Matter Chemistry explores the MACROSCOPIC world — what we can see —Chemistry explores the MACROSCOPIC world — what we can see — to understand the PARTICULATE world we cannot see.to understand the PARTICULATE world we cannot see. EXPERIMENTS provide insights into these worlds beyond what our eyes can actually see!! EXPERIMENTS provide insights into these worlds beyond what our eyes can actually see!! Chem 113 students are strongly encourage to take the lab Chem 116L

Chemistry 116LFall 2007 Register in Chem 116L online through the OCSonline through the OCS Placement list will be available online on September 7. Purchase a copy of the lab manual from TYCO (corner of Elm & Broadway), and study the first ten pages. Next week we have orientation and Ex. 1. at 1 pm (for both the 12 noon and 1 pm sections). Everyone should try to attend the orientation on the day they are placed in Chemistry 116L. Wear shoes ! Any questions? Need additional info? Dr. G:

A Chemist’s View: Exp. I 2 H 2 (g) + O 2 (g) --> 2 H 2 O(g) MacroscopicMacroscopic SymbolicSymbolic ParticulateParticulate

Chemical Properties and Chemical Change Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules. Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.

Scientific Method (1) OBSERVE AND QUESTION about some aspect of the world.(1) OBSERVE AND QUESTION about some aspect of the world. (2) POSTULATE a tentative explanation (HYPOTHESIS) and(2) POSTULATE a tentative explanation (HYPOTHESIS) and make predictions. make predictions. (3) TEST those predictions against(3) TEST those predictions against observations of reproducible events. observations of reproducible events. (4) REPEAT steps 2 and 3 until there are no more discrepancies between predictions and observations.(4) REPEAT steps 2 and 3 until there are no more discrepancies between predictions and observations. When consistency is obtained, hypotheses become a theory (i.e., a coherent set of propositions that explain a wide class of phenomena. When consistency is obtained, hypotheses become a theory (i.e., a coherent set of propositions that explain a wide class of phenomena.

Types of Observations and Measurements We make QUALITATIVE observations of reactions — changes in color and physical state.We make QUALITATIVE observations of reactions — changes in color and physical state. We also make QUANTITATIVE MEASUREMENTS, which involve numbers.We also make QUANTITATIVE MEASUREMENTS, which involve numbers. Use SI units — based on the metric systemUse SI units — based on the metric system

UNITS OF MEASUREMENT Use SI units — based on the metric system LengthMassTimeTemperature Meter, m Kilogram, kg Seconds, s Celsius degrees, ˚C kelvins, K kelvins, K

Units of Length 1 kilometer (km) = ? meters (m)1 kilometer (km) = ? meters (m) 1 meter (m) = ? centimeters (cm)1 meter (m) = ? centimeters (cm) 1 centimeter (cm) = ? millimeter (mm)1 centimeter (cm) = ? millimeter (mm) 1 nanometer (nm) = 1.0 x meter1 nanometer (nm) = 1.0 x meter 1 angstrom (A) = 1.0 x meter1 angstrom (A) = 1.0 x meter O—H distance = 9.4 x m 9.4 x cm nm A O—H distance = 9.4 x m 9.4 x cm nm A o o

Temperature Scales FahrenheitFahrenheit CelsiusCelsius KelvinKelvin Anders Celsius Lord Kelvin (William Thomson)

Temperature Scales 1 K degree = 1 degree Celsius Notice that 1 K degree = 1 degree Celsius Boiling point of water Freezing point of water Celsius 100 ˚C 0˚C 100˚C Kelvin 373 K 273 K 100 K Fahrenheit 32˚F 212 ˚F 180˚F

Temperature Scales 100 o F = 38 o C = 311 K oFoF oCoC K 38 o C = (100 o F – 32 o F) * 100 o C / 180 o F 311 K = 273 K + 38 o C * 100 K / 100 o C Conversion Factor: o C o F 100 o C degrees per 180 o F degrees 32 o F = 0 o C = 273 K 32 o F = 0 o C = 273 K

Calculations Using Temperature Generally require temp’s in kelvinsGenerally require temp’s in kelvins T (K) = t (˚C) T (K) = t (˚C) Body temp = 37 ˚C = 310 KBody temp = 37 ˚C = 310 K Liquid nitrogen = -196 ˚C = 77 KLiquid nitrogen = -196 ˚C = 77 K Generally require temp’s in kelvinsGenerally require temp’s in kelvins T (K) = t (˚C) T (K) = t (˚C) Body temp = 37 ˚C = 310 KBody temp = 37 ˚C = 310 K Liquid nitrogen = -196 ˚C = 77 KLiquid nitrogen = -196 ˚C = 77 K

Physical Properties What are some physical properties? colorcolor melting and boiling pointmelting and boiling point odorodor Physical properties characterize the identity of pure substances salt sodium

Physical Changes Some physical changes would be boiling of a liquidboiling of a liquid melting of a solidmelting of a solid dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION. Physical changes do not change the identity of Pure Substances

DENSITY - an important and useful physical property Mercury 13.6 g/cm g/cm 3 Aluminum 2.7 g/cm 3 Platinum Physical properties, cont’d

Problem A piece of copper has a mass of g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm 3 ). Density  mass(g) volume(cm 3 )

Strategy 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density.

SOLUTION 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density. (9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm 3 Note only 2 significant figures in the answer! Conversion factor Significant Figures ??!!! # of digits, starting from the left, with the first digit different from zero. (‘Trailing’ zeros don’t count)

Significant Figures g 4 significant figures 7.23 cm 3 significant figures 0.95 mm 2 significant figures cm 2 significant figures (zeros to the left of 9 simply locate the decimal point) 600. g 3 significant figure 8000 kg 1 significant figure 100 cm/m infinte number of significant figures (defined quantity)

DENSITYDENSITY Density is an INTENSIVE property of matter.Density is an INTENSIVE property of matter. –does NOT depend on quantity of matter. –temperature Contrast with EXTENSIVEContrast with EXTENSIVE –depends on quantity of matter. –mass and volume. Styrofoam Brick

INVERSE PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 mL of Hg in grams? In pounds? Solve the problem using DIMENSIONAL ANALYSIS.

Strategy 1.Use density to calc. mass (g) from volume. 2.Convert mass (g) to mass (lb) Need to know conversion factor = 454 g / 1 lb PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 mL of Hg? First, note that 1 cm 3 = 1 mL

1.Convert volume to mass PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 mL of Hg? 2.Convert mass (g) to mass (lb) Inverse Problems