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Unformatted text preview: Course Structure & Assignments CHM 25 Chapter 1 Prof. R.S. Miller Spring, 2009 Lecture: MWF 9:10 – 10 am Homework Homework assignments:12% Weekly Weekly Quizzes (10):10% Hour Hour exams (2): 14% each: February 11th and March 25th February March Final exam (1): 20% Final Clicker Clicker questions Studio: M PM, M eve, T AM, T PM, R AM, R PM Lab Lab reports (14): 30% What is the studio? •Studio is your lab/recitation time – 3 hour time period each week in addition to your MWF lecture time. •You will meet your studio instructor & your TAs for studio this week. •Be prepared to work in the lab this week – dress properly and bring safety goggles. •This is your time to get hands on experience with the topics we cover in lecture. •Lecture and studio are integrated – so it is very important that you take studio time seriously. Studio counts 30% of your final course grade. Studio Studio Attendance Attendance in the studio is mandatory. If you have an athletic event or other activity that requires you to miss your studio session, you must arrange with Dr. Berk in advance of the absence to participate in another studio section. Dr Berk is the general chemistry lab manager her office is Dr. Berk is the general chemistry lab manager – her office is 8Mudd Mudd room 695, email:, phone: 8-3469 If you are ill and miss a studio, contact Dr. Berk within one week of your absence and arrange to make up the absence immediately. Because of the group nature of the work and the role of interactive discussion, it will be extremely difficult to make up a studio once it is over for the week. Why study chemistry? Why (i.e., why are you here?) Health & medicine Prevent & treat diseases How? 1.) Sanitation systems 2.) Surgery w/ anesthesia 3.) Vaccines & antibiotics 4.) Gene therapy a.) genetic diseases b.) impairment of gene(s) Recent advances 1.) Health & medicine 2.) Energy & environment 3.) Materials & technology 4.) Food & agriculture 1 Health & Medicine Huge industry – pharmaceutical 1.) drug design/research 2.) aging – longer & healthier life span Energy & Environment Energy sources (current and future) Energy & Environment Pollution problems Materials & Technology New materials: Polymers (will see in studio this week) Ceramics Liquid crystals (displays) Adhesives Coatings (paints) Examples Food & Agriculture Ag production depends on: 1.) soil 2.) insects/disease 3.) weeds 4.) fertilizers and pesticides Gene research/pesticide/fertilizer research 2 Ag Industry Terminology: Substance – definite composition & distinct properties. Ex. H2O, Ag, NH3 Mixture – 2 or more substances combined physically– physically– each substance retains individual identity. Ex. Cement, milk, soda Element – substance can’t be separated into substance can be separated into simpler simpler substances by chemical means. Periodic table = 118 Compound – substance w/ 2 or more atoms chemically united in fixed composition. 12 million known. Ex. H2O, NH3 States of matter – solid, liquid, gas Chemical Elements • Pure substances that cannot be decomposed by ordinary means to other substances. Aluminum Sodium Bromine Atoms Chemical Compounds Chemical compounds are substances comprised of two or more elements joined together. They can be decomposed back to decomposed back to their their elements, though this is hard to do with most compounds. An atom is the smallest particle of an element that has the chemical properties of the element. Copper atoms on a silica surface. Distance across = 1.8 nanometer (1.8 x 10-9 m) The gemstone aquamarine is composed of the elements aluminum, silicon and oxygen. 3 Elements form Compounds Molecules Molecules are the smallest entity having the same proportions of the constituent atoms as does the compound as a whole. This can be few atoms or thousands of This can be a few atoms or thousands of atoms. atoms. F F F C F C F F F n F C C Tetrafluoroethylene Polytetrafluoroethylene (Teflon or PTFE) Microscopic view of matter: Ways to represent arrangement of atoms in molecules: Substances vs. Mixtures Substances: Substances: The composition and properties are uniform throughout the sample and from one sample to the next. elements elements & compounds fall here Separating Mixtures Mixtures: Mixtures: The composition and properties can vary throughout the sample and/or from one sample to the next. Homogeneous Homogeneous mixtures or a solution Heterogeneous Heterogeneous mixtures 4 States of Matter Properties of matter Chemical – ability of matter to undergo a change in composition. Physical – property of matter that doesn’t change w/ composition. Intensive – independent of amount – density, temperature. Extensive – dependent on amount – mass, volume Physical Changes Physical changes, such as melting points, allow us to distinguish between two compounds. In the studio we will consider how pure materials behave in phase changes compared to mixtures. Chemical Properties The ability or inability of a sample of matter to undergo a change in composition under stated conditions. Chemical Chemical Reaction (Change) occurs when one or more kinds of matter are converted to new or more kinds of matter are converted to new kinds kinds of matter with different compositions. Properties of Teflon Physical Properties: Can be Qualitative or Quantitative Colorless Powdery Solid MP- 342°C Density Density (2.2 g/cm3) Slippery Moldable Insoluble in most solvents Chemical Properties Inert to almost every known chemical including strong acids and bases. Properties of two substances Sugar (sucrose) (sucrose) white crystalline m pt = 185-186oC 18520oC 1.8 g/1 mL H2O at Salt (NaCl) (NaCl) white crystalline m pt = 801oC 0.36 g/1 mL H2O at 20oC 5 Polymers Many ‘mers’ Studio 1 - Identification and separation of polymers by their densities A polymer is a very large molecule (typically either a very long chain or a network) with a very high molecular weight (>10 (>10,000 g/mol). g/mol) Polymers are made from small molecules called monomers. In Studio POLYMERS = MACROMOLECULES … behave differently than matter made of small molecules (POLYMER = MANY “mers”) MANY mers HOW DO YOU CHARACTERIZE THEM? We will use relative densities to identify polymers and separate a polymer mixture. Separating Mixtures – a Physical Process (a) sand/water mixture – heterogeneous – separate by filtration. (b) homogeneous mixture – (li separate by distillation (liquids). di (c & d) homogeneous mixture – separate by chromatography. Simple Simple Distillation apparatus Plot of temperature vs. volume of distillate collected during the distillation of water. 6 Density an important and useful physical property Density = mass (g) volume (cm 3 ) Uncertainties in scientific measurements Systematic errors. Thermometer Thermometer constantly 2 C too low. Mass and volume are extensive properties Density is an intensive property Mercury Platinum Random errors Limitation in reading scale Limitation in reading a scale. Precision Reproducibility Reproducibility of a measurement. Accuracy How How close to the real value. 13.6 g/cm3 21.5 g/cm3 Accuracy vs. precision For you to review in Chapter 1: Scientific method Unit conversions (metric/English) Metric prefixes Density in calculations Density in calculations Significant figures Scientific notation 7 ...
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