Chemists and Chemistry Lecture 1 郭修伯

General chemistry Text book: –“Chemical Principles”, Steven, S. Zumdahl, 6 th Edition, 2009, Houghton Mifflin Co., NY. ( 歐亞書局 ) Grade: –Quiz and Homework: 20% –Mid-Term Exams: 25% x 2 = 50% –Final Exam: 30%

Typical chemists interact with a great variety of other people while doing their jobs

Various parts of scientific method A law summarizes what happens; a theory (model) is an attempt to explain why it happens.

Industrial chemistry Industrial processes require large plants for production of chemicals.

Chemical industry The isolation of natural occurring substances for use as raw materials. The processing of raw materials by chemical reactions to manufacture commercial products. The use of chemicals to provide services.

Chemical eng. & chemistry (I) Laboratory: –Practicality is typically the most important consideration. –Small amount substance –Hazardous materials are handled using fume hoods, safety shields and so on Industry: –Economy and safety are critical

Chemical eng. & chemistry (II) Laboratory: –By-products are disposed of –Batch process run at (relatively) low T and P Industry: –Containers and pipes are metal and corrosion is a constant problem –Cannot monitored visually, gauges are used –By-products are recycled or sold (may need to create one market!) –Continuous processes run at high T and P

Typical chemical process A need for particular product is identified Relevant chemistry is studied in a lab: –various ways of production are evaluated in terms of costs and potential hazards Evaluations between chemists, chemical engineers, business managers, safety engineering and others Pilot-plant test –make sure the reaction is sufficient at a larger scale –test reactor design –determine the costs of the process –evaluate the hazards –gather information on environmental impact

Polymer: Real-World Chemistry Over 50% for all industrial chemists have jobs that are directly related to polymers –Polyvinyl Chloride (PVC) ： –Made from molecule commonly called vinyl chloride n usually > 1000

PVC High-volume plastic: ~10 billion pounds per year in US Pure PVC: hard, brittle, decompose easily at high temperatures Discovered by German chemical company in 1912 (patent ~1926) Additives addition: rigid or highly flexible ca. 100 different plasticizers (softeners) for PVC Half of the annual US production of PVC is formed into piping

PVC additives Softeners: –Ex: phosphate and phthalate esters Thermal stabilizers: –Ex: mixture of antimony ( 銻 ) and calcium salts UV absorber –Protect against damage from sunlights –TiO 2 is usually used Fire retardants –White antimony oxide (Sb 2 O 3 ) is usually used –For transparent PVC: sodium antimonate (Na 3 SbO 4 ) is usually used

PVC products Product production: –Additives + PVC powders are blended (dry- blending) –Mixtures are melted and formed into pellets –Pellets are shipped, remelted and formed into the desired products Considerations: –Effectiveness of the products, cost, ease of production, safety and environmental impact –Waste disposal? Recycling?