Unformatted text preview: 9/23/11 Basic Informa�on Chemistry 101 Professor Frank A. Gomez
Professional behavior. Cell phones on vibrate. NO CHEATING on exams. No plagiarism in lab reports or homework. Arrive on �me to class. No make up exams. Chemistry 101 Wing B E 122 323-‐343-‐2368 Oﬃce hours: MW 10:40 AM – 12:40 PM [email protected] Website: h�p://www.calstatela.edu/dept/chem/class-‐
notes.htm Chemistry 101
Why are we here? What is chemistry? Why is chemistry so important to us? What do you want to learn over the next 10 weeks? How is this course going to improve your general knowledge? Your well-‐being? Your life? Chemistry 101 Engineering Biology Medicine Chemistry Geology Materials Physics Science 1 9/23/11 Problem Solving Problem Solving Understand a problem before you try to work it. Learn to recognize the type of problem. If you do not understand some words or terms in the problems, look up their meaning in the text or a dic�onary. Do not guess. In problems that involve many words or a descrip�ve situa�on, rewrite the problem using a minimum number of words to express the bare-‐bones essence of the problem. Some problems give more informa�on than is needed for the situa�on. Learn to pick out what is needed and ignore the rest. When appropriate, draw a simple sketch of diagram (with labels) to show how diﬀerent parts are related. Speciﬁcally pick out what is given and what is asked for. Problem Solving Problem Solving Look for a rela�onship between what is given and what is asked for. Set up the problem in a concise, logical, stepwise manner, using units for all terms and factors. Do not try to bend all problems into a mindless “propor�on” approach that you have mastered in elementary grades; this appeals to intui�on, not logic. Its use is a hindrance to intellectual progress in science. Think about your answer. Remember UNITS and whether it is reasonable in size for the informa�on given. If not, check back and see if you can locate the trouble. Basic Molecular Nature of Chemistry Basic Molecular Nature of Chemistry The fundamental unit of a chemical substance is the atom and is derived from the Greek atomos meaning “uncu�able”. Diameter of a carbon atom is 3 angstroms. A molecule is a combina�on of two or more atoms held together in a speciﬁc shape by a�rac�ve forces. The simplest molecules contain two atoms (H2). 2 9/23/11 Basic Molecular Nature of Chemistry Scales of measurement. Characteris�cs of Ma�er Ma�er is anything that has mass and occupies space. It can be made up of only one substance or any number of diﬀerent substances. Ma�er can be categorized according to shape and volume. Phases are solid, liquid and gas. Ma�er Transforma�ons of Ma�er Flowchart showing how to classify a sample of ma�er. A transforma�on is any process that changes the proper�es of a substance. In a physical transforma�on, physical proper�es change, but the substance’s chemical nature remains the same. Transforma�ons of Ma�er Transforma�ons of Ma�er A chemical transforma�on produces new chemical substances. A chemical transforma�on produces new chemical substances. 3 9/23/11 Transforma�ons of Ma�er A chemical transforma�on produces new chemical substances. Signiﬁcant Digits When adding or subtrac�ng, the number of decimal places in the result is the number of decimal places in the number with the fewest places. 0.0120 1.6 8.49026 4 decimal places 1 decimal place 5 decimal places 3 sig ﬁgures 2 sig ﬁgures 6 sig ﬁgures 10.1 1 decimal place 3 sig ﬁgures The value with the fewest decimal places determines the number of decimal places in a sum. Scien�ﬁc Nota�on Signiﬁcant Digits When mul�plying or dividing, the number of signiﬁcant ﬁgures in the result is the same as the quan�ty with the fewest signiﬁcant ﬁgures. (0.0120)(1.6)(8.49026) = (0.16) Sig ﬁg 3 2 6 2 Dec place(s) 4 1 5 2
3.196 + 0.0825 +12.32 + 0.0013 = 721.56 – 0.394 = 525.3 + 326.0 + 127.12 + 330.0 = (3.21) (432) (650) / 563 = The mul�plier with the fewest signiﬁcant ﬁgures determines the number of signiﬁcant ﬁgures in a product. Problem 1 Problem 2 A farmer owns a rectangular ﬁeld that fronts along a Cu has a density of 8.94 g/cm3. If a factory has an ingot of Cu that has a mass of 125 lb and the ingot is drawn into wire with a diameter of 9.50 mm, how many feet of wire can be produced? road. State highway engineers surveyed the frontage and found that it measures 138.3 m in length. The farmer, who wants to build a fence around the ﬁeld, paces oﬀ the ﬁeld’s width and es�mates it to be 52 m. How many meters of fences will the farmer have to build? What mass of fer�lizer will the farmer need to fer�lize the ﬁeld with 0.0050 kg of fer�lizer for each square meter of ﬁeld? 4 9/23/11 Problem 3 Problem 4 An ancient Au coin is 2.2 cm in diameter and 3.0 mm thick. It is a cylinder for which volume = πr2h. If the ρ of Au is 19.3 g/cm3, what is the mass of the coin in g? Assume a price of Au of $1288 per troy ounce. How much is the coin worth? (1 troy ounce = 31.10 g) About two centuries ago, Benjamin Franklin showed that 1 tsp of oil covers about 0.5 acre of s�ll water. If you know that 1.0 X 104 m2 = 2.47 acres and that there are approximately 5 cm3 in a teaspoon, what is the thickness of the layer of oil? How might this thickness be related to the sizes of molecules? Problem 5 Problem 6 CO is a common pollutant in urban environments. On one par�cular day the air contained 5.5 mg of CO per 1.000 m3 of air. On that day, how many grams of CO were present in a room that had the dimensions 12’ X 9.5’ X 10.5’? An empty 3.00 L bo�le weights 1.70 kg. Filled with a certain wine it weights 4.55 kg. The wine contains 11.0% ethyl alcohol by mass. How many ounces of ethyl alcohol are present in a 400 mL glass of this wine? (1 lb = 16 oz = 453.6 g) Problem 7 CCl4 and H20 do not dissolve in each other. When mixed, they form two separate layers. CCl4 has a density of 13.3 lb/gal and H20 has a density of 62.4 lb/�3. Which liquid will ﬂoat on top of the other when the two are mixed? 5 ...
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