<p>1). Wire if often sold in pound spools according to the wire gauge number. That number refers to the diameter of the wire. How many meters are in a ten-pound spool of 12-gauge aluminum wire? A 12-gauge wire has a diameter of 0.0808 in. Aluminum has a density of 2.70 g/cm3 (centimeters cubed).</p>
<p>(kind of understand the general idea, but confused about when to convert and when to keep it in English units. Obviously density is metric....)</p>
<p>2). Oil spreads on water to form a film about 100 nm thick (two sig figs). How many square kilometers of ocean will be covered by the slick formed when one barrel of oil is spilled (1 barrel = 31.5 US gal)?</p>
<p>(NO CLUE AT ALL.)</p>
<p>3). An average adult breathes about 8.50 x 10^3 L of air per day. The concentration of lead in highly polluted urban air is 7.0 x 10^-6 g of lead per one cubed meter of air. Assume that 75% of the lead is present as particles less than 1.0 x 10^-6 m in diameter, and that 50% of the parcicles below that size are retained in the lungs. Calculate the mass of lead absorbed in this manner in one year by average adult living in this environment.</p>
<p>(NO CLUE AT ALL)</p>
<p>On a side note: is AP chem really challenging? I thought I was good at chem because I breezed through it this year...but now that i look at these problems I'm no longer so self-assured. </p>
<p>i have no idea where you got these from, but they sound much more difficult than the problems on the AP, and not related to the major topics the AP covers (equilibrium, acids/bases, redox....)</p>
<p>These are stoichiometry problems. They are representative of AP Chem problems, but the real ones are of a very narrow range of types and you will have done absolutely all of them before you get to the exam. they will require to thought by the time you get to the exam. </p>
<p>1)
convert ten pounds to grams, then use the density to find the volume. then the tricky part: if the length is L, the volume of the wire is pi<em>r^2</em>L. don't forget to convert diameter to radius.</p>
<p>2)
convert one barrel to cubic meters. (google will do it if you type "one barrel in cubic meters"). if it has a surface area of H, then H*100e-9=the number of cubic meters you found from one barrel.</p>
<p>3)
find the amount of air breathed per year. next, multiply by the concentration given to get the total amt of lead. then, you know that fifty percent of seventyfive percent of that much lead is absorbed.</p>
<p>I never saw problems like that in AP Chem. However, the conversions that you do in those problems and the type of math you used to solve them are skills you use in that class a lot. AP chem is a lot of math, so I think what your teacher is going for with those problems is sharpening your math skills. The math in AP chem isn't very complicated, the most you'll have to do is stuff with the quadratic formula, but you do have to put a little more thought into it than just a normal math problem. Once you break the problems down into steps they become pretty easy (see ^), so don't let a long problem with a bunch of units overwhelm you because there will be a lot of them (though no english units thankfully).</p>
<p>^ is completely right about all of the above. English units are a ginormous pain, but even (AP) chemists are pretty lousy about doing metric consistantly. My book was so stuck on kJ that it once wrote 7.3x10^-3 kJ. C'mon...</p>
<p>these are actually our summer work right out of the textbook. x.x</p>
<p>perhaps we use a difference book than everyone else? personally i thought these were pointless problems that will never be applied in real life. but thanks guys everything you said were really helpful!!!</p>
<p>We solved problems like this maybe the first or second day in AP chem. they're factor label/conversion/stoichiometry, but you probably won't come across any problems like that.</p>
<p>People are right in saying that you won't solve a lot of problems like these. Some people are wrong, however, in implying that you won't need the skills from these problems in a typical AP Chemistry problem. Data will constantly be given in different units than the final answer or intermediate calculations, and you will have to solve these types of problems as "side problems" within the actual question.</p>
<p>"My book was so stuck on kJ that it once wrote 7.3x10^-3 kJ. C'mon..."</p>
<p>Some data must be reported in certain units, else they are wrong. Gibbs free energy, for instance, will always be reported in J; it is wrong to say 74 kJ instead of 74 * 10^3 J.</p>