Chemistry Problem help please!?

Question

Here it is: A copper refinery produces a copper ingot weighing 150 lb. If the copper is drawn into wire whose diameter is 8.25 mm, how many feet of copper can be obtained from the ingot? The density of copper is 8.94 g/cm^3.

I know this requires stoichiometry but I don't know how to get from density to the feet of copper! Can someone please help?

Answer 1

Thank you, Paul. for pointing out what chemistry really IS and is NOT all about. I feel that I too must weigh into this inane approach some instructors take in teaching 'chemistry'...even though this may not be the best venue for such a debate.

Any day now, I expect to see a problem stating: "A rectangular pool of water has a diagonal measuring 14.54 rods and depth of 3.194 cables.  If it contains 1.887 picograms of radium per pint, how much radium is in the pool?  Express your answer in ounces per cubic mile."

Who cares? What has this to do with chemistry? This should be relegated (if at all) to the MATH section, not CHEM. IMNSHO, students struggling to learn chemistry, a difficult subject in its own right, should not be frustrated by such assinities. I am certain that this nonsense is driving some potentially brilliant chemists from our field.

REAL chem 'railroad problems' can be difficult to solve, but aspiriing chemists should find them interesting at least...eg "Using acetylene as your only organic compound, how would you synthesize benzaldehyde?"

'addict3d', feel free to print this out and give it to your instructor, to show him/her how professional chemists feel about this subject...if you think that this will cause you no harm ..some cannot handle constructive criticism :-))

Answer 2

Convert lb to g (1 lb = 453.592 g)

Divide by density of copper (g/cm^3) to get volume.

Use A = pi r^2 to get area of wire (care in calculating r! And use cm not mm)

Divide volume by area to get length (cm)

Convert to feet using 1 ft = 30.48 cm

Complain to your teacher that chemistry is supposed to be a fascinating subject, concerned with the reactivity and properties of substances, and not fiddling around with stupid unit conversion problems.