chem
posted by Anonymous on .
How many pounds does 40.9 in3 of gold weigh? (The density of gold is 19.3 g/cm3, 2.54 cm = 1 in, and 454 g = 1 lb.)
Note these are not large volumesa cup of water is about 30 in3.
So I tried this question and got 34.73, which isn't right. I used this: (1 in)3 = (2.54 cm)3
Path: in3 > cm3 > g > lbs
can someone help please?

Why not show your work and let me find the error? It's easier that way for me to know what went wrong.

okay i just tried it again by doing did (40.9*2.54*19.3)/454 and got 4.42. does that sound right?

No. You didn't cube 2.54.

okay so its 28.49

Yes, but you're only allowed 3 significant figures (from the 19.3 and 40.9) so you should round the answer to 28.5 pounds. I think what your prof wanted you to see was that a cup of gold is quite heavy at almost 30 pounds.

okay thanks!