Asked by Grace

2. Perform this operation and report the answer to the correct number of significant figures: What is the mass of a cube of aluminum that is 4.0 cm on each edge? The density of aluminum is 2.7 g/cm^3. Show all calculations leading to an answer.
(I think I solved this correctly but I would like to check, also I am not quite sure what it means by "the correct number of significant digits" what do they consider the correct number?)

Vcube = length*width*height
Vcube = 4.0cm*4.0cm*4.0cm
Vcube = 36cm^3
2.7g/cm^3 = m/36cm^3
m = 2.7g/cm^3*36cm^3
m = 97.2g
Answered by bobpursley
two errors.
4*4*4 is NOT 36

the answer should be only to two sig figures.
Answered by Grace
Vcube = length*width*height
Vcube = 4.0cm*4.0cm*4.0cm
Vcube = 64cm^3
2.7g/cm^3 = m/64cm^3
m = 2.7g/cm^3*64cm^3
m = 172g
is this better?
Answered by DrBob222
Your 64 cc is now right but you reported the mass to three places. You're allowed only two because you have two in 2.7 g/cc.
Here is a link about significant figures.
http://www.chemteam.info/SigFigs/SigFigs.html
That means your 172 (I obtained 172.8 which rounds to 173 to three places) answer should be rounded and displayed as 1.7E2.
Answered by Grace
Thank you!
Answered by Liz
What is the "E2" at the end of your answer? @DrBob222
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