- #1
Wanting to Learn
This comes from the Intro Homework to my AP Physics 1 class.
The teacher said that it is more important to figure out how to use the website than get the correct answers to the questions. However, I want to know how to get the correct answer, especially since I took chemistry last year and think I should know this.
I'm not certain, but I might just be missing a small step in the calculations.
Problem Statement, Variables and Given Data:
What is the volume V of a sample of 2.70 mol of copper?
The atomic mass of copper (Cu) is 63.5 g/mol.
The density of copper is 8.92×103kg/m3.
Express your answer in cubic centimeters to 3 significant figures.
Attempt at the Solution:
I think I need to multiply and cancel units, however I am not sure what I'm missing.
(I do know how to use the proper number of significant figures.)
2.70mol * 63.5g/mol = 171.45g
8.92×103kg * 1000g/1kg = 8.92 * 106g
(Should I convert the 171.45g to kg here instead?)
*171.45g * 8.92 * 106g/m3 = 1,529,334,000g2/m3
*I am not sure where to go from here in order to get to just meters cubed, assuming that is what I should be looking for.
*update of the two lines above:
I just realized that if I put m3/g then the grams would cancel, and got this:
171.45g * 1m3/8.92 *106g = 0.00001922m3
Now I need to convert that to cm3. I always get confused when doing this, because of the 3. How exactly do I do this last step? I know that I should know this more basic part but I want understand exactly what to do with it.
I tried and the answer I got was one decimal place off; I got 1.92 instead of 19.2cm3.
I did put "volume of 2.70mol Cu" into Wolfram Alpha and got an answer, however I want to know how to get it on my own. Did I miss or do something wrong in the calculations I did, or am I missing something not expressly stated in the question?
Thank you in advance for your help.
The teacher said that it is more important to figure out how to use the website than get the correct answers to the questions. However, I want to know how to get the correct answer, especially since I took chemistry last year and think I should know this.
I'm not certain, but I might just be missing a small step in the calculations.
Problem Statement, Variables and Given Data:
What is the volume V of a sample of 2.70 mol of copper?
The atomic mass of copper (Cu) is 63.5 g/mol.
The density of copper is 8.92×103kg/m3.
Express your answer in cubic centimeters to 3 significant figures.
Attempt at the Solution:
I think I need to multiply and cancel units, however I am not sure what I'm missing.
(I do know how to use the proper number of significant figures.)
2.70mol * 63.5g/mol = 171.45g
8.92×103kg * 1000g/1kg = 8.92 * 106g
(Should I convert the 171.45g to kg here instead?)
*171.45g * 8.92 * 106g/m3 = 1,529,334,000g2/m3
*I am not sure where to go from here in order to get to just meters cubed, assuming that is what I should be looking for.
*update of the two lines above:
I just realized that if I put m3/g then the grams would cancel, and got this:
171.45g * 1m3/8.92 *106g = 0.00001922m3
Now I need to convert that to cm3. I always get confused when doing this, because of the 3. How exactly do I do this last step? I know that I should know this more basic part but I want understand exactly what to do with it.
I tried and the answer I got was one decimal place off; I got 1.92 instead of 19.2cm3.
I did put "volume of 2.70mol Cu" into Wolfram Alpha and got an answer, however I want to know how to get it on my own. Did I miss or do something wrong in the calculations I did, or am I missing something not expressly stated in the question?
Thank you in advance for your help.
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