[ink junky]

Hi guys I just made this account, and I'm taking Gen Chem 1 again over the summer as I completely failed it over Spring 2012, numbers and I have never really liked each other, but I am trying.


I have a question from my homework that is just trying to kill my brain hahaha, here goes.

A certain person has a brain that weighs 1.20 kg and contained 1.35x10^10 cells. Assuming that each cell was completely filled with water (density 1.00 g/ml) calculate the length of one side of such a cell if it were a cube.

If the cells were spread out into a layer that was one cell thick, what would be the surface area in square meters?


I divided the 1.20 kg by 1.35x10^10 cells to get 8.88x10^-11 g/cell  and converted that to grams to get 8.88x10^-8 g/ cell.

I just don't know where else to go from there, can some one please help me figure this out, the homework is due tonight, and it is the only questions left.

Edit: I'm not lookinf for just the answers, I would really like for someone to "walk" me through this problem so that I can figure it out, I just don't know where to take it from my last step above. 

[sjb]

Hi guys I just made this account, and I'm taking Gen Chem 1 again over the summer as I completely failed it over Spring 2012, numbers and I have never really liked each other, but I am trying.


I have a question from my homework that is just trying to kill my brain hahaha, here goes.

A certain person has a brain that weighs 1.20 kg and contained 1.35x10^10 cells. Assuming that each cell was completely filled with water (density 1.00 g/ml) calculate the length of one side of such a cell if it were a cube.

If the cells were spread out into a layer that was one cell thick, what would be the surface area in square meters?


I divided the 1.20 kg by 1.35x10^10 cells to get 8.88x10^-11 g/cell  and converted that to grams to get 8.88x10^-8 g/ cell.

I just don't know where else to go from there, can some one please help me figure this out, the homework is due tonight, and it is the only questions left.

Edit: I'm not lookinf for just the answers, I would really like for someone to "walk" me through this problem so that I can figure it out, I just don't know where to take it from my last step above. 

What is the density of water?

[Borek]

8.88x10^-11 g/cell  and converted that to grams to get 8.88x10^-8 g/ cell.

So you are trying to say that 8.88x10^-11 = 8.88x10^-8? No, these numbers are not equal.

[ink junky]

Sorry, I meant to say 8.88x10^-11 kg per cell, and converted it to grams, which came out to 8.88x10^-8 g per cell.

Can anybody help?   Yea I'm a new guy here, but the help would really be appreciated!!!  If my reasoning is wrong please let me know. If you can figure this out, please walk me through the problem, because I would love to be able to work it out own my own. 

8.88x10^-11 g/cell  and converted that to grams to get 8.88x10^-8 g/ cell.

So you are trying to say that 8.88x10^-11 = 8.88x10^-8? No, these numbers are not equal.

[DrCMS]

You have a total weight and are told to use the density of water so you can work out the total volume.
From that total volume and the number of cells you can work out the volume of each cell.
Given the assumption that the cells are a cube you can then work out the length of each side of the cube.

For the 2nd part of the question you can square the side dimension found above and multiple by the number of cells to get the surface area.

[ink junky]

I keep coming to the same thing   

1.20 kg =1200g

did a conversion and get 1200 ml of water,

divided the 1200 ml of water by 1.35x10^10 (number of cells) and came up with 8.88x10^-8 ml of water per cell

converted it to cubic centimeters and I got 8.88x10^-8 cubic centimeters per cell.   After that I don't know what to do.    I know that the volume of a cube is= base x width x height

I just don't know how to take it from the 8.88x10^-8 cubic centimeters per square (assuming that each cell is a cube)   

Am I atleast on the right track?

Haha forgive me if I seem hard headed, but I managed to get 3 As in the spring semester, and then there was chemistry... 

[sjb]

What is the size of a cube that has volume 27cm³?

[ink junky]

What is the size of a cube that has volume 27cm

Well that's too easy, it's 3cm x 3xm x 3 cm = 27 cm³

but 8.88x10^-8 cm<sup>3  


  aaaaaaaah I feel like it's right infront of me, but I just can't seem to figure it out.</sup>

[Borek]

What was the operation you did to find 3 cm?

[ink junky]

What was the operation you did to find 3 cm?

Well for 27 cubic centimeters, the obvious answer is 3x3x3 

for 64 cubic centimeters iths 4x4x4

but I'm still baffeled as to how to get the length of a cube with the volume of 8.88x10^-8 cm³

[DrCMS]

3 is the cube root of 27
4 in the cube root of 64

You need to work out the cube root of 8.88x10^-8

If your calculator does not have a cube root button you can use ^^{0.33333333333}  so 27^{0.33333333333} = 3