Calculating Glucose Concentration of Solution

[MichaelXY]

[SOLVED] Percent of solution

Homework Statement

Let's say we have 5% glucose of a 10 mL solution. So that would imply that .5 mL of the solution is glucose, but that does not really tell me how much glucose. Is it assumed that the glucose is 1 molar?

I ask because in one of my bio labs we did a lab where we were given exactly as stated above. Knowing the exact amount of glucose was not needed for the lab, however, I would like to understand this for future use.

Thanks for any input.

 

[amd123]

http://chemistry.about.com/od/lecturenotesl3/a/concentration.htm that should help, basically what you do is use the molarity = moles per 1 liter over liters

 

[UMich1344]

Yeah, the post above mine tells you exactly what you need to do.

 

[MichaelXY]

Okay, let's see if I got this right. Since the solute is H2O, I assume 1 molar H2O.
Since 1 mole H2O = 18 grams/mole and I use the molarity formula to get grams.
10mL of H20 or .01L x 1 molar = .01 grams of H20.
ergo .01g H2O x 5% = 5 x 10^-4 gram glucose, or .0005 gram.
Is that correct?

Thanks in advance

 

[amd123]

yes now if only someone would help me for christ's sake...

 

[MichaelXY]

I wish I could, but as you can see, I am not that good at chem. Thanks for the assist :)

 

[symbolipoint]

You probably need to use units of percent weight/volume of solution. The glucose solution is not sensibly prepared as volume of glucose solid per volume of solution.

 

[MichaelXY]

So by that you mean, Mass of solute/100 mL solution? So I think that would equate to .5 gram C6H12O6 @ 10mL Does that sound correct?

 

[symbolipoint]

So by that you mean, Mass of solute/100 mL solution? So I think that would equate to .5 gram C6H12O6 @ 10mL Does that sound correct?

That would give you 5 percent weight per volume.