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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: istrydummy on November 24, 2010, 11:47:17 AM

Title: ***Simple (w/v) calculation. I understand most of it, but the last part....***
Post by: istrydummy on November 24, 2010, 11:47:17 AM

MW sucrose: 342.34 g/mol

So i know that:

1% (w/v) = 1g/100ml

I am given 20%(w/v) of sucrose, which is 20g/100ml.


Now, i have taken 100 microlitres (0.1ml) out of that sucrose solution.

Problem: Find micromoles of total sucrose

My answer: So firstly i converted: 20g/100ml to 2E10^-04g/µL. So if i took 100 µL of sucrose solution, it is just 100 X 2E10^-04g/µL, which is 0.02 g/µL. To turn that into µmoles of sucrose, i did 0.02 g/µL/342.34 = 5.842×10^-5 µmoles.

Can someone tell me where have i gone wrong?

Title: Re: ***Simple (w/v) calculation. I understand most of it, but the last part....***
Post by: DrCMS on November 24, 2010, 11:53:47 AM

0.1ml of a 20%w/v solution contains 0.02g of sucrose

0.02g of sucrose is 0.02/342.34 = 5.84x10^-5 moles.