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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Lt.Pliskin on January 02, 2006, 03:33:36 PM

Title: Calculation of moles EDTA from 2% soln.
Post by: Lt.Pliskin on January 02, 2006, 03:33:36 PM

I am doing a lab and I need to know the amount of moles of EDTA used if I used 40mL of a 2% soln of EDTA. I have tried to come up with an answer, but it just doesnt seem right. Here is my attempt:

40mL EDTA soln. * 0.02 = 0.8mL EDTA used = .8 g EDTA used <--- ( this is where I messed up i believe)

.8g EDTA / (292.24g/mol)  = 2.77*10³ mol EDTA used

If anyone can help, it would be greatly appreciated, I need to get this lab done by tomorrow :-\

Title: Re:Calculation of moles EDTA from 2% soln.
Post by: Borek on January 02, 2006, 04:04:13 PM

Quote from: Lt.Pliskin on January 02, 2006, 03:33:36 PM

.8g EDTA / (292.24g/mol)  = 2.77*10³ mol EDTA used

Check exponent. Everything else seems correct (2% EDTA solution has density of 1.0089 g/mL - but as the concentration is given with 1 SD it doesn't matter).

Title: Re:Calculation of moles EDTA from 2% soln.
Post by: Lt.Pliskin on January 02, 2006, 04:10:45 PM

Oops, I meant an exponent of -3, thanks for confirming my answer, im so glad that I was right ;D . Is the density being ~1 g/mL true with most solns. with a water solvent or is it just specific with EDTA?

Thanks again for the help Borek!

Title: Re:Calculation of moles EDTA from 2% soln.
Post by: Borek on January 02, 2006, 04:27:10 PM

All diluted solutions have density similar to those of pure water - as long as the concentration is below 5% you may safely assume 1.0 g/mL (but not 1.00).