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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Julie Smith on February 23, 2008, 11:00:51 PM

Title: Quantitative determination of nickel
Post by: Julie Smith on February 23, 2008, 11:00:51 PM

Hi, I'm having some trouble on this problem so any help with it is appreciated.

A 10.0mL sample of an unknown aqueous nickel(II) solution was treated and found to produce 0.0532g of Ni(DMG)2 precipitate. Calculate the percent of nickel in the ore sample.

Ok, so first of all am I supposed to write a balanced equation for this? I know that DMG is dimethylglyoxime so I'm not sure how I would do that. If I do have to balance it somehow, is it just a matter of doing a mole to mole kind of thing with nickel(II) to find the percent?

Thanks.

Title: Re: Quantitative determination of nickel
Post by: JGK on February 25, 2008, 11:32:20 AM

I don't think you need an equation to work this out:

If you know the FW of the Nickel glyoxime , you can calulate the percentage which is nickel and therefore the weight of the nickel in the precipitate.

from that you can calculate the concentration in the original solution.

If you know the amount of ore used to give you the solution you should be able to work out a % on a w/w basis

Title: Re: Quantitative determination of nickel
Post by: AWK on February 25, 2008, 11:44:39 AM

http://en.wikipedia.org/wiki/Dimethylglyoxime

Title: Re: Quantitative determination of nickel
Post by: Julie Smith on February 25, 2008, 05:43:04 PM

Quote from: JGK on February 25, 2008, 11:32:20 AM

If you know the FW of the Nickel glyoxime , you can calulate the percentage which is nickel and therefore the weight of the nickel in the precipitate.

ok so what I would do first is  to find the % of Ni I would go grams of nickel/grams of Ni(DMG)2 x100% . That gives me 33.6% of nickel in the compound. From this, do I go 0.0532g of Ni(DMG)2 x0.336 = 0.0178752g of Ni. Then I would get the moles of nickel to find the Molarity, but then I don't know what to do.

Any help is appreciated.

Title: Re: Quantitative determination of nickel
Post by: JGK on February 26, 2008, 12:13:37 PM

I don't believe you supplied enough information to help you further

How much ore was processed (g/kg) and what volumen of the nickel solution did it produce (10 mL or more)?

you know the g of nickel in 10 mL of solution so if you know the weight of ore processed, you can calculate the % w/w of nickel in the ore.

As i don't know the weight of ore processed and the total nickel solution volume (may or may not be 10 mL), I can't help further.

Title: Re: Quantitative determination of nickel
Post by: Julie Smith on February 26, 2008, 05:48:34 PM

I figured it out. Thanks for the help JGK!