Brewing Benedict's Reagent

[iopiop]

I am trying to create some benedict's solution.

The ingredients:

Copper(II)Sulfate: Created with copper and sulfuric acid.

as described here http://www.scienceforums.net/forum/showthread.php?t=10342

 

ANY metal will not suffice, it has to be Copper.

 

dump the acid from a car battery into a large plastic bowl.

leave it for an hour for the particulate matter to settle, then pour the liquid through a large funnel with a coffee filter in it, into a large jar.

then get some copped pipe offcuts from a plumber, or just any old copper that`s quite thick that nobody wants and use that instead, whatever.

you`ll need a car battery charger, clamp one lead onto one copper peice and the other lead onto another copper peice then put them in you jar that contains the filtered acid.

making 100% sure both copper peices DO NOT touch!, you may turn the power on and leave it for a day or 2.

check every now and then that the electrodes haven`t dissolved.

the liquid will turn Blue

after 2 days disconnect the power, drop the copper electrodes in the jar, put the lid on and leave it for a week.

pour the liquid out after this time into a large based bowl to evaporate the water, the crystals that form will be your copper sulphate

 

Sodium Carbonate:

Help! how should I get this?

 

Sodium Citrate:

Help! how should I get this?

Sodium Citrate dihydrate

 

 

After All Ingredients are gathered

Benedict's Reagent: We generally use a commercial reagent, but to make it from scratch, first dissolve 100 g sodium carbonate and 173 g sodium citrate dihydrate in a final volume of 850 mL water. Slowly, with stirring, add a solution of 17.3 g copper sulfate pentahydrate in 100 mL of water. Bring the final volume to one liter. The commercial reagent, at least, seems to be stable for years.

When 1 mL of reagent is heated with 5 drops of sample in a boiling water bath, a positive test for reducing sugars is formation of a precipitate within five minutes. The color ranges from green to yellow to orange to brick-red depending on the amount of reducing sugar in the sample; with a sample containing 1% glucose, the precipitate is usually brick-red.

 

I found this from searching on the internet. But I am having a little bit of trouble understanding this.

When they say 173 g of "sodium citrate dihydrate" would this include the mass of 2 H2O molecules with each molecule of Sodium citrate dihydrate?

 

and when thay say "17.3 g copper sulfate pentahydrate in 100 mL of water"

is the 100ml of water beyond the 5 water molecules for each molecule of Copper sulfate?

 

(17.3g of Coper Sulfate) + (6 molecules of water for each molecule of coper sulfate) + (an additional 100ml of water)

 

[YT2095]

ignore the water of crystalisation in the CuSO4, it`s Trivial.

 

as for the sodium carbonate you can Buy this as "washing Soda" it`s really cheap as well at most supermarkets, you can bye citric acid at health food shops, home brew winemaking shops also.

 

when you have your citric acid you can dissolve this in water and add washing soda until all fizzing stops and then evaporate the water to leave your sodium citrate.

 

that`s about it really

[iopiop]

Thank you very much.

Do you happen to know the correct chemical equations for the sodium citrate synthesizing method you described?

 

Based on the information I read here:

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

When someone just says "Sodium Citrate" they are talking about "Monosodium citrate" correct?

 

Na2CO3 + C6H8O7 --> NaH2(C3H5O(COO)3)

 

is NaH2(C3H5O(COO)3) the correct molecular formula?

 

Will someone have a peak at this?

http://dmwdev.com/science_cu_sulfate.html

 

Does that large amount of Copper Precipitate mean that all of my Sulfuric Acid has been converted into Copper(II) Sulfate?

Should I take the copper electrodes out now?

Should I filter that copper muck out?

[mskittykat]

To answer your questions, you don't consider the extra water molecules for the copper pentahydrate. The chemical comes as is, you add

17.3 g.

 

I'm about to make this, so here is my instructions:

Weigh out 100g sodium carbonate, 173g sodium citrate, 17.3g copper sulfate pentahydrate.

Fill up a flask/beaker with ~800mL distilled water.

Dump the powders in there and stir until dissolved

Take your solution and pour into a grad cylinder and top with DI water until 1L

 

You don't have to be precise with the water, depends what you're doing with the solution.

 

To answer other people's questions, you can buy these chemicals at Sigma Aldrich or Alfa Aesar (cheapest

place I've seen), I don't know though if they just sell to residential areas, depends on the restrictions in your

area.

 

 

 

 

 

I am trying to create some benedict's solution.

The ingredients:

Copper(II)Sulfate: Created with copper and sulfuric acid.

as described here http://www.sciencefo...ead.php?t=10342

 

 

 

Sodium Carbonate:

Help! how should I get this?

 

Sodium Citrate:

Help! how should I get this?

Sodium Citrate dihydrate

 

 

After All Ingredients are gathered

 

 

I found this from searching on the internet. But I am having a little bit of trouble understanding this.

When they say 173 g of "sodium citrate dihydrate" would this include the mass of 2 H2O molecules with each molecule of Sodium citrate dihydrate?

 

and when thay say "17.3 g copper sulfate pentahydrate in 100 mL of water"

is the 100ml of water beyond the 5 water molecules for each molecule of Copper sulfate?

 

(17.3g of Coper Sulfate) + (6 molecules of water for each molecule of coper sulfate) + (an additional 100ml of water)

 

[pippo]

I am trying to create some benedict's solution.

The ingredients:

Copper(II)Sulfate: Created with copper and sulfuric acid.

as described here http://www.scienceforums.net/forum/showthread.php?t=10342

 

 

 

Sodium Carbonate:

Help! how should I get this?

 

Sodium Citrate:

Help! how should I get this?

Sodium Citrate dihydrate

 

 

After All Ingredients are gathered

 

 

I found this from searching on the internet. But I am having a little bit of trouble understanding this.

When they say 173 g of "sodium citrate dihydrate" would this include the mass of 2 H2O molecules with each molecule of Sodium citrate dihydrate?

 

and when thay say "17.3 g copper sulfate pentahydrate in 100 mL of water"

is the 100ml of water beyond the 5 water molecules for each molecule of Copper sulfate?

 

(17.3g of Coper Sulfate) + (6 molecules of water for each molecule of coper sulfate) + (an additional 100ml of water)

 

 

When they say "sodium citrate dihydrate" 173g, they mean plain and simply, 173g of the dihydrate salt. The 2 H2O's are already figured into the weight. Comercially available sod citrate di is the norm. I have not yet encountered anything different.

Edited November 23, 2011 by pippo