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Specialty Chemistry Forums => Citizen Chemist => Topic started by: Lonn on July 17, 2010, 10:46:16 AM

Title: moles of the reactants with H2O
Post by: Lonn on July 17, 2010, 10:46:16 AM
Pb(NO3)2(aq) + 2 NaCl(aq) → PbCl2(s) + 2 NaNO3(aq)

suppose I was mixing this in a lab to get the desired products, with who of Pb(NO3)2(aq) or 2 NaCl(aq) would H2O be with and how many moles of H2O would it be.

I am gonna give an example so you better understand my question because I don't know how to word it exactly

In  BaCl2(aq) + Na2SO4(aq) ------------> BaSO4(s) + 2 NaCl(aq)

if I where mixing this, BaCl2 would be [1 mole of BaCl2*2H2O] while Na2SO4 would be [1 mol of Na2SO4] at least stoichiometry wise)

so my question is: are any of the moles of the reactants in Pb(NO3)2(aq) + 2 NaCl(aq) → PbCl2(s) + 2 NaNO3(aq) with *H2O like BaCl2 is?

also if you could tell me the why behind this so in the future I can figure it out by myself as I can't find any explanation in my books I would be grateful, but if you can answer only, please go ahead. If you can give me any useful comment at all please do. If you can explain how to know this so I'll do it myself please do as I understand those are the principles of this forum.
Title: Re: moles of the reactants with H2O
Post by: ContinuousProcess on August 26, 2010, 01:44:36 AM
From my understanding it just means the BaCl2 crystals are coordinated with water molecules. (Dry looking powder also can be a hydrated compound.)

My guess is that the answer to your question depends on the source of your reagent.

******Ehhhh  old thread is old. sorry *******************
Title: Re: moles of the reactants with H2O
Post by: discodermolide on August 26, 2010, 07:56:14 AM
I understand this to mean that you have aqueous solutions of the various reagents, which are then mixed to give the products, one of which precipitates out of the solution. Therefore the amount of water is unimportant.
Title: Re: moles of the reactants with H2O
Post by: vmelkon on September 01, 2010, 12:30:26 PM
The water of hydration is important if it is part of your reactant, for example lead nitrate. It would have an effect on the quantity in grams that you will need.
Title: Re: moles of the reactants with H2O
Post by: discodermolide on September 01, 2010, 03:05:30 PM
The water of hydration is important if it is part of your reactant, for example lead nitrate. It would have an effect on the quantity in grams that you will need.
Sure it will but with an aqueous solution this will be minimal
Title: Re: moles of the reactants with H2O
Post by: ContinuousProcess on September 03, 2010, 12:35:03 AM
Sure it will but with an aqueous solution this will be minimal

Well it would still affect your yield...
Title: Re: moles of the reactants with H2O
Post by: discodermolide on September 03, 2010, 01:47:15 AM
Sure it will but with an aqueous solution this will be minimal

Well it would still affect your yield...
Yes it will, but minimal, H20 has a MWt of 18, compare that with lead nitrate, the effect will be minimal
Title: Re: moles of the reactants with H2O
Post by: Borek on September 03, 2010, 03:34:37 AM
I understand this to mean that you have aqueous solutions of the various reagents, which are then mixed to give the products, one of which precipitates out of the solution. Therefore the amount of water is unimportant.

What if you are asked to prepare 1 mole of solid barium sulfate, starting from barium chloride and sulfuric acid? How much barium chloride would you weight?
Title: Re: moles of the reactants with H2O
Post by: discodermolide on September 03, 2010, 06:15:13 AM
I understand this to mean that you have aqueous solutions of the various reagents, which are then mixed to give the products, one of which precipitates out of the solution. Therefore the amount of water is unimportant.

What if you are asked to prepare 1 mole of solid barium sulfate, starting from barium chloride and sulfuric acid? How much barium chloride would you weight?

Depends if you use the anhydrous form or the di-hydrate, 208.23 g/mol (anhydrous)
244.26 g/mol (dihydrate)