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Topic: Homework help - how to do this problem??  (Read 4703 times)

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Offline wuzbob

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Homework help - how to do this problem??
« on: September 28, 2009, 11:00:38 AM »
Okay so basically before our big exam, we are required to do five practice problems. Well, I got through the first 4 but this is the only one left, any suggestions?

5.   Lead (II) ions can be precipitated from solution with potassium chloride to form lead sulfide and potassium ions.  Write the molecular, total, and net ionic equations for this reaction.  When 28.5 grams of potassium chloride is added to a solution containing 25.7 g of lead (II) ions the mass of lead (II) chloride that forms is 29.4 g.  Determine the theoretical yield of lead (II) chloride and calculate the percent yield for this reaction.

Offline Yggdrasil

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Re: Homework help - how to do this problem??
« Reply #1 on: September 28, 2009, 12:23:30 PM »
5.   Lead (II) ions can be precipitated from solution with potassium chloride to form lead sulfide and potassium ions.

This is probably a typo.  The products should be lead (II) chloride and potassium ions.

So, I would start by writing out the chemical formula for all of the chemical species involved (lead (II) ions, potassium chloride, lead (II) chloride, and potassium ions), then using these to write a balanced chemical reaction.

Offline wuzbob

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Re: Homework help - how to do this problem??
« Reply #2 on: September 28, 2009, 10:53:33 PM »
5.   Lead (II) ions can be precipitated from solution with potassium chloride to form lead (II) chloride and potassium ions. Write the molecular, total, and net ionic equations for this reaction.  When 28.5 grams of potassium chloride is added to a solution containing 25.7 g of lead (II) ions the mass of lead (II) chloride that forms is 29.4 g.  Determine the theoretical yield of lead (II) chloride and calculate the percent yield for this reaction.


-----that's the real problem sorry about the typo.

Offline Borek

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Re: Homework help - how to do this problem??
« Reply #3 on: September 29, 2009, 02:54:33 AM »
Now follow Ygg's advice.
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Offline Yggdrasil

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Re: Homework help - how to do this problem??
« Reply #4 on: September 29, 2009, 12:51:26 PM »
That is not a chemical reaction.  A chemical reaction has a left hand side with the reactants and a right hand side with the products.  For example, the reaction between silver nitrate and magnesium chloride to form solid silver chloride and magnesium nitrate can be written:

2AgNO3 (aq) + MgCl2 (aq) --> 2AgCl2 (s) + Mg(NO3)2 (aq)

You need to write a comparable equation for your reaction.

Offline sjb

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Re: Homework help - how to do this problem??
« Reply #5 on: September 29, 2009, 01:14:53 PM »
That is not a chemical reaction.  A chemical reaction has a left hand side with the reactants and a right hand side with the products.  For example, the reaction between silver nitrate and magnesium chloride to form solid silver chloride and magnesium nitrate can be written:

2AgNO3 (aq) + MgCl2 (aq) --> 2AgCl2 (s) + Mg(NO3)2 (aq)

You need to write a comparable equation for your reaction.

That ought to be AgCl, shouldn't it?

Offline Borek

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Re: Homework help - how to do this problem??
« Reply #6 on: September 29, 2009, 02:58:47 PM »
Obvious typo.
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