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Topic: General Chemistry problem  (Read 3480 times)

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Offline XenoCham

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General Chemistry problem
« on: October 25, 2006, 07:17:49 PM »
I am sorry.  I am not doing so well in General Chemistry, as I thought I was going to do.  I took Physiological Chemistry and loved it, so I registered for Gen Chem, and it's hard. :-\

But, here's a question that I hope you guys can't help me out with.  I would greatly appreciate it.
 
I did most of the work, but the last part stumpped me.  I do not know what they are asking for.
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4KCl  +  4 HNO3 +  O2 ------>   4 KNO3  +  2 Cl2  +  2 H2O

Calculate the mass of KCl requiered to produce 567g of potassium nitrate. 
What mass of chlorine is generated as well?
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I got :

567g KNO3     x      1 mol KNO3 / 101.11g KNO3    =    5.62 mol KNO3

5.62 mol KNO3   x    74.55 KCl / 1 mol KNO3    =   418g KCl

I got the mass for KCl, but I don't know what to do from there to get the mass for Cl.

I'm sorry, I hope that you guys that help me out on this one.  I really appreciate it again.
take care ^_^
« Last Edit: October 25, 2006, 07:41:04 PM by XenoCham »

Offline Dan

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Re: General Chemistry problem
« Reply #1 on: October 25, 2006, 07:33:08 PM »
4KCl  +  4 HNO3  ------>   4 KNO3  +  2 Cl2  +  2 H2O

Can you check this equation? It isn't balanced, and looks really odd to me.
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Offline XenoCham

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Re: General Chemistry problem
« Reply #2 on: October 25, 2006, 07:38:38 PM »
I'm sorry, you are right. 
This is the right way


4 KCl  +  4  HNO3   +   O2  ------->  4 KNO3  +  2 Cl2  + 2 H2O

thank you for noticing that.

Offline Dan

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Re: General Chemistry problem
« Reply #3 on: October 25, 2006, 07:53:07 PM »
OK, yeah that makes sense now

1) How many moles of KCl do you have? We will call this number "n"
2) so how many moles of Cl- do you have?
3) How many Cl2 molecules are formed by one ion of Cl-? hint: it's not a whole number
4) So how many moles of Cl2 molecules are formed by one mole of Cl-?
5) So how many moles of Cl2 molecules are formed by "n" moles of Cl-? We will call this number of moles "m"
6) what is the mass of "m" moles of Cl2?
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