dubois928 Posted December 2, 2007 Share Posted December 2, 2007 What would be the proportion/ratio of zinc metal to hydrochloric acid to make a zinc chloride solution, which in in turn would be evaporated to precipitate zinc chloride crystals? Thanks, Ken Link to comment Share on other sites More sharing options...
YT2095 Posted December 2, 2007 Share Posted December 2, 2007 Zn + 2 HCl → ZnCl2 + H2 that should help Link to comment Share on other sites More sharing options...
dubois928 Posted December 2, 2007 Author Share Posted December 2, 2007 So that would be 1 part Zinc to 2 parts Hydrochloric acid? Sorry if I have it way wrong, I'm kind of new at this. Thanks, Ken Link to comment Share on other sites More sharing options...
insane_alien Posted December 2, 2007 Share Posted December 2, 2007 yeah 1mol of zinc will react with 2 mols of hydrochloric acid. Link to comment Share on other sites More sharing options...
YT2095 Posted December 2, 2007 Share Posted December 2, 2007 a mole is 6.02x10^23 atoms of ANY element or molecule, for Zinc 1 mol is 65.4 grams, and H=1 and Cl= 35.5 so when you add them you get 36.5 grams for 1 mole of HCl, but you`ll need 2 moles so ya double it to 73 grams. although you`ll not be able to buy pure HCl as it`s a Gas, so you`ll have to factor in the percentage of it in the acid you`re using. Link to comment Share on other sites More sharing options...
dubois928 Posted December 2, 2007 Author Share Posted December 2, 2007 Wow thats a lot of zinc. I am having trouble understanding the measurement of moles. Just to make sure I'm have this right, would I take 2ml of 30% HCl and dissolve 1 gram of zinc in it? Or does the amount change because it's 30% and not 100%? Thanks, Ken Oh, never mind YT explained it. So what would I have to do to get the amount required for 30% HCl? Link to comment Share on other sites More sharing options...
YT2095 Posted December 2, 2007 Share Posted December 2, 2007 it is a lot if you`re planning on making it in whole Molar amounts, but these work right down into nano grams and lower too, it`s just a maths thing. and I`m really crap at maths as anyone (incl myself) will tell you. but your Ratio is 65.4 : 73 that`s all I dare say. I`ll ask Insane Alien to do that bit Link to comment Share on other sites More sharing options...
insane_alien Posted December 2, 2007 Share Posted December 2, 2007 okay, you have 15(ish)mmol of zinc so you'll need 30(ish)mmol of HCl 30mmol of HCl is 1.1g so you'll need 3.7g of the 30% solution (assuming it is weight for weight) to disolve it. this would equate to about 3.7ml call it 4ml to make sure you disolve it all. Link to comment Share on other sites More sharing options...
dubois928 Posted December 2, 2007 Author Share Posted December 2, 2007 So, if I'm doing my math correctly, if I had a 40% solution of HCl instead of 30%, I would need 2.75ml of of it? Thanks, Ken Link to comment Share on other sites More sharing options...
YT2095 Posted December 2, 2007 Share Posted December 2, 2007 yup, that comes up about right when I fiddle with my calculator a bit Link to comment Share on other sites More sharing options...
insane_alien Posted December 2, 2007 Share Posted December 2, 2007 i concur. i get 2.75ml as well. Link to comment Share on other sites More sharing options...
dubois928 Posted December 2, 2007 Author Share Posted December 2, 2007 One more thing: okay, you have 15(ish)mmol of zinc so you'll need 30(ish)mmol of HCl How did you get 15mol Zinc and 30mol HCl? Thanks, Ken Link to comment Share on other sites More sharing options...
insane_alien Posted December 2, 2007 Share Posted December 2, 2007 15 mmol. mmol is millimol a thousandth of a normal mol. i don't like working with 0.000XXX numbers so i use the prefixes. it's still SI though i more commonly work with kmols(thosand mols) Link to comment Share on other sites More sharing options...
dubois928 Posted December 2, 2007 Author Share Posted December 2, 2007 So 1.0g Zn = 15mmol? Ken Link to comment Share on other sites More sharing options...
insane_alien Posted December 2, 2007 Share Posted December 2, 2007 pretty much. its 1/65.4 to be more exact. Link to comment Share on other sites More sharing options...
dubois928 Posted December 2, 2007 Author Share Posted December 2, 2007 Finally, here is all of my math, hopefully correct: ZnCl2 1 mol Zn -to- 2 mol HCl 1 mol Zn = 65.4g 1 mol H = 1.0g 1 mol Cl = 35.5g 1 mol HCl = 36.5g 2 mol HCl = 73.0g 15mmol Zn -to- 30mmol HCl 15mmol Zn = 1.0g 30mmol HCl = 1.1g 30% HCl = 0.3 1.1/0.3 = 3.666 (3.7) 3.7g = 3.7ml ZnCl2 = 1.0g Zn -to- 3.7ml 30% HCl Thanks, Ken Link to comment Share on other sites More sharing options...
insane_alien Posted December 2, 2007 Share Posted December 2, 2007 yeah we got there a while ago. Link to comment Share on other sites More sharing options...
dubois928 Posted December 2, 2007 Author Share Posted December 2, 2007 Great! Thank you Insane_Alien and YT for all of your help! I think I have a better understanding of the math behind chemistry now. Ken Link to comment Share on other sites More sharing options...
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