Qualification > Sciences
CHEM AND BIO HELP AND TIPS HERE
WARRIOR:
--- Quote from: Dana on June 06, 2010, 04:35:11 pm ---you guys when they tell us to describe a way to make a salt like lead nitrate, how do we know which one to put in excess, the lead oxide or the nitric acid??
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lead oxide afcourse , because we want aall the nitric acid to be used up , thne we filter to remove the excess lead oxide and we evaporate the filtrate for obtaining crystals
Raywin:
--- Quote from: mdwael on June 06, 2010, 04:31:47 pm ---That makes sense, thank u
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No Probs, Glad to help.. :)
MasterMath:
Its always the insoluble substance which is the lead oxide in your case .. so you can filter it off .. its just a way of making sure all nitric acid reacted :D
Dana:
--- Quote from: Kimo Jesus on June 06, 2010, 04:37:11 pm ---lead oxide afcourse , because we want aall the nitric acid to be used up , thne we filter to remove the excess lead oxide and we evaporate the filtrate for obtaining crystals
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why don't we want all the acid to be used up? ::) plus sometimes they say add excess acid dont they?
the_grim_reaper:
--- Quote from: Lariemeeva on June 06, 2010, 04:03:49 pm ---https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Q 7-a (i)
In the MS it's written "an equation that gives: alkene + alkane or alkene + alkene + hydrogen"
Why is that. Cracking of alkanes --> alkene + hydrogen not alkene + alkane
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--- Quote from: Lariemeeva on June 06, 2010, 04:03:49 pm ---https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414
Q 7-a (i)
In the MS it's written "an equation that gives: alkene + alkane or alkene + alkene + hydrogen"
Why is that. Cracking of alkanes --> alkene + hydrogen not alkene + alkane
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I can't really understand your question. Really ambiguous language. Well answering what I can grasp.
Lady lets put it like this. Here its decane and you have to give butene. Now after that, you've got six carbons and 14 hydrogens. So you can make anything in the world that you like from them. You can simply make it hexane or if you like hydrogen, you can make it hydrogen and hexene. That's why there are only two combinations, that you've already stated because you have to produce butene.
If butene wasn't stated, then you can make ethene, propane and pentene.
Basically, what I'm trying to state is that you must make an alkene from cracking. After that, you can make anything from the remaining stuff. Say if you want to crack ethane, then you can make ethene and hydrogen. Only 2 products are formed. You don't get an alkane here.
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