Qualification > Sciences
CHEM AND BIO HELP AND TIPS HERE
MasterMath:
--- Quote from: Dana on June 06, 2010, 04:40:00 pm ---why don't we want all the acid to be used up? ::) plus sometimes they say add excess acid dont they?
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Well if you add excess acid for example , how can you remove the excess :P ? its liquid you cant really remove it :P
And remember here we are making salts .. so we want to just have the right amount of solution to evaporate then cool and filter.. so we can use excess oxide and remove it , then we have solution of equal moles of Lead ions and Nitrate ions.. but if you use excess acid you cant remove it so they wont be balanced.
And yeah sometimes they do use excess acid , thats when you want to react like a metal fully but not for getting salts :D
Dana:
--- Quote from: MasterMath on June 06, 2010, 04:39:19 pm ---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
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ahaa, well thanks alot :)
Dana:
--- Quote from: MasterMath on June 06, 2010, 04:40:59 pm ---Well if you add excess acid for example , how can you remove the excess :P ? its liquid you cant really remove it :P
And remember here we are making salts .. so we want to just have the right amount of solution to evaporate then cool and filter.. so we can use excess oxide and remove it , then we have solution of equal moles of Lead ions and Nitrate ions.. but if you use excess acid you cant remove it so they wont be balanced.
And yeah sometimes they do use excess acid , thats when you want to react like a metal fully but not for getting salts :D
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mhmm i see. thanks!
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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and thank you!
J.Darren:
--- Quote from: blackberry on June 06, 2010, 01:54:26 pm ---Got a doubt from the 2005 m/j paper 3 chemistry paper.
When 0.015 moles of iodine react with 0.045 moles of chlorine to form 0.030 moles of a single product. So, we have to complete the equation. The answer is:
I2 + 3Cl2 = 2ICl3 my question is how come theres 3 atms of Cl formed?
Oh and second question....when iodine reacts with zinc nd wen u decrease the concentration of iodine how come less of zinc is used up?
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compare the mole ratio.
0.015 : 0.045
1 : 3
i : cl
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