Qualification > Sciences
chem question
Bani:
--- Quote from: nid404 on October 02, 2009, 04:06:50 pm ---Z is PbCO3.....so when it is heated it decomposes to form lead oxide and carbon dioxide
yeah u can add reactions...
--- End quote ---
but they r asking for the molecular formula of Z (PbCO3 is the empirical formula...so what will the molecular formula be?) howcome its CO2 (what happened to the Pb?)
nid404:
they r asking for the molecular formula of Z!! I'm sorry i thought they were asking for the molecular formula of the gas evolved....haste..sorry
okay so
11.2g of PbO would be 11.2/223=0.05 moles....if Z was 0.05 moles....it means their ratio is same...so molecular mass should be PbCO3..
what does the mark scheme say?
Bani:
--- Quote from: nid404 on October 02, 2009, 05:04:14 pm ---they r asking for the molecular formula of Z!! I'm sorry i thought they were asking for the molecular formula of the gas evolved....haste..sorry
okay so
11.2g of PbO would be 11.2/223=0.05 moles....if Z was 0.05 moles....it means their ratio is same...so molecular mass should be PbCO3..
what does the mark scheme say?
--- End quote ---
hehe no problem
no, i don't have the markscheme. but the method u've shown is what i worked it out as...dunno if its correct...its 3 marks though
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