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TrojanPoem
 one year ago
Question : Help please !
0.4122 grams of an organic compound was burnt totally , so the weight of the containers of absorbing water vapor and carbon dioxide were increased by 0.3618 grams , 0.762 grams respectively.
1 Find the percentage of carbon and hydrogen in the compound.
2 Is there any other element in the organic compound ? , Giving a reason.
TrojanPoem
 one year ago
Question : Help please ! 0.4122 grams of an organic compound was burnt totally , so the weight of the containers of absorbing water vapor and carbon dioxide were increased by 0.3618 grams , 0.762 grams respectively. 1 Find the percentage of carbon and hydrogen in the compound. 2 Is there any other element in the organic compound ? , Giving a reason.

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Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.0from your data, we can see that the ratio: water vapor and carbon dioxide =0.3618/ 0.762= 1/2 (approximated value)

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0What confuses me is that Organic compound (burnt)> nH2o + mCo2 so the sum of their masses must be equal or more to the compound itself but it is more.

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0I meant equal or less if equal > Only H , C if less H, C, other elements

phi
 one year ago
Best ResponseYou've already chosen the best response.1I assume the O comes from the air, and the organic compound does not contain O ?

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Maybe and maybe it was C2H5OH or something else with O

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0But I think you are right Phi, the O comes from the air as 0.3618 + 0.762 (not equal to) 0.4122

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0if so the mass of (O) = 0.3618 + 0.762  0.4122 = 0.7116 grams

phi
 one year ago
Best ResponseYou've already chosen the best response.10.4122 grams of an organic compound was burnt totally I would like to know the weight of any solid ash. but you have (CH other stuff) + O= H2O + CO2 (+ ash?) so the total weight of H2O + CO2  compound is the weight of added O ?

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0The problem already asks about ashes ( other elements) in the next part (2).

phi
 one year ago
Best ResponseYou've already chosen the best response.1my original thought was 2/18 of the H2O represents the H in the compound and 12/44 of the CO2 is the amount of C

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0dw:1435431964444:dw

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0so oxygen in Co2 = 0.762  0.21 = 0.552

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Hmm phi am I mistaken ?

phi
 one year ago
Best ResponseYou've already chosen the best response.1sounds right. But the question is Find the percentage of carbon and hydrogen in the compound.

phi
 one year ago
Best ResponseYou've already chosen the best response.1How do they measure percentage? By weight? or fractions of atoms?

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Mass of Carbon ( H only) / Mass of compound (C,H)

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Like normal percentages in maths

phi
 one year ago
Best ResponseYou've already chosen the best response.1so %C is 0.21 grams / 0.4122

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Yea , = 50.94 % ( 0.21/0.4122 times 100)

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0dw:1435432795512:dw

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0wait it's 0.292 so the compound contains other elements

phi
 one year ago
Best ResponseYou've already chosen the best response.1H + C add up to about 70% of the weight of the compound 30% must be something else.

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0So maybe it's oxygen. The reason is : There is other elements because the sum of mass of (H) + mass of (C) is less than the mass of the compound so there is other elements and their mass is Compound  mass (h+c) =

phi
 one year ago
Best ResponseYou've already chosen the best response.1could be. plus other stuff. I think you need more info.

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0I mean is the reasoning enough ( in your opinion ) ?

phi
 one year ago
Best ResponseYou've already chosen the best response.1we know how many grams of H and C were in the original and are now in the CO2 and H2O. If the compound "burned completely", that must be all its C and H (burned completely means every C or H combined with O from the air) We know the C and H account for 70% of the mass of the compound. that leaves 30% of the compound being other elements, including O or whatever.

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Thanks for the help @phi.
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