Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Aetheria on July 09, 2009, 06:35:08 AM
-
Hi! I'm kind of confused on how to answer this question, the book didn't give an answer to this question so I am unsure. Please help, Thanks! :)
A compound of P & F was analyzed as follows: Heating 0.2324g of the compound in a 378-cm3 container turned all of it into gas, which had a pressure of 97.3mmhg at 77deg C. Then the gas was mixed with calcium chloride solution, which turned all of the F into 0.2631g of CaF2. Determine the molecular formula of the compound.
-
0.2324g of the substance contains the same amount of F as 0.2631g of CaF2 - that is enough to find out the empirical formula.
Use the other information to find out molar mass of the substance. It is different from the molar mass of empirical formula - what does it mean?
-
Hi! I'm kind of confused on how to answer this question, the book didn't give an answer to this question so I am unsure. Please help, Thanks! :)
A compound of P & F was analyzed as follows: Heating 0.2324g of the compound in a 378-cm3 container turned all of it into gas, which had a pressure of 97.3Hg at 77deg C. Then the gas was mixed with calcium chloride solution, which turned all of the F into 0.2631g of CaF2. Determine the molecular formula of the compound.
First,use Van der Waals gas equation---PV=nRT to calculate the Molar quantity of the compound and we've got the mass of compound,so the molecular weight can be calculated .Then, subtract the molecular mass of F from the compound then we can find out what element P is. Last, According to the mass of F calculated from 0.2631g of CaF2, the mass of P can be found and we've known the molecular weight of it so it's molar quantity can also be found out.Comparing the Molar quantity of P and F, the ratio of P and F in the formula can be determined .