Solve Molecular Formula of Silicon-Fluorine Compound

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Discussion Overview

The discussion revolves around determining the molecular formula of a silicon-fluorine compound based on its mass percentage composition and gas laws. It involves calculations related to empirical and molecular weights, as well as the application of the ideal gas law.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant suggests using the ideal gas law (PV=nRT) to find the number of moles of the compound, indicating uncertainty about the next steps after calculating n.
  • Another participant proposes finding the molecular weight of the compound and then determining the empirical formula, leading to a general formula representation of the compound as (Si_xF_y)_n.
  • A later reply presents a detailed calculation for the molecular weight and empirical formula, concluding with a proposed molecular formula of Si2F6, but seeks confirmation on its correctness.
  • One participant confirms the correctness of the proposed molecular formula.

Areas of Agreement / Disagreement

There is a general agreement on the calculations leading to the molecular formula, as one participant confirms the final result. However, the initial steps and methods used to arrive at the conclusion contain some uncertainty and are not fully resolved.

Contextual Notes

The discussion includes assumptions about the ideal gas behavior and the accuracy of the empirical formula calculations. There may be dependencies on the definitions of molecular and empirical weights that are not fully clarified.

Who May Find This Useful

Students and enthusiasts in chemistry, particularly those interested in molecular formula determination and gas law applications.

babbagee
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Analysis of a newly discovered gaseous silicon-fluorine compound shows that it contains 33.01 mass % silicon. At 27oC 2.60g of the compound exerts a pressure of 1.50 atm in a 0.250-L vessel. What is the molecular formula of the compound?
I guess PV=nRT needs to be used. P,V,R, and T are given, i guess the only thing to sove for is n. That gives me the total moles of silicon fluorine. But i don't know where to go after that.

Thanks
 
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First of all find molecular wt of comp

now find empirical formula

n= mol. wt / empirical formula

and hence the formula for compound as [tex](Si_xF_y)_n[/tex]
 
Does this look right??

m=RT/PV = ((2.60)(.0821)(300))/((1.50)(.250)) = 170.7
Mol wt=170.7

33.01 %Si -100 = 66.99%F

33.01g Si and 66.99gF

33.01gSi(1mol/28.09gSi)=1.17mol
66.99gF(1mol/19.00gF)=3.52mol
Si1.17F3.52
emp formula = SiF3
Mol wt/emp wt = 170.7/85 = 2
mol formula = Si2F6

Is this correct.
 
Yes it is
 

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