gchem Q!!!!

[RING12]

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a sample of a compund of xennon and flurine contains molecules of a single type:XeFn, where n is a whole number. if 9.03 x10^20 of these XeFn molecules have a mass of 0.311g, what is the value of n?

the answer is 4. can some one explain it to me how can I get this answer.

 

[casper22]

a sample of a compund of xennon and flurine contains molecules of a single type:XeFn, where n is a whole number. if 9.03 x10^20 of these XeFn molecules have a mass of 0.311g, what is the value of n?

the answer is 4. can some one explain it to me how can I get this answer.

From Avagadro's No. we know, 1 mole = 6.02 x 10 ^23 molecules.

so 9.02 x 10^20 molecules = 9.02 x 10^20/6.02 x 10^23 = 1.5 x 10^-3

Now, MW = gm / moles = 0.311 gm / 1.5 x10^-3 = 207.33

MW = Xe+nF = 131.3 + n(19)

So the entire equation becomes,

131.3 +19👎 = 207.33
19n = 76
n = 76/19 = 4