DAT GC Problem

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DesiDenty

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I was just wondering how to solve this problem without a calculator. It was on the GC section of Topscore test #2.

A compound found to have the composition of 29.8% Xe, 44.3 Pt and 25.9% F by mass has the empirical formula of

Answer was XePtF6.
 
Estimate evvvverything.

Assume 100g substance so % = g of each element. Divide the gram mass of each element by its MW which gives
~.2 mol Xe
~.2 mol Pt
~1.2 mol F

Find the integer ratio (i.e. divide by the smallest mol number)
.2/.2 = 1
.2/.2 = 1
1.2/.2 = 6

XePtF6
 
I was just wondering how to solve this problem without a calculator. It was on the GC section of Topscore test #2.

A compound found to have the composition of 29.8% Xe, 44.3 Pt and 25.9% F by mass has the empirical formula of

Answer was XePtF6.


i would solve by rounding off..
first assume initially 100 g of compound
composition Xe= 29.8g/131g/mole (rounding 29.8/131=30/130=0.2..)
composition Pt= 44.3/195 (40/200=0.2..)
composition F= 25.9/18.9 (25/20=1.2..)
therefore the ratio's of composition Xe is 0.2/0.2= 1
Pt= 0.2/0.2=1
F= 1.2/0.2=6
hope it helps
 
i would solve by rounding off..
first assume initially 100 g of compound
composition Xe= 29.8g/131g/mole (rounding 29.8/131=30/130=0.2..)
composition Pt= 44.3/195 (40/200=0.2..)
composition F= 25.9/18.9 (25/20=1.2..)
therefore the ratio's of composition Xe is 0.2/0.2= 1
Pt= 0.2/0.2=1
F= 1.2/0.2=6
hope it helps

+1 to this method
 
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