DAT GC Problem

[DesiDenty]

Advertisement - Members don't see this ad

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.

 

[lex1489]

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

 

[nainaaz]

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

 

[Troyvdg]

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