Transcript 677-#5 answered

PROBLEM 4 OF LIMITING REAGENT SET.
2S (s) + 3O2 (g)  2SO3 (g)
FIRST DETERMINE IF THERE IS A LIMITING REAGENT.
/
FIND MOLES OF ALUMINUM METAL
MOLES = MASS/GFM S
MOLES = 1.0 g s/ 32.04g/mol
MOLES = 0.031191 mol S
FIND MOLES OF OXYGEN GAS.
MOLES = MASS/GFM O2
S
O2
MOLES = 1.0 g O2 / 32.00g/mol
MOLES = 0.03125mol O2
= 2 = 0.031191 ,
3
0.03125
.666 <
1
The actual ratio is larger than the
theoretical, therefore the actual ratio
fraction is too large, the denominator is
to small,
O2 limiting.
2S (s) + 3O2 (g)  2SO3 (g)
STEP 1 Identify known (the substance that can be converted to moles), choose the correct
equation to convert to moles.
MOLES = MASS/GFM O2
MOLES = 1.0 g O2 / 32.00g/mol
MOLES = 0.03125mol O2
STEP 2 RATIO known to objective,
O2
SO3
= 3 = 0.03125 ,
2
X
X = 0.020833 mol SO3
STEP 3 Convert Objective to required units.
MOLES = MASS/GFM SO3
0.020833 mol= mass/ 80.06g/mol
Mass = 1.314 g SO3
% yield = experimental/theoretical
0.80 / 1.667 =47.9% = 48%