A compound containing #"36.5%"# of sulfur and #"63.5%"# of iron reacts with a compound containing #"27.6%"# oxygen and #"724%"# of iron. What is the balanced equation and the theoretical yield of iron oxide?
The theoretical yield of the iron oxide will be 880 g.
The first thing you have to do is determine the formula for iron sulfide by using the known percent composition of sulfur in the compound. Let's assume that the formula for iron sulfide looks like this
The percent composition of sulfur in this formula would be
This means that you have
The ratio between iron ans dulfur in rion sulfide is
The chemical equation looks like this
Now do the same for the iron oxide.
This will get you
If you take
This means that your balanced chemical equation will look like this
Since oxygen is in excess, all the moles of iron sulfide will take part in the reaction. Use the compound's molar mass to determine how many moles you have in your 1.0-kg sample
This means that the reaction will produce
The theoretical yield of the reaction will thus be
Rounded to two sig figs, the number of sig figs you gave for the mass of iron sulfide, the answer will be
The balanced equation is
The theoretical yield of
A) BALANCED EQUATION
In order to write a balanced chemical equation for this reaction, we must determine the formulas for iron sulfide and iron oxide, as they have more than one formula because iron forms more than one ion.
Determine the formulas for iron sulfide and iron oxide.
Because 36.5% is 35/100, we can assume a 100-g sample of iron sulfide, and we can say that there are 36.5 g S and 63.5 g Fe. We can convert the masses to moles by dividing the mass of each element by its molar mass (atomic mass on the periodic table in grams.
Mole ratios for
Iron and sulfur are present in a 1:1 ratio.
The formula for iron sulfide is
Again, because 27.6% is 27.6/100, we assume a 100-g sample of iron oxide, and we can say that there are 27.6 g oxygen and 72.4 g Fe. Again, we can convert the masses to moles by dividing the mass of each element by its molar mass (atomic mass on the periodic table in grams.
Mole ratios for O and Fe
Divide the moles of each element by the smallest number of moles.
Mole ratios must be in whole numbers, so multiply both ratios times
The mole ratio for
The chemical formula for iron oxide is
Balanced Chemical Equation
B) THEORETICAL YIELD OF IRON OXIDE
We need the molar masses of
Molar mass of
Molar mass of
Mole ratio of iron oxide and iron sulfide is:
Calculate Theoretical Yield of Iron Oxide
Convert 1 kg FeS to 1000 g FeS. Then convert the mass of FeS to moles using its molar mass. Multiply moles FeS times the mole ratio between iron oxide and iron sulfide to get moles iron oxide. Multiply moles of iron oxide times its molar mass.
(answer rounded to two significant figures because of 1.0 kg)