Hi,
I am working on stoichiometry and limiting reactant problems. I have worked through examples in my book and I did them right and can solve for the excess, however there is one problem in the book that has confused me. I don't understand why they identified the limiting reactant as the one they did.
Equation
S8+4Cl2------4S2Cl2
200g of sulfur reacts with 100g of chlorine, what mass of disulfur dichloride is produced?
100g Cl2 *1mol cl2/70.91gcl2=1.410 mol Cl2
200g S2*1mol S8/256.5gS8=0.7797 mol S8
Isn't Sulfur the limiting reactant??? My book says its chlorine but I don't see how that is possible since sulfur is smaller and the ratio shows that.
Since 1 mole of S8 reacts with 4 moles of Cl2,
.779 moles S8 will need 3.116 moles of Cl2, but you only have 1.410 moles
Clearly the Cl2 is lacking here.
To determine the limiting reactant in a stoichiometry problem, you need to compare the number of moles of each reactant with the stoichiometric ratio from the balanced equation.
Let's calculate the number of moles of each reactant:
100g Cl2 * 1 mol Cl2 / 70.91g Cl2 = 1.410 mol Cl2
200g S8 * 1 mol S8 / 256.5g S8 = 0.7797 mol S8
Now let's look at the balanced equation:
S8 + 4Cl2 -> 4S2Cl2
According to the balanced equation, the stoichiometric ratio is 1 mole of S8 reacts with 4 moles of Cl2 to produce 4 moles of S2Cl2.
In this case, you have 0.7797 moles of S8 and 1.410 moles of Cl2.
Now, we can compare the two reactants based on the stoichiometric ratio.
For S8:
0.7797 moles * (4 moles Cl2 / 1 mole S8) = 3.1188 moles Cl2
For Cl2:
1.410 moles
As you can see, the ratio is flipped when comparing moles of S8 with the stoichiometric ratio. This means that for every 1 mole of S8, you need 4 moles of Cl2 to react completely.
Since you have 1.410 moles of Cl2, which is more than the 3.1188 moles required to react with the available 0.7797 moles of S8, the Cl2 is in excess.
Therefore, S8 is the limiting reactant in this case.
To find the mass of disulfur dichloride produced, we can use the stoichiometry:
0.7797 moles S8 * (4 moles S2Cl2 / 1 mole S8) * (135.04g S2Cl2 / 1 mol S2Cl2) = 420.35g S2Cl2
Therefore, the mass of disulfur dichloride produced is 420.35g.
To determine the limiting reactant in a stoichiometry problem, you need to compare the number of moles of each reactant and consider the balanced chemical equation.
To find the number of moles of chlorine (Cl2), you correctly converted the given mass (100g) to moles using the molar mass of chlorine (70.91 g/mol), which gives you 1.410 mol Cl2.
To find the number of moles of sulfur (S8), you correctly converted the given mass (200g) to moles using the molar mass of sulfur (256.5 g/mol), which gives you 0.7797 mol S8.
Next, you need to consider the stoichiometry of the balanced chemical equation. The coefficients in the balanced equation represent the mole ratio between reactants and products. In this case, the coefficient in front of Cl2 is 4, and the coefficient in front of S8 is 1.
Comparing the number of moles calculated for each reactant, you can see that there are more moles of chlorine (1.410 mol) than sulfur (0.7797 mol). However, you need to consider the ratio in the balanced equation.
According to the balanced equation, for every 4 moles of Cl2, you need 1 mole of S8. Since the sulfur to chlorine ratio is 1:4, you can determine that for every 1 mole of sulfur, you need 4 moles of chlorine.
Since you have fewer moles of sulfur (0.7797 mol) compared to chlorine (1.410 mol), sulfur is the limiting reactant. This means that chlorine is present in excess and will not be completely consumed in the reaction.
Therefore, based on the given information and the stoichiometry, sulfur is indeed the limiting reactant in this problem, not chlorine. It is possible that there is a mistake in your book, or there might be additional information or assumptions mentioned that you might have missed.