What is the theoretical yield of PI3 from the reaction of 27.0 g of P and 68.0 g I2? 2P(s)+3I2(s) 2PI3(s)
73.5 g
Well, let's calculate it out!
First, we need to determine which reactant is the limiting reagent. To do this, we compare the moles of P and I2 and see which one is present in the smallest amount.
The molar mass of P is approximately 31.0 g/mol, and the molar mass of I2 is approximately 253.8 g/mol.
Here's a clown-like calculation for the moles of each reactant:
27.0 g P * (1 mol P / 31.0 g P) ≈ 0.87 mol P
68.0 g I2 * (1 mol I2 / 253.8 g I2) ≈ 0.27 mol I2
Since we have fewer moles of I2 than P, I2 is the limiting reagent.
Now, using the stoichiometry of the balanced equation, we can determine the theoretical yield of PI3. According to the equation, 2 moles of P reacts with 3 moles of I2 to produce 2 moles of PI3.
So, 0.27 mol I2 * (2 mol PI3 / 3 mol I2) ≈ 0.18 mol PI3
Finally, we can convert the moles of PI3 to grams using its molar mass. The molar mass of PI3 is approximately 411.8 g/mol.
0.18 mol PI3 * (411.8 g PI3 / 1 mol PI3) ≈ 74.3 g PI3
Therefore, the theoretical yield of PI3 is approximately 74.3 grams. Just keep in mind that this is the maximum amount you can obtain under ideal conditions. In reality, there may be losses due to side reactions or other factors.
To calculate the theoretical yield of PI3, you need to determine which reactant limits the amount of product that can be formed. This is known as the limiting reagent.
Step 1: Convert the masses of P and I2 to the number of moles.
- The molar mass of P is 30.97 g/mol.
- The molar mass of I2 is 253.8 g/mol.
- Use the formula: moles = mass (g) / molar mass (g/mol).
Moles of P = 27.0 g / 30.97 g/mol = 0.872 mol
Moles of I2 = 68.0 g / 253.8 g/mol = 0.268 mol
Step 2: Determine the stoichiometric ratio of the reactants and products.
According to the balanced equation, 2 moles of P react with 3 moles of I2 to produce 2 moles of PI3.
Step 3: Identify the limiting reagent.
Compare the mole ratio of P to I2:
Moles of P / Stoichiometric coefficient of P = 0.872 mol / 2 = 0.436 mol
Moles of I2 / Stoichiometric coefficient of I2 = 0.268 mol / 3 = 0.089 mol
The smaller resulting number, 0.089 mol, represents the limiting reagent. It means that I2 is the limiting reagent in this reaction.
Step 4: Calculate the theoretical yield.
To determine the theoretical yield of PI3, use the amount of limiting reagent (I2) and the mole ratio from the balanced equation.
Moles of PI3 = Moles of I2 (limiting reagent) x (2 moles PI3 / 3 moles I2)
Moles of PI3 = 0.089 mol x (2/3) = 0.0593 mol
Step 5: Convert moles of PI3 to grams.
- The molar mass of PI3 is 411.8 g/mol.
- Use the formula: mass (g) = moles × molar mass (g/mol).
Mass of PI3 = 0.0593 mol × 411.8 g/mol = 24.4 g
Therefore, the theoretical yield of PI3 from the reaction is 24.4 grams.
You have a limiting reagent problem How do I know? Because BOTH reactants are given. So basically you work two simple stoichiometry problems and use the one which produces the smaller amount of product as the limiting reagent. Here is the procedure for the first one.
Write and balance the equation.
Here is a worked example of a simple stoichiometry problem.
http://www.jiskha.com/science/chemistry/stoichiometry.html
Post your work if you get stuck.