Understanding the Reaction:
The reaction you're describing is the synthesis of tin(II) iodide (SnI₂):
Sn + I₂ → SnI₂
What We Know:
* Starting mass of tin (Sn): 15.0 g
* Excess iodine (I₂): This means we have enough iodine to ensure all the tin reacts.
* Actual yield of tin iodide (SnI₂): 66.3 g
What We Need to Find:
* Percent yield: This is the ratio of the actual yield to the theoretical yield, expressed as a percentage.
Steps to Solve:
1. Calculate the theoretical yield:
* Convert the mass of tin to moles: 15.0 g Sn / 118.71 g/mol Sn = 0.126 mol Sn
* From the balanced equation, 1 mol Sn produces 1 mol SnI₂. Therefore, 0.126 mol Sn will produce 0.126 mol SnI₂.
* Convert moles of SnI₂ to grams: 0.126 mol SnI₂ × 325.5 g/mol SnI₂ = 41.0 g SnI₂ (theoretical yield)
2. Calculate the percent yield:
* Percent yield = (actual yield / theoretical yield) × 100%
* Percent yield = (66.3 g / 41.0 g) × 100% = 161.7%
The Answer:
The percent yield of the reaction is 161.7%.
Important Note: A percent yield greater than 100% is unusual and suggests a potential error in the experiment. It could be due to factors such as:
* Impurities in the product: The actual yield might include impurities, leading to a higher measured mass.
* Incorrect measurements: Errors in weighing the reactants or products can affect the yield calculation.
* Side reactions: Other reactions may occur, leading to additional products that are weighed as part of the desired product.
It's important to consider these possibilities when interpreting a percent yield greater than 100%.
