Single Replacement Reaction Stoichiometry Data Table

Balanced Chemical Equation: Al(s) + CUSO4(aq) →

Describe the appearance of the copper(II) sulfate solution and the aluminum foil before the reaction starts.
Describe your observations of the solution during the reaction.
Describe the appearance of the solution and any solids after the reaction.
Describe the appearance of the solid after it is dried.
Was all of the copper(II) sulfate reacted in this lab? Explain your answer both with observations and calculations.
Identify the excess and limiting reactants.
Identify TWO aqueous substances that were washed away from the final solid.
If the solids were not washed before drying, how would this change the copper metal yield?
If the copper is not completely dried, how would this change the yield of copper metal?
Explain why the percent yield was not 100%. What are some sources of error

The Correct Answer and Explanation is :

Here’s the breakdown of your experiment based on the given reaction:

1. Appearance of Copper(II) Sulfate Solution and Aluminum Foil Before the Reaction

Copper(II) Sulfate Solution (CuSO₄): The copper(II) sulfate solution is blue due to the presence of Cu²⁺ ions dissolved in water.
Aluminum Foil (Al): The aluminum foil is shiny and metallic in appearance before the reaction.

2. Observations of the Solution During the Reaction

The blue color of the copper(II) sulfate solution begins to fade as the reaction progresses. This is due to the reduction of Cu²⁺ ions to copper metal (Cu), which precipitates out of the solution.
Small bubbles or effervescence may be observed, indicating the release of hydrogen gas as aluminum reacts with the sulfate ions.
Aluminum foil may become rougher or corroded as it undergoes oxidation.

3. Appearance of the Solution and Any Solids After the Reaction

After the reaction, the solution will turn pale or colorless due to the depletion of copper(II) ions. Copper metal (Cu) will be deposited as a reddish-brown solid at the bottom of the reaction vessel.
There may also be a small amount of remaining aluminum sulfate (Al₂(SO₄)₃) in solution.

4. Appearance of the Solid After It Is Dried

After drying, the copper metal solid will appear as reddish-brown crystals or powder, depending on the method of collection.

5. Was All of the Copper(II) Sulfate Reacted in This Lab?

Observations: If the reaction stopped early or a color change wasn’t observed throughout the entire solution, some of the copper(II) sulfate may not have been completely reacted.
Calculations: The stoichiometric calculations can help confirm whether all of the copper(II) sulfate was reacted. Compare the moles of copper(II) sulfate used with the moles of aluminum used. If the molar ratio isn’t met, then excess copper(II) sulfate remains in the solution.

6. Excess and Limiting Reactants

The limiting reactant is aluminum (Al), because it is typically the one that runs out first, given its stoichiometry in the balanced equation.
The excess reactant is copper(II) sulfate (CuSO₄), because there will likely be leftover copper(II) sulfate once the aluminum is completely consumed.

7. Two Aqueous Substances Washed Away from the Final Solid

Water (H₂O): Water is used to wash away any soluble byproducts.
Aluminum Sulfate (Al₂(SO₄)₃): Any remaining aluminum sulfate in the solution is washed off the copper metal.

8. Effect of Not Washing the Solids Before Drying

If the solids were not washed, the copper metal would contain impurities such as aluminum sulfate or other soluble byproducts, which would decrease the purity of the copper and affect the yield.

9. Effect of Not Completely Drying the Copper

If the copper is not fully dried, any residual water would add to the mass of the final product, making it seem like a higher yield. The actual yield of copper metal would be less than calculated.

10. Why the Percent Yield Was Not 100%

The percent yield is often less than 100% due to several factors:

Incomplete Reaction: Not all of the copper(II) sulfate may have reacted due to a limited amount of aluminum or insufficient reaction time.
Loss of Copper During Filtration: Some copper metal could be lost during washing or filtration, leading to a lower final mass.
Purity Issues: The copper metal may contain impurities such as aluminum sulfate, reducing its effective mass.
Experimental Errors: Losses during handling, incomplete drying, or inaccurate measurements could affect the final yield.

In summary, the percent yield is rarely 100% due to experimental inefficiencies, incomplete reactions, or losses during various stages of the process. Each of these factors can contribute to discrepancies between theoretical and actual yields in a lab setting.