Question

Preface: Aluminum foil was reacted will hydrochloric acid and copper 2 chloride. The copper solid from the reaction was placed on filter paper and dried.

Data obtained from the lab is below

Data Table

Mass of Aluminum: 0.29g

Mass of filter paper: 0.35g

Mass of reacted filter paper: 0.49g

Final mass of Copper: 0.11g

10mL of CuCl2: 0.100 CuCl2 molarity

Volume of Copper Solution: ?

Moles of Copper: 0.001g (0.1 molarity x 0.01 liters)

1. Write an equation to represent the reaction that occurred.

2 Al (s) + 3 CuCl2 (aq) à 2 AlCl3 (aq) + 3 Cu (s)

2. What is the new solid that was produced?

Copper

3. Calculate the theoretical yield of the solid (you will have to calculate a limiting reagent first)

4. What is your percent yield?

5. Logically explain why did not achieve 100% yield

Answer 1

Answer 2

The equation that represents the reaction that occurred is:

2 Al (s) + 3 CuCl2 (aq) → 2 AlCl3 (aq) + 3 Cu (s)

The new solid that was produced is copper (Cu).

To calculate the theoretical yield, we need to determine the limiting reagent. We can do this by comparing the moles of aluminum (Al) and copper(II) chloride (CuCl2) in the reaction.

From the given data: Mass of aluminum = 0.29 g Molar mass of aluminum (Al) = 26.98 g/mol

Moles of aluminum = mass/molar mass = 0.29 g / 26.98 g/mol = 0.0107 mol

Moles of copper(II) chloride (CuCl2) = 0.1 Molarity x 0.01 liters = 0.001 mol

Since the stoichiometric ratio between Al and CuCl2 is 2:3, we can see that the moles of CuCl2 (0.001 mol) are limiting the reaction. Therefore, CuCl2 is the limiting reagent.

To find the theoretical yield of copper (Cu), we use the stoichiometric ratio between CuCl2 and Cu, which is 3:3 or 1:1. Since 0.001 mol of CuCl2 produces 0.001 mol of Cu, the theoretical yield of Cu is also 0.001 mol.

To convert the theoretical yield from moles to grams, we use the molar mass of copper (Cu), which is 63.55 g/mol:

Theoretical yield of Cu = 0.001 mol x 63.55 g/mol = 0.06355 g or 63.55 mg

The percent yield is calculated by dividing the actual yield (mass of copper obtained) by the theoretical yield and multiplying by 100:

Percent yield = (Actual yield / Theoretical yield) x 100

Actual yield of Cu = Final mass of copper - Initial mass of filter paper = 0.11 g - 0.35 g (mass of filter paper) = -0.24 g (assuming there was an error in the data)

Since the actual yield is negative, it indicates that there was an error in the measurements or calculations. A negative yield is not physically possible and suggests a problem in the experiment or data collection process.

To achieve 100% yield, several factors can contribute to the deviation from the theoretical yield:

1. Losses during the transfer and filtration process: Some of the copper solid may have been lost during filtration or transferred to the filter paper, resulting in a lower actual yield.

2. Incomplete reaction: The reaction may not have gone to completion, meaning not all of the copper(II) chloride reacted with aluminum to form copper.

3. Side reactions: There may have been unintended side reactions that consumed some of the reactants or produced additional products.

4. Experimental errors: Errors in measurement, calculation, or equipment calibration can lead to deviations from the expected results.

It is crucial to carefully control experimental conditions, accurately measure reactants, and minimize losses during the reaction and purification steps to achieve a higher percent yield