Question

Design an Experiment Design an experiment that can be used to determine the percent yield of anhydrous copper(II) sulfate when copper(II) sulfate pentahydrate is heated to remove water.

Short answer

To design an experiment for determining the percent yield of anhydrous copper(II) sulfate when copper(II) sulfate pentahydrate is heated, gather the necessary materials, including CuSO4·5H2O sample, balance scale, heating apparatus, crucible, crucible tongs, and safety gear. Begin by measuring the starting mass of the copper(II) sulfate pentahydrate. Next, calculate the theoretical mass of anhydrous copper(II) sulfate based on the formula \( \frac{{\text{{mass of hydrate}} \times \text{{molar mass of anhydrous}}}}{{\text{{molar mass of hydrated}}}} \). Heat the sample in the covered crucible until it turns white. After cooling, measure the mass of the anhydrous copper(II) sulfate, and calculate the percent yield using the formula \( \frac{{\text{{Experimental Mass}}}}{{\text{{Theoretical Mass}}}} \times 100\% \). For example, if the mass of hydrate was 5g, the theoretical mass of anhydrous copper(II) sulfate would be 3.194g. Using these in the yield calculation gives the percent yield of the experiment.

Step-by-step solution

Gather Materials

To perform this experiment, you will need the following materials: - Copper(II) sulfate pentahydrate (CuSO4·5H2O) sample - Balance scale (accurate to at least 0.01g) - Heating apparatus (Hot plate or Bunsen burner) - Crucible with lid - Crucible tongs - Lab gloves, goggles, and apron

Measure the Starting Mass of Copper(II) Sulfate Pentahydrate

Before heating the sample, measure its mass on the balance scale. Record the mass of the crucible and the mass of the crucible with the sample. Subtract the mass of the crucible from the mass of the crucible with the sample to find the mass of the Copper(II) sulfate pentahydrate.

Calculate Theoretical Mass of Anhydrous Copper(II) Sulfate

To determine the theoretical mass of anhydrous copper(II) sulfate that can be produced, use the ratio of the molar mass of anhydrous copper(II) sulfate (CuSO4) to copper(II) sulfate pentahydrate (CuSO4·5H2O). The molar mass of CuSO4 is approximately 159.61 g/mol and that of CuSO4·5H2O is approximately 249.68 g/mol. The formula for calculating the theoretical mass of anhydrous copper(II) sulfate produced is (mass of hydrate x molar mass of anhydrous)/ molar mass of hydrated) Example: If the mass of hydrate is 5g, the theoretical mass of anhydrous copper(II) sulfate would be: (5g * 159.61g/mol) / 249.68g/mol = 3.194g

Heat the Sample

Place the Copper(II) sulfate pentahydrate sample in the crucible and cover it with the lid. Heat the sample using the heating apparatus. Be sure to follow safety protocols and use appropriate personal protective equipment. Continue heating the sample until it appears to be completely white and no more water of hydration is released. Allow the crucible to cool before handling.

Measure the Final Mass of Anhydrous Copper(II) Sulfate

After the crucible has cooled, measure the mass of the crucible with the anhydrous copper(II) sulfate. Subtract the mass of the crucible to obtain the mass of the anhydrous copper(II) sulfate.

Calculate the Percent Yield

The percent yield of the reaction can be calculated using the following formula: Percent Yield = (Experimental Mass / Theoretical Mass) x 100% Plug in the values obtained in Steps 3 and 5 to calculate the percent yield of anhydrous copper(II) sulfate from the given sample of copper(II) sulfate pentahydrate.

Key concepts

Copper(II) sulfate pentahydrate

Copper(II) sulfate pentahydrate, with its chemical formula CuSO₄·5H₂O, is a bright blue crystalline solid that is commonly used in laboratories for various experiments. The 'pentahydrate' part of its name indicates that each unit of copper sulfate contains five water molecules. This water is known as water of hydration and is integral to the structure of the compound.
This compound is often used in experiments involving heating because the process can remove these water molecules, changing the compound's properties. When you heat copper(II) sulfate pentahydrate, it loses its water content and transforms into an anhydrous form, which is white and powdery in appearance.
Being aware of these changes is crucial in calculating theoretical and percent yields, as it involves precise measurement before and after the heating process.

Anhydrous copper(II) sulfate

Anhydrous copper(II) sulfate, denoted as CuSO₄, is the form of copper sulfate that has no water molecules bound to it. This form is achieved by heating copper(II) sulfate pentahydrate to remove the water of hydration.
In laboratory experiments, the transition from the pentahydrate to the anhydrous form is visually evident as a color change from blue to white. This change signifies that the water molecules have been successfully removed.
Anhydrous copper(II) sulfate is used in various applications such as a desiccant due to its property of easily absorbing water. In the context of percent yield experiments, obtaining an accurate mass of anhydrous copper(II) sulfate is essential to measuring how effective the process was.

Theoretical yield

Theoretical yield refers to the maximum amount of product that can be generated from a chemical reaction, based purely on stoichiometric calculations from the balanced chemical equation. It assumes perfect conversion and no loss, which is nearly impossible in a real-world scenario.
In the context of heating copper(II) sulfate pentahydrate to convert it into anhydrous copper(II) sulfate, the theoretical yield involves using the molar masses of both forms to predict how much of the anhydrous form should be produced. The calculation involves:

• The molar mass of CuSO₄·5H₂O: approximately 249.68 g/mol
• The molar mass of CuSO₄: approximately 159.61 g/mol

This prediction is crucial because it provides a benchmark to compare against the actual amount obtained, thus allowing you to calculate the percent yield.

Experimental procedures

Experimental procedures refer to the steps taken and methods used in conducting an experiment, ensuring both accuracy and safety. For the experiment involving heating copper(II) sulfate pentahydrate, the procedure includes several critical phases:

• Preparation: Gather your materials, including CuSO₄·5H₂O, a scale, a heating source such as a Bunsen burner, and safety equipment.
• Measurement: Accurately weigh the initial sample and apparatus to ensure the data's reliability.
• Heating: Safely heat the sample to remove water content while adhering to safety guidelines.
• Post-heating: Allow time for the sample to cool before measuring the mass of the resulting anhydrous CuSO₄. All these steps are essential in minimizing errors that could impact the percent yield calculation.

Chemical reactions

Chemical reactions are processes where substances change into new products, involving rearrangement of atoms. In this experiment, the chemical reaction being studied is the dehydration of copper(II) sulfate pentahydrate.
During heating, the chemical process involves breaking the bonds between the copper sulfate and the water molecules. This is an example of an endothermic reaction where energy is required to separate water molecules from the compound, leading to the formation of anhydrous copper(II) sulfate.
Understanding the chemical transformations occurring in the reaction not only aids in the calculation of theoretical yields but also advances comprehension of how to optimize experiments to achieve maximum percent yield.