Calorimetry: Measuring Heat Transfer in Chemical Reactions

Introduction

Calorimetry is a technique used in physical and analytical chemistry to determine the concentration of colored compounds in solution by measuring the wavelength and intensity of electromagnetic radiation in the visible spectrum. It is crucial to ensure that no heat is lost to the environment during these measurements. Calorimetry is particularly valuable for detecting subtle color differences that the human eye cannot discern due to its incorporation of a photocell capable of detecting light passing through a solution. Additionally, calorimetry plays a vital role in controlled laboratory environments for measuring heat energy transferred during chemical or physical processes.

Risk Assessment

Risk	Potential Injury	Person in Danger	Solution
Copper Sulfate	Burn skin Eye irritation	Yourself	Mop up small spills using absorbent paper and wearing gloves Wear goggles and eye protection
Colorimeter	Electric shock Hot or burned skin	Yourself and others	Immediately disconnect the colorimeter Remove the storage compartment lid and try to gently drain most of the liquid. Then leave the unit to thoroughly dry
Cuvettes	Cutting yourself Scratches	Yourself and others around you	Handle the equipment safely
Beaker	Cutting yourself Scratches	Yourself and other students and staff around you	If it breaks, inform a teacher so it can be cleaned and removed. Get quality help now Bella Hamilton Verified writer Proficient in: Chemistry 5 (234) “ Very organized ,I enjoyed and Loved every bit of our professional interaction ” +84 relevant experts are online Hire writer Do not attempt this yourself

Vocational Scenario

You are a technical assistant at ChemCalQuip, tasked with determining the calorie content of a fizzy drink in a chemical factory using calorimetry.

Experimental Procedure

Equipment Used:

• Cuvettes
• Colorimeter
• Pipette
• Light Source
• Monochromator
• Sample Cell
• Detector
• Meter

Step 1: Calibrate the weighing balance to be used.

Step 2: Weigh between 2.50 and 2.70g of hydrated copper sulfate (CuSO₄·5H₂O).

Step 3: Carefully transfer the hydrated copper sulfate to a beaker, accurately recording measurements for mass transfer.

Step 4: Add 25cm³ of hot distilled water to the beaker, stir, and dissolve the hydrated copper sulfate completely.

Step 5: Accurately transfer the entire solution to a 100cm³ volumetric flask and make up the solution to 100cm³ with more distilled water.

Step 6: Calculate the precise concentration of the resulting copper sulfate solution, which is approximately 0.1M, and label the volumetric flask.

Step 7: Dilute some of the stock copper sulfate solution to create four other solutions with concentrations of approximately 0.08M, 0.06M, 0.04M, and 0.02M. Calculate the precise concentration of each solution created.

Step 8: Select an appropriate color filter and calibrate the colorimeter (or visible spectrometer) according to the manufacturer's instructions using the stock solution and distilled water.

Step 9: Measure and record the absorbance of each copper sulfate solution (approximately 0.1M, 0.08M, 0.04M, 0.02M) and distilled water (0.00M) using the calibrated colorimeter (or visible spectrometer).

Step 10: Plot a calibration curve of absorbance against the concentration of Copper sulfate.

Step 11: Measure and record the absorbance of sample A and sample B, the unknown concentrations of copper sulfate solution supplied by the teacher.

Step 12: Using the calibration curve, determine the concentration of Sample A and B.

Limitations

1. Stearic Acid: Skin contact may cause irritation, itching, stinging, burning, redness, rashes, inflammation, hives, blisters, sun sensitivity, and scaly skin. Rinse affected areas immediately.
2. Paraffin Wax: Inhalation of toxins may lead to vomiting, nausea, headaches, and potential pollution resulting in lung cancer. Wear a mask and goggles.
3. Liquid Thermometer: Fragile and limited to visible liquid columns, unsuitable for surface temperature measurements.
4. Digital Stop Clock: Requires electricity or batteries and does not wind.
5. Clamp and Stand: Fragile if not tightened or handled carefully.
6. Bunsen Burner: Limited flame size determined by gas port capacity.
7. Heat-Proof Mat: May cause severe thermal burns upon accidental contact.
8. Tripod and Gauze: May result in burns to hands when placed under a Bunsen burner.
9. Digital Thermometer: Easily damaged if dropped or when battery power is depleted.
10. 250cm³ Beaker: Fragile and prone to breakage.
11. Boiling Tube: Suitable for high-temperature applications only.

Method for the Experiment

1. Place 250cm³ of water into a beaker.
2. Set the beaker on a tripod and gauze and heat the water using a Bunsen burner until it boils.
3. Maintain a steady temperature by adjusting the Bunsen flame.
4. Fill 1/4 of a boiling tube with stearic acid.
5. Set up the equipment as shown in the diagram, ensuring the thermometer does not touch the side or bottom of the boiling tube. The bulb or probe of the thermometer should be submerged in the stearic acid.

Variables

Independent Variable: The mass of the stearic acid being heated.

Dependent Variable: The temperature change in the system.

Controlled Variable: The amount of paraffin and stearic acid used.

Statistical Analysis

Factors that Affect Stearic Acid and Paraffin Wax in the Experiment:

1. Melting Point: The melting point affects the measurement as it is necessary for the substances to melt for accurate temperature measurement using a liquid thermometer.
2. Boiling Point: Boiling point impacts the experiment because the substances must liquify, and if the water does not boil, accurate data cannot be obtained.
3. Size of the Molecule: Molecule size affects the time required for results, as larger compounds take longer to break down.

Data and Results

Filter Color and Absorbance Data

Temperature Data (Stearic Acid and Paraffin Wax)

Conclusion

In conclusion, calorimetry is a powerful technique for measuring heat energy transferred during chemical or physical processes. This experiment successfully utilized calorimetry to determine the concentration of copper sulfate solutions and involved various safety precautions to mitigate potential hazards. The limitations of certain materials and equipment were identified, and their impact on the experiment was considered. Overall, the experiment yielded valuable data and insights into the behavior of stearic acid and paraffin wax under controlled conditions.