Insightful Magnesium and Hydrochloric Acid Reaction

The reaction between magnesium and hydrochloric acid is a classic chemistry experiment used to demonstrate exothermic reactions. This experiment involves measuring the temperature change of the solution as a known mass of magnesium reacts with hydrochloric acid. The heat released during the reaction can be used to calculate the enthalpy change.

Magnesium and Hydrochloric Acid Experiment

This experiment involves adding hydrochloric acid to magnesium metal, which results in a highly exothermic reaction that generates heat and hydrogen gas. By measuring the temperature change of the solution during the reaction, it is possible to calculate the enthalpy change of the reaction.

This experiment is commonly performed by undergraduate students to gain a better understanding of chemical reactions and thermochemistry. Here, we will provide a detailed laboratory procedure for performing the Reaction Between Magnesium and Hydrochloric Acid experiment.

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Materials

Magnesium ribbon or powder, Hydrochloric acid (1.0 M), Test tube, Thermometer, Stopper with a small hole, Graduated cylinder, Balance, and Stopwatch

Safety Precautions

1. Wear safety goggles and gloves
2. Handle hydrochloric acid with care as it is corrosive
3. Keep the test tube away from the edge of the bench to avoid spills
4. Ensure that the test tube is stable on the bench

Procedure

1. Clean and dry the test tube before use.
2. Measure 10 mL of 1.0 M hydrochloric acid using a graduated cylinder and pour it into the test tube.
3. Weigh a small piece of magnesium ribbon or a small amount of magnesium powder and record the mass.
4. Add the magnesium to the test tube containing the hydrochloric acid.
5. Immediately insert the stopper with the thermometer into the test tube, ensuring that the thermometer is fully submerged in the solution and not touching the sides or bottom of the test tube.
6. Stir the solution gently with the thermometer to ensure even mixing.
7. Record the initial temperature of the solution.
8. Observe and record any changes that occur during the reaction, such as gas formation or bubbling.
9. Measure the final temperature of the solution when the reaction is complete.
10. Repeat the experiment two more times to ensure accurate results.

Calculations

Calculate the mass of magnesium used in the reaction.

Calculate the heat absorbed by the solution using the equation:

Q = m x c x ΔT

where Q is the heat absorbed, m is the mass of the solution (10 g assuming 10 mL of solution has a density of 1 g/mL), c is the specific heat capacity of water (4.18 J/g °C), and ΔT is the change in temperature of the solution.

Calculate the enthalpy change of the reaction using the equation:

ΔH = -Q/m

where ΔH is the enthalpy change, Q is the heat absorbed by the solution, and m is the mass of magnesium used.

Calculate the average enthalpy change from the three trials.

Report the average enthalpy change with uncertainty and state any sources of error or potential improvements to the experiment. Additionally, discuss the relationship between the amount of heat released and the amount of magnesium used, and how this can be used to determine the enthalpy change of the reaction.

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Plotting of Graph

1. Make a table of the mass of magnesium used and the amount of heat released in each trial.
2. Arrange the data in ascending order of the mass of magnesium used.
3. Plot a graph with heat released on the y-axis and the mass of magnesium used on the x-axis.
4. Draw a best-fit line through the data points.
5. Use the slope of the line to calculate the heat released per unit mass of magnesium.

The resulting graph can help identify any trends or patterns in the relationship between the amount of magnesium used and the amount of heat released. It can also be used to compare the heat released by different amounts of magnesium and make predictions about the amount of heat that would be released for different masses of magnesium.

The Reaction Between Magnesium and Hydrochloric Acid experiment is an effective way to introduce students to exothermic reactions and thermochemistry. By measuring the temperature change of the solution during the reaction, it is possible to calculate the enthalpy change of the reaction, providing a better understanding of the underlying chemistry.

This experiment is widely used in undergraduate chemistry courses and provides valuable insight into the properties of chemical reactions.

Overall, the Reaction Between Magnesium and Hydrochloric Acid experiment is a valuable tool for teaching the principles of thermochemistry and chemical reactions to students.