Thermochemistry: Heat and Volume Effects in Solution

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the experiment conducted, six two-component mixtures were made. The compounds used in the experiment were methanol, ethanol, acetone, and dichloroethane. The mentioned compounds were organic compounds. Before doing the experiment, the results were predicted. The prediction was based on the intermolecular force present in a compound. Moreover, the structure of the compound also plays a role in the prediction.

There are three types of intermolecular forces found in organic compounds, namely London dispersion, otherwise known as Van der Waals, dipole-dipole, hydrogen bond. The strongest among the three was the hydrogen bond, while van der Waals is the weakest. Every compound has the London dispersion force.

The predictions in the experiment were all exothermic reactions and the volume was less than 8. This was due to the fact that every compound have different structure and intermolecular force present. Methanol and ethanol both have an IMF of hydrogen bond, dichloroethane and acetone has a dipole-dipole moment. Ethanol has bigger structure than methanol; acetone is also bigger compared to dicloroetahne.

Upon mixing the compounds it was predicted that an exothermic reaction will occur since the compounds does not have the same IMF present. The volume prediction was due to the structure of the compound. Smaller compounds tend to hide under bigger compounds. The observed result in the experiment was the same with the prediction, except for the volume of methanol-acetone two-component. The result difference was due to the human error committed by the conductor.

Conclusion

The intermolecular forces (IMF) present in the covalently bonded compounds are London dispersion, dipole-dipole moment, and hydrogen bonding. Hydrogen bonding is the strongest IMF, then dipole-dipole moment, and lastly the London dispersion as the weakest. These forces hold the compounds together. In order to separate the compounds with each other, energy is required. Upon separation, energy is released causing the reaction to be exothermic. Moreover, the structure if the compound plays a role in the volume of the solution. When compounds having different structures and IMF were mixed, the smaller molecule tends to hide under the bigger molecule, making the final volume of the mixture less compared to water. Hence, the increase in volume of the solution results to the increase of temperature.

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