Recrystallizing Benzoic Acid Lab Report

Purpose/Introduction
The process of recrystallization is an important method of purifying a solid organic substance using a hot solution as a solvent. This method will allow the separation of impurities. We will analyze Benzoic Acid as it is dissolved and recrystallized in water and in a solvent of Methanol and water.
Reaction/Summary
In Experiment One we will be recrystallizing Benzoic Acid from water. In Experiment Two we will be recrystallizing Benzoic Acid using a solvent pair made up of Methanol and Water. The Seven step process of recrystallization consists of adding a solid organic substance into a solvent, then dissolving the chosen solute, decolorizing the solution, filtering solids, then recrystallize the solute by slowly cooling

It is faster due to the filter funnels surface area.

Results/Observations

Experimental data resulted as expected because it was found that on experiment one, Benzoic Acid could recrystallize with a better recovery percentage than the solvent pair in experiment two. The mass recovered in experiment one was 0.048g while experiment two had a mass recovery of 0.045g. Solvent(s) Used Mass of “Crude” (g) Mass of Recovered (g) Amount of Solvent Used (mL) Percent Recovered (%)
Experiment One Water (H2O) .051 .048 1.0 94.1
Experiment Two Methanol (MeOH)
And
Water (H2O) .049 .045 Methanol – 1.5

Water – 0.5 92

Conclusion
Both experiments were of fair solubility, but in the case of recrystallization of Benzoic Acid, Water was the best solvent to recrystallize acid the most. Experimental data determined that there was a difference of .003g between using the single solvent in comparison to the paired solvent. Data suggests that Water is the best solvent that will allow for better saturation and the best recrystallization of benzoic acid, this is largely due to water being a polar molecule whose properties allow for carboxylic acid groups, such as the one found in benzoic acid, to disassociate and donate protons to the water

You are given a known solid substance with its melting point which has high solubility in hot water and low solubility in cold water. You are assigned the following task:
i. Determine if the substance is pure ii. If impure, find a suitable method for its purification by using the given information about the substance
How would you proceed, clearly explain your rationale?
i. To find if it is a pure substance we see if there is a change in melting point. ii. If impure, preform recrystallization procedure to remove the impurities. Then calculate Percent Recovered on crystals formed, and preform melting point procedure.

2. You find that a solid substance you are trying to purify is very soluble in ethanol, but not very soluble in water. You decide that you are going to try to recrystallize it from a solvent pair, consisting of ethanol and water. is this decision based on sound rationale? Comment briefly.
1. The use ethanol and water in a solvent pair is perfect do due to ethanol having a high solubility while the water has low