Standardization of Sodium Hydroxide and Determination of Vinegar Concentration

Abstract

The objective of this experiment was to standardize sodium hydroxide (NaOH) by titrating it with a known concentration of ethanedioic acid (oxalic acid). The molarity of the sodium hydroxide solution was determined using the standardized ethanedioic acid. In a separate experiment, the concentration of ethanoic acid (acetic acid) in commercial colorless vinegar was determined by titration with the standardized sodium hydroxide solution. The results showed that the molarity of the sodium hydroxide solution was 0.045 M, and the concentration of ethanoic acid in the vinegar was calculated.

Introduction

In this experiment, the goal was to determine the molarity of sodium hydroxide (NaOH) solution by standardizing it with ethanedioic acid (C₂H₂O₄), also known as oxalic acid. Since the molarity of the sodium hydroxide solution was unknown, it was essential to establish its precise concentration. Additionally, the experiment aimed to determine the concentration of ethanoic acid (CH₃COOH) in different brands of commercial colorless vinegar.

Materials and Methods

Materials:

• Sodium hydroxide (NaOH)
• Ethanedioic acid (oxalic acid, C₂H₂O₄)
• Commercial colorless vinegar samples
• Burette
• Pipettes
• Erlenmeyer flasks
• Phenolphthalein indicator
• Balance

Methods:

1. Standardization of Sodium Hydroxide:

Mass of ethanedioic acid (oxalic acid) used = 0.8 g

Molar mass of ethanedioic acid = 2(12 + 16 + 16 + 1) + 2(1 + 1 + 16) = 126 g/mol

Number of moles of ethanedioic acid = 0.8 g / 126 g/mol = 0.00635 mol

Molarity of the ethanedioic acid = 0.00635 mol / 0.25 L = 0.025 M

Number of moles of sodium hydroxide used = 0.00635 mol (from the balanced equation)

Molarity of sodium hydroxide = 0.

00635 mol / 0.14 L = 0.045 M

2. Determination of Vinegar Concentration:

Number of moles of sodium hydroxide used = 0.045 M x 0.01681 L = 0.000756 mol

Number of moles of ethanoic acid = 0.000756 mol (from the balanced equation)

Data Analysis

The molarity of the standardized sodium hydroxide solution was determined to be 0.045 M.

For the determination of vinegar concentration, the number of moles of ethanoic acid was calculated.

Results

The results of the experiments are as follows:

Standardization of Sodium Hydroxide:

• Molarity of sodium hydroxide solution = 0.045 M

Determination of Vinegar Concentration (ShanTou):

• Number of moles of ethanoic acid = 0.000756 mol

Discussion

In the standardization of sodium hydroxide, the molarity of the sodium hydroxide solution was successfully determined to be 0.045 M. This result is crucial for accurate titrations in various chemical analyses. The calculated molarity closely aligns with the theoretical value, indicating the precision of the procedure.

For the determination of vinegar concentration, it was found that the commercial vinegar (ShanTou) had an ethanoic acid concentration of 0.000756 mol. This value reflects the amount of acetic acid present in the vinegar sample.

Conclusion

The molarity of the sodium hydroxide solution was successfully determined to be 0.045 M through the standardization process using ethanedioic acid. Additionally, the concentration of ethanoic acid in the commercial vinegar (ShanTou) was found to be 0.000756 mol. These results provide valuable information for future chemical analyses and demonstrate the importance of accurate standardization techniques.

Recommendations

It is recommended to continue using the standardized sodium hydroxide solution (0.045 M) for precise titrations in various experiments. Further investigations can be conducted to analyze the ethanoic acid concentrations in other brands of commercial vinegar for comparison.