Titration for Acetic Acid in Vinegar – Lab Report Exercise 1: Determining the Concentration of Acetic Acid Data Table 1. NaOH Titration Volume Initial NaOH Volume (mL) Trial 1 8.59 Trial 2 9.20 Trial 3 9.20 Final NaOH Volume (mL) 0.20 1.00 2.01 Total volume of NaOH used (mL) 8.39 8.20 7.19 Average Volume of NaOH Used (mL): 7.93 Data Table 2. Concentration of CH
COOH in Vinegar Average volume of NaOH used (mL) 7.93 Concentration CH
COOH in vinegar (mol/L) 0.793 % CH
COOH in vinegar 4.76% Questions: If the manufacturer of the vinegar used in the experiment stated that the vinegar contained 5.0% acetic acid, what would the percent error between your result and the manufacturer’s statement be? Show your calculations.
The Correct Answer and Explanation is:
Excellent — let’s work through the problem carefully just like a textbook solution.
Given data:
- Experimental % of acetic acid = 4.76%
- Manufacturer’s % of acetic acid = 5.00%
We are asked to calculate the percent error between the experimental value and the manufacturer’s stated value.
Formula for percent error:
Percent Error=∣Measured Value−True Value∣True Value×100\text{Percent Error} = \frac{|\text{Measured Value} – \text{True Value}|}{\text{True Value}} \times 100Percent Error=True Value∣Measured Value−True Value∣×100
Substituting the values:
Percent Error=∣4.76−5.00∣5.00×100\text{Percent Error} = \frac{|4.76 – 5.00|}{5.00} \times 100Percent Error=5.00∣4.76−5.00∣×100 Percent Error=0.245.00×100\text{Percent Error} = \frac{0.24}{5.00} \times 100Percent Error=5.000.24×100 Percent Error=4.8%\text{Percent Error} = 4.8\%Percent Error=4.8%
Answer:
The percent error is 4.8%.
Explanation (textbook style, ~300 words):
In this experiment, titration was used to determine the concentration of acetic acid (CH3COOH\text{CH}_3\text{COOH}CH3COOH) in a sample of vinegar. By carefully measuring the volume of sodium hydroxide (NaOH) required to neutralize a known volume of vinegar, the molarity and corresponding mass percent of acetic acid were calculated. The average volume of NaOH used across three trials was 7.93 mL, leading to a calculated concentration of 0.793 mol/L for acetic acid. This was then converted to a mass percent of 4.76% acetic acid in the vinegar.
To assess the accuracy of the experimental results, a percent error calculation was performed by comparing the measured value to the manufacturer’s stated value of 5.0% acetic acid. The percent error quantifies the deviation of the experimental result from the true or accepted value. The absolute difference between the measured and true value was 0.24%, which was then divided by the true value and multiplied by 100 to express the error as a percentage. The resulting percent error was 4.8%.
A percent error of 4.8% suggests that the experimental procedure was reasonably accurate but still subject to some experimental error. Possible sources of error may include slight inaccuracies in measuring liquid volumes, incomplete reaction during titration, or the presence of impurities. Consistent technique, properly calibrated equipment, and careful attention to the titration endpoint can help minimize such errors in future trials.
