# Diprotic Acid Lab Report

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Diprotic Acid Lab Report
Purpose: The aim of this experiment was to determine if an unknown supplied food acid is citric acid (triprotic) or tartaric acid (diprotic acid)

Materials

4 x 100mL conical flasks 50mL burette rubber bulb 1 x 200mL beaker white tile retort stand 20mL volumetric pipette volumetric flask stopper 300mL distilled water marker 40mL 0.3M food acid burette clamp 0.1M sodium hydroxide magnetic flea magnetic stirrer glass funnel 1 x 200mL volumetric flask phenolphthalein 4 x 50mL beakers

Method
Part A: Making the food acid Place distilled water into a 25mL beaker Rinse the 20mL pipette with distilled water then with the 0.3M food acid Once the pipette has been cleaned, pipette 20mL of the food acid and place it
The average titre (19.3mL) was used for the volume of sodium hydroxide, whilst the concentration was 0.1 molL-1. 0.00193 moles of sodium hydroxide were used in this experiment.

C1 x V1 = C2 x V2
0.3 x 0.02 =0.03 x V2
V2 = (0.3 × 0.2)/0.03

V2 = 0.2 L

The equation, C1 x V1 = C2 x V2 was used in the experiment to find the volume of food acid. This equation was used because the food acid was being diluted. The volume of food acid was found to be 0.2L.

Food acid n = c x v n = 0.02 x 0.03 n = 0.0006 moles

Once the volume of food acid was found, the number of moles of food acid could be found using n = c x v. The number of moles of food was used was 0.0006 moles.

Ratio: NaOH : Food acid 0.00193 : 0.0006 3.2 : 1 3 : 1

The mole ratio needed to be used to compare the food acid and sodium hydroxide. We worked out that there was a three to one ratio as shown above. Due to being a three to one ratio, this means that the unknown supplied food acid is critic acid as it is a triprotic
This would give inaccurate results due to misreading the burette. If you estimate the readings on the burette, your results will not be precise and the titres many not be similar. Not viewing the meniscus at eye level would affect the titres because cause the titre values to vary due to guessing what the reading is on the meniscus. Poor lighting could occur which would make it difficult to look for subtle colour change, making the experimenter adding too much sodium hydroxide into the food acid solution because they didn’t see the first permanent colour change. Expelling the sodium hydroxide from the burette into the conical flask of food acid too fast, which would affect the titre, due to adding too much or not enough sodium hydroxide into the food acid. Misjudging the end point, which would affect the titre because more or less solution may have entered then the previous time, causing the titres results to vary. Adding too much or too little indicator, can affect your results due to the end point of the experiment occurring faster or slower than the previous

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