Determination of Titratable Acidity (Lactic Acid) of a Milk Sample (IS 1479:1960)

MicroChem's Experiments

11 Oct 202006:21

Summary

TLDRThis video tutorial guides viewers through an experiment to determine the titratable acidity of a milk sample. The process involves chemical preparation, density determination, sample preparation, titration, and calculation. Key steps include preparing a 0.1 normal sodium hydroxide solution, determining milk density, and conducting a titration with phenolphthalein as an indicator. The video demonstrates how to calculate the acidity of the milk sample, which is found to be 0.131% as lactic acid. This step-by-step guide is ideal for those interested in learning the process of milk acidity analysis.

Takeaways

🧪 The video is an experiment to determine the milk acidity or titratable acidity of a milk sample.
📋 The process involves several steps: chemical preparation, milk density determination, sample preparation, titration, and calculation.
🔧 Required equipment and chemicals include a balance machine, burette with stand, conical flask, pipette with filler, 0.1 normal sodium hydroxide solution, and phenolphthalein indicator solution.
🧴 For the 0.1 normal sodium hydroxide solution, dissolve 4 grams of sodium hydroxide pellets in 900 ml distilled water and make up to 1000 ml, then standardize the solution.
🌿 Phenolphthalein indicator is prepared by dissolving 2 grams of fenugreek powder in 100 ml ethanol.
🔬 Milk density should be determined separately, with instructions provided in another video linked in the description.
🥛 Prepare the sample by taking 10 ml of milk in a conical flask and adding 10 ml of distilled water, then mix well.
💧 Add a few drops of phenolphthalein indicator to the milk sample.
📏 Conduct titration using 0.1 normal sodium hydroxide solution and note the initial and final burette readings when the solution turns light pink.
📊 Calculate the acidity using the formula provided, where the sample's acidity was determined to be 0.131% as lactic acid.

Q & A

What is the purpose of the experiment described in the video?
-The purpose of the experiment is to determine the titratable acidity of a milk sample.
What are the key steps involved in the milk acidity test?
-The key steps include chemical preparation, milk density determination, sample preparation, titration, and calculation.
What chemicals and equipment are required for this experiment?
-The experiment requires a balance machine, burette with stand, conical flask, pipette with filler, 0.1 normal sodium hydroxide solution, and phenolphthalein indicator solution.
How is the 0.1 normal sodium hydroxide solution prepared?
-To prepare the 0.1 normal sodium hydroxide solution, dissolve 4 grams of sodium hydroxide pellets in 900 ml of distilled water and make up the final volume to 1000 ml. The solution should be standardized before use.
How is the phenolphthalein indicator prepared?
-The phenolphthalein indicator is prepared by dissolving two grams of phenolphthalein powder in 100 ml of ethanol.
What is the first step after preparing the chemicals for the experiment?
-The first step after preparing the chemicals is to determine the milk density by following the procedure in a separate video mentioned in the description.
How is the milk sample prepared for titration?
-To prepare the milk sample, take 10 ml of the milk sample in a conical flask, add 10 ml of distilled water, and shake it to mix properly.
How is the titration performed in the experiment?
-Titration is performed by adding a few drops of phenolphthalein indicator solution to the milk sample, followed by adding 0.1 normal sodium hydroxide solution from a burette with vigorous agitation until the solution turns light pink.
How do you calculate the acidity of the milk sample?
-The acidity is calculated by using the sample volume, the volume of sodium hydroxide used (final burette reading minus initial reading), and the density of the milk sample. These values are plugged into the equation provided in the video to determine the acidity as a percentage of lactic acid.
What is the final result obtained in the experiment?
-The final result shows that the acidity of the milk sample is 0.131% as lactic acid.

Outlines

00:00

🧪 Introduction to Milk Acidity Experiment

This section introduces the video, where viewers are welcomed to a demonstration on determining the acidity of a milk sample. The steps involved in the experiment are outlined, including chemical preparation, milk density determination, sample preparation, titration, and calculation. The necessary equipment and chemicals, such as a balance machine, burette, conical flask, sodium hydroxide solution, and phenolphthalein indicator, are listed. The video sets the stage for a detailed walkthrough of the analysis process.

05:25

🔬 Step-by-Step Milk Acidity Determination

This paragraph details the experiment's procedure, beginning with the preparation of 0.1 normal sodium hydroxide solution by dissolving 4 grams of sodium hydroxide pellets in distilled water, followed by standardization. It also explains the preparation of phenolphthalein indicator by dissolving fenugreek powder in ethanol. The process continues with determining milk density and preparing the milk sample by mixing it with distilled water. The titration process is described, including the addition of phenolphthalein indicator, the use of sodium hydroxide in the burette, and stopping the titration when the solution turns light pink. The paragraph concludes by setting up the calculation for determining the milk's acidity.

📊 Calculation of Milk Acidity

This section explains the final step of the experiment, where the acidity of the milk sample is calculated. The given values, including the sample volume, the amount of sodium hydroxide used, and the density of the milk, are input into the equation provided. By solving the equation, the acidity is determined to be 0.131% as lactic acid, concluding the experiment.

Mindmap

Keywords

💡Milk Acidity

Milk acidity, also known as titratable acidity, measures the presence of acid in milk, typically expressed as a percentage of lactic acid. In the video, determining the milk acidity is the primary focus of the experiment, where it is calculated through a titration process. This measurement helps in assessing the freshness and quality of the milk sample.

💡Titration

Titration is a laboratory technique used to determine the concentration of a substance in a solution by adding a reagent of known concentration until a reaction is completed. In this video, titration is used to find the acidity of the milk sample, where sodium hydroxide is gradually added until the milk solution turns light pink, indicating the end point of the reaction.

💡Sodium Hydroxide

Sodium hydroxide (NaOH) is a strong base used in the titration process to neutralize the acid in the milk sample. The video discusses the preparation of a 0.1 normal solution of sodium hydroxide, which is then used in the experiment to determine the milk's acidity. The correct preparation and use of this solution are crucial for accurate results.

💡Phenolphthalein

Phenolphthalein is a pH indicator used in titrations, which turns pink in basic solutions. In the video, a phenolphthalein solution is added to the milk sample before titration, and the change in color to light pink signals the end point of the titration, indicating that the acidity in the milk has been neutralized by the sodium hydroxide.

💡Milk Density

Milk density refers to the mass per unit volume of milk, typically measured in grams per milliliter (g/mL). The video mentions determining the milk density as part of the experiment, which is necessary for accurately calculating the acidity. The density helps in understanding the milk's composition and quality.

💡Sample Preparation

Sample preparation involves the steps taken to ready the milk for titration, including measuring out the correct volume of milk and diluting it with distilled water. In the video, this step is critical to ensure that the titration process is accurate and that the results reflect the true acidity of the milk sample.

💡Conical Flask

A conical flask, also known as an Erlenmeyer flask, is a common laboratory glassware used in titrations. In the video, the milk sample is placed in a conical flask for titration. The shape of the flask allows for easy mixing and swirling of the solution, ensuring a uniform reaction during titration.

💡Burette

A burette is a graduated glass tube with a tap at one end, used to dispense precise volumes of a liquid, especially in titrations. In the video, the burette is filled with 0.1 normal sodium hydroxide solution, and its readings are used to calculate the volume of sodium hydroxide added during the titration process, which is essential for determining the milk's acidity.

💡Lactic Acid

Lactic acid is the primary acid found in milk, resulting from the fermentation of lactose by bacteria. The video's goal is to measure the milk acidity as a percentage of lactic acid, which is an indicator of the milk's freshness. Higher levels of lactic acid can indicate spoilage or bacterial growth in the milk.

💡Calculation

Calculation refers to the mathematical process of determining the acidity of the milk sample based on the titration data. In the video, this involves using the final burette reading, the sample volume, and the milk's density to compute the acidity as a percentage of lactic acid. Accurate calculations are crucial for the validity of the experiment's results.

Highlights

Introduction to the experiment to determine the milk acidity or titratable acidity.

Overview of the steps involved: chemical preparation, milk density determination, sample preparation, titration, and calculation.

Mention of necessary tools and chemicals: balance machine, burette with stand, conical flask, pipette with filler, 0.1 normal sodium hydroxide solution, and phenolphthalein indicator solution.

Preparation of 0.1 normal sodium hydroxide solution by dissolving 4 grams of sodium hydroxide pellets in 900 ml distilled water and making up the volume to 1000 ml.

Instruction to standardize the sodium hydroxide solution before use.

Preparation of phenolphthalein indicator by dissolving 2 grams of fenugreek powder in 100 ml ethanol.

Reminder to check the video link for milk density determination, provided in the description.

Sample preparation by taking 10 ml of milk in a conical flask.

Adding 10 ml of distilled water to the milk sample and shaking it for proper mixing.

Adding a few drops of phenolphthalein indicator solution to the sample.

Filling the burette with 0.1 normal sodium hydroxide solution and noting the initial burette reading.

Starting the titration with vigorous agitation of the flask.

Stopping the titration when the solution changes color to light pink.

Noting the final burette reading to calculate the acidity of the milk sample.

Final calculation showing the acidity value of the milk sample as 0.131% lactic acid.