Acid-Base Titration Lab

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Questions and Answers

What is the colored part of the citrus peel called?

Endocarp

Albedo

Mesocarp

Flabelo (correct)

What is the main component of the mesocarp?

Cellulose (correct)

Fats

Carbohydrates

Proteins

What is the purpose of heating the sample in the titration process?

To create a chemical reaction

To measure the pH

To concentrate the sample

To eliminate the antiferment (correct)

What is the equation used to calculate the acidity percentage?

((ml.gastados de NaOH 0.1 N) (0.009)) / (ml.de muestra) x 100 Signup and view all the answers

What is the equivalent of citric acid for 0.1N NaOH?

0.0064 Signup and view all the answers

What is the edible part of the citrus fruit?

Endocarp Signup and view all the answers

Why is it necessary to perform dilutions when expressing the results as citric acid hydrate?

To obtain accurate results Signup and view all the answers

What is the purpose of the titration process?

To calculate the acidity percentage Signup and view all the answers

What are the indicative parameters of poor milk quality?

pH level and bacterial count Signup and view all the answers

What is the purpose of the titrations in laboratory chemistry?

To determine the concentration of an acid or a base in a solution Signup and view all the answers

What is the normal value of protein in milk in Mexico?

3.5% Signup and view all the answers

What is the pH range of fresh milk?

pH 6.5 to 6.7 Signup and view all the answers

What is the function of fenolftaleína in the titration of milk?

It is an indicator used to detect the endpoint of the titration Signup and view all the answers

What are the main lipids present in emulsion in cow milk?

Triglycerides and cholesterol Signup and view all the answers

What is the term for the acidity of milk that is due to the presence of phosphates, proteins, citrates, and CO2?

Acidity aparente Signup and view all the answers

What is the primary purpose of analyzing milk quality?

To ensure food safety and quality Signup and view all the answers

What can affect the quality of milk?

All of the above Signup and view all the answers

What is the term for the difference between the titrable acidity and the apparent acidity of milk?

Acidity real Signup and view all the answers

What is the minimum acidity percentage of milk that must be rejected after detecting its odor?

0.18% Signup and view all the answers

What is the main consequence of consuming poor-quality milk?

Foodborne illness Signup and view all the answers

What is the primary component of milk?

Water Signup and view all the answers

What is the characteristic smell of sour milk due to?

The subproducts of lactate fermentation Signup and view all the answers

What is the purpose of milk emulsion?

To stabilize fat and water Signup and view all the answers

What is the purpose of the Universal Support in the laboratory setup?

To support the equipment Signup and view all the answers

What is the purpose of determining the lactose percentage in milk?

To detect if the milk has been adulterated with water or if it comes from cows with mastitis Signup and view all the answers

What is the name of the method used to determine the lactose percentage in milk?

Fehling method Signup and view all the answers

What is the concentration of acid benzoic in the solución acuosa used to prepare the lactose standard solution?

2% w/v Signup and view all the answers

What is the volume of the volumetric flask used in the experiment?

100 ml Signup and view all the answers

What is the purpose of the reactivo Fehling A and B?

To react with the lactose and indicate the endpoint of the titration Signup and view all the answers

What is the type of lactose used to prepare the standard solution?

Lactose anhydrate Signup and view all the answers

What is the indicator used in the titration process?

Azul de metileno Signup and view all the answers

What is the amount of lactose anhydrate dissolved in 1 liter of solución acuosa to prepare the standard solution?

10 grams Signup and view all the answers

What is the objective of this laboratory practice?

To analyze the Vitamin C content in citrus fruits Signup and view all the answers

What is the name of the acid used in this laboratory practice?

Ascorbic acid Signup and view all the answers

What is the role of starch in this laboratory practice?

As an indicator Signup and view all the answers

What is the function of Vitamin C in the human body?

To control some chemical reactions Signup and view all the answers

Which of the following is not a substance used in this laboratory practice?

Sodium Chloride Signup and view all the answers

What is the purpose of using Potassium Iodide in this laboratory practice?

To react with Ascorbic acid Signup and view all the answers

What is the concentration of Sulfuric acid used in this laboratory practice?

0.3 M Signup and view all the answers

What type of fruits are used in this laboratory practice?

Citrus fruits Signup and view all the answers

Study Notes

Acidity of Milk

Milk is amphoteric, meaning it can exhibit both acidic and basic properties.
Fresh milk has a pH of 6.5-6.7, making it slightly acidic.
When titrated with an alkaline solution using phenolphthalein as an indicator, milk yields an average acidity of 0.14% expressed as lactic acid, known as apparent acidity.
This acidity is due to the presence of phosphates, proteins, citrates, and CO2, not the lactic acid produced by microbial contamination.
The difference between titratable acidity and apparent acidity is called real acidity.
This test is valuable for classifying milk, and milk with acidity above 0.18% should be rejected.

Determination of Lactose

The objective is to determine the percentage of lactose (disaccharide) in milk using the Fehling method.
The reactants used are Fehling's A and B solutions.
The procedure involves titrating a milk solution with the Fehling's solutions to determine the amount of lactose in grams equivalent to 1 ml of Fehling's solution.

Vitamin C Analysis

Vitamin C is also known as ascorbic acid.
It is an essential nutrient in the human diet and plays a crucial role in enzyme systems.
Vitamin C is present in various foods, especially citrus fruits.
The objective is to analyze the vitamin C content in citrus fruits using a semiquantitative method.
The reaction between ascorbic acid and iodine is used, with starch as an indicator.

Laboratory Equipment and Materials

The laboratory equipment used includes:
- Pipettes (10 ml, 25 ml)
- Burette
- Volumetric flask (100 ml)
- Erlenmeyer flask
- Measuring cylinder
- Stirring rod
- Bunsen burner
The materials used include:
- Sodium hydroxide (0.1 N)
- Phenolphthalein (1%)
- Distilled water
- Milk and cream samples
- Lactose
- Fehling's A and B solutions
- Starch
- Iodine
- Potassium iodide

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Description

A laboratory experiment on acid-base titration, involving the use of burettes, pipettes, and reagents to determine the concentration of an acid or base in a solution. This quiz is based on the procedures and reactions in the lab.