Titration is an analytical method that can be used to determine the amount of an unknown present in a sample. Titration is the process of adding a reagent solution of known concentration (the titrant) to an unknown until all of the substance of interest is used up. In order for a titration to be useful for analysis a number of different conditions need to be met. Among these are: a reaction with known ratios of reactants and products; stable reagents for the analysis; and a method for determining when the reaction is complete. This lab involves the determination of amount of acetic acid in vinegar by titrating the vinegar sample with a standardized solution of sodium hydroxide. Safety Precautions Sodium hydroxide is a caustic base that which will cause chemical burns upon exposure. Any excess should be disposed of down the drain with sufficient water to ensure dilution.Acetic acid (vinegar) is a dilute acid solution and relatively non-toxic. Any excess should be disposed of down the drain with sufficient water to ensure dilution.Phenolphthalein is non-toxic in small doses, but does act as a strong laxative if ingested. Any spills should be carefully wiped up and disposed of properly.
ProcedureStudents must read “TECHNIQUE 3: BURETS” prior to coming to class to perform this lab. The instructor will demonstrate or discuss the proper set up of the burets and what the end point will look like.
1. Use a 10 mL graduated cylinder to add 10.0 mL of vinegar into three separate 250 mL Erlenmeyer flasks. Add 15 mL of de-ionized water to each one using a graduated cylinder.
2. Add 3-4 drops of phenolphthalein indicator to each flask.
3. Clean and fill a buret with the standardized sodium hydroxide solution provided in the lab. Use a 100mL beaker to transfer the solution from the bottle to the buret. Record the initial and final volume of solution in the buret (at the start and end of the titration)
4. Titrate each flask until the phenolphthalein just turns pink.
5. Calculate the amount of acetic acid present in the vinegar.
6. Compare to the value given on the vinegar bottle.
DataTable 1: Titration of vinegar using standardized sodium hydroxideTrial Initial volume Final volume Titrated volume Observations1 0 45.1 45.1 Dark pink2 0 44.4 44.4 V Light pink3 0 43.1 43.1 V Light pink
Calculations & ResultsThe density of vinegar is approximately 1.00 g/mL so 10 mL of vinegar would have a weight of approximately 10 g.
% acetic acid = (MNaOH) (VNaOH) (60.0 grams acetic acid per mole) x 100 10.0 grams vinegar
Calculate the percent acetic acid of the vinegar in each of the three trials. Average the values.
Table 2: (add your own title)
Pre Lab
Purpose:
In this experiment we will determine the amount of an unknown present in a sample. Also we will determination amount of acetic acid in vinegar by titrating the vinegar sample with a standardized solution of sodium hydroxide.
Materials and Chemicals:
• Sodium hydroxide • Acetic acid (vinegar) • Phenolphthalein• 10 mL graduated cylinder• 250 mL Erlenmeyer flasks• 100mL beaker
Safety: Personal and General laboratory safety:• Never pipette anything by mouth.• Skin wear safety glasses to prevent skin exposure or face shields when working with hazardous materials and/or equipment.• Wear gloves when using any hazardous or toxic agent.• Clean up your work area before leaving.• Wash hands before leaving the lab and before eating.• Eyes Wear chemical splash goggles.• Clothing: Wear appropriate protective clothing to prevent skin exposure
acetic acid (CH3COOH) can pose serious hazards to the health. This chemical is especially dangerous when it comes in contact with either the skin or eyes. In any instance of acetic acid exposure, it is important to seek help from a medical professional right away to help prevent damaging health effects.Eye Contact: Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Cold water may be used. Get medical attention immediately. Skin Contact: In case of contact, immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Cover the irritated skin with an emollient. Cold water may be used.Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical attention immediately. Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention. Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately. Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation. WARNING: It may be hazardous to the person providing aid to give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive. Seek immediate medical attention. Ingestion: Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. Loosen tight clothing such as a collar, tie, belt or waistband. Get medical attention if symptoms appear
sodium hydroxide (NaOH) Depending on the concentration of the hydrochloric acid you are working with, accidental exposure can occur as skin contact, eye contact, ingestion or inhalation of acidic vapors. Each of these types of exposure can pose serious hazards to your health and should be managed immediately.• Skin Contact – If hydrochloric acid comes into contact with skin, flush immediately with plenty of water for at least 15 minutes, and remove any contaminated clothing. In case of serious skin contact, use water, a disinfectant soap, and anti-bacterial cream. Seek immediate medical attention.• Eye Contact – If hydrochloric acid or acidic mists get into your eyes, immediately flush with plenty of water for at least 15 minutes. Seek immediate medical attention.• Ingestion – If swallowed, do not induce vomiting. Seek immediate medical attention.• Inhalation – Move to fresh air. If breathing is difficult, give oxygen. Do not use mouth-to-mouth resuscitation if victim ingested or inhaled the substance; induce artificial respiration with a respiratory medical device. Obtain medical attentionPhenolphthalein is non-toxic in small doses but does act as a strong laxative if ingested. Any spills should be wiped up and disposed of properly.
Eyes: Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid.
Skin: Get medical aid. Flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Ingestion: Get medical aid. Wash mouth out with water.
Inhalation: Remove from exposure and move to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical aid.