Proper use of a buret for a titration procedure

Summary

This video offers a detailed guide on using a buret for titration experiments. It emphasizes the importance of cleaning the buret, filling it with titrant solution, and performing the titration with precision. The video demonstrates how to accurately read the meniscus, use a reading card for better visibility, and estimate the endpoint by observing color changes with phenolphthalein as an indicator. It also advises on conducting multiple trials for consistency and accuracy in recording data.

Takeaways

• 🔍 Always ensure your buret is clean before starting a titration experiment.
• 💧 Rinse the buret with deionized water to avoid contamination.
• 🧼 Use detergent and water with a long-handled brush to clean the buret if water beads are observed.
• 🏺 Pour deionized water into the buret using a beaker, not directly from the faucet.
• 📌 Securely attach the buret to a stand with a clamp to prevent movement during titration.
• 🧪 Use sodium hydroxide as a titrant and phenolphthalein as an indicator for titrating acetic acid.
• 💧 Rinelyou the buret with the titrant solution multiple times before starting the titration.
• 🌡️ Check the initial liquid level in the buret and ensure it's below the zero mark.
• 📏 Use a reading card to accurately estimate the meniscus position on the buret scale.
• 📝 Record the initial and final readings of the buret to the nearest hundredth of a milliliter.
• 🔬 Practice estimating the meniscus position to improve accuracy and consistency in titration results.

Q & A

What is the first step to prepare a buret for titration?

The first step is to ensure that the buret is clean and rinse the inside with deionized water.

How do you know if the buret is clean after rinsing?

If the water sheets down the side of the glass evenly without holding droplets of water, then the buret is considered clean.

What should you do if the buret holds droplets of water after rinsing?

If the buret holds droplets of water, it should be cleaned with detergent and water using long-handled brushes.

How should you rinse the buret after using detergent?

Rinse the buret thoroughly first with tap water and then with deionized water.

What is the recommended method to fill the buret with solution?

Use a beaker to pour the solution into the top of the buret instead of holding the opening under the faucet.

Why is it important to secure the buret with a clamp?

Securing the buret with a clamp ensures it is firmly in place and prevents it from moving during the titration process.

What is the purpose of rinsing the buret with the titrant solution before titration?

Rinsing the buret with the titrant solution ensures that any residual water does not dilute the titrant, affecting the accuracy of the titration.

Why is it necessary to coax any bubbles out of the tip of the buret?

Bubbles in the tip can cause an inaccurate reading and affect the delivery of the titrant, thus it's important to remove them for precise titration.

What is the purpose of using a reading card when measuring the volume in the buret?

A reading card helps to clearly see the meniscus against the white background, providing a more accurate reading of the volume.

How should you position your eyes when reading the meniscus?

Your eyes should be positioned in the same plane as the tangent drawn to the bottom of the meniscus for an accurate reading.

What is the significance of recording the initial reading in each titration?

Recording the initial reading is crucial for determining the volume of titrant used and calculating the concentration of the analyte.

How can you estimate the endpoint of the titration?

You can estimate the endpoint by conducting a preliminary trial to find the approximate endpoint, then conducting subsequent trials more carefully from a point close to the end.

What is the Troop endpoint and how is it determined?

The Troop endpoint is the first faint color that remains after 15 seconds of stirring, indicating the end of the titration.

Outlines

00:00

🧪 Proper Buret Usage for Titration

This paragraph outlines the correct procedure for using a buret in a titration experiment. It emphasizes the importance of cleaning the buret with deionized water and detergent, using a brush to scrub the interior. The buret should be filled with a beaker rather than directly from a faucet, and secured with a clamp. The paragraph details the process of titrating acetic acid with sodium hydroxide using phenolphthalein as an indicator. It advises on how to fill the buret, remove air bubbles, and start the titration. The importance of accurate readings and the use of a reading card for precise meniscus observation is highlighted. The goal is to achieve consistent and accurate data to the nearest hundredth of a milliliter.

05:02

🎨 Capturing Color Change in Titration

The second paragraph focuses on the technique for accurately capturing the color change during the endpoint of a titration. It suggests running the first trial quickly to estimate the endpoint and then conducting subsequent trials more carefully. The paragraph provides a method for observing the color change by slowly opening the stopcock and using a wash bottle to rinse the droplet into the reaction flask. It clarifies that adding small amounts of water does not affect the endpoint appearance and defines the Troop endpoint as the first faint color that persists after 15 seconds of stirring. The paragraph concludes with instructions to carefully read and record the ending volume to the nearest hundredth of a milliliter.

Keywords

💡Buret

A buret is a piece of laboratory glassware that is used to dispense liquids in a controlled and precise manner. It is typically used in titration experiments to measure volumes of solutions accurately. In the video, the buret is central to the procedure, as it is used to add a solution drop by drop to another solution until a chemical reaction is complete, indicated by a color change.

💡Deionized Water

Deionized water is water that has had most or all of its impurities and ions removed, making it highly pure. In the context of the video, deionized water is used to rinse the buret before use to ensure that any residual contaminants do not affect the titration results.

💡Titration

Titration is a common laboratory procedure used to find the concentration of an unknown solution by reacting it with a solution of known concentration. The video script describes a titration experiment where sodium hydroxide is used to titrate acetic acid, and the endpoint is indicated by a color change.

💡Phenolphthalein

Phenolphthalein is a pH indicator used in titration to signal the endpoint of the reaction. It is colorless in acidic solutions and turns pink in basic solutions. In the video, phenolphthalein is used to indicate when the titration of acetic acid with sodium hydroxide is complete.

💡Stopcock

A stopcock is a valve used to control the flow of liquid through the buret. It is crucial in titration for adding the titrant at a controlled rate. The video mentions ensuring the stopcock is closed before adding the titrant and using it to introduce liquid into the bottom of the buret.

💡Meniscus

The meniscus is the curved surface of a liquid in a container, resulting from surface tension. In the video, the meniscus is used to read the volume of liquid in the buret, with the script providing instructions on how to estimate its position accurately.

💡Reading Card

A reading card is a tool used to improve the accuracy of readings in a buret by providing a contrasting background against the meniscus. The script describes using a reading card to get a clear outline of the meniscus against a white background, which helps in reading the volume more accurately.

💡Endpoint

The endpoint of a titration is the point at which the reaction between the two solutions is complete. The video script explains that the endpoint is signaled by a color change that persists for 15 seconds after stirring, indicating that no more titrant is needed.

💡Titration Flask

A titration flask is a container used to hold the solution being titrated. In the video, the titration flask is placed under the buret to ensure that the titrant is added directly to the solution being tested, minimizing the chance of losing any drops.

💡Waste Beaker

A waste beaker is used to collect waste liquid, such as rinse water from the buret. The script mentions pouring rinse water from the buret into a waste beaker to prevent contamination of the titration solution.

💡Dust Cap

A dust cap is a protective cover used to keep the opening of the buret clean from dust and other contaminants. The video script suggests adding a dust cap after the initial filling of the buret to prevent any foreign particles from entering and affecting the titration.

Highlights

Ensure that the buret is clean before starting the titration experiment.

Rinse the buret with deionized water to ensure even flow.

Clean the buret with detergent and water if water droplets hold on the glass.

Use long-handled brushes to clean the inside of the buret.

Rinse the buret thoroughly with tap water followed by deionized water.

Pour deionized water into the buret using a beaker instead of holding it under the faucet.

Securely attach and lock the buret into place with a clamp.

Use sodium hydroxide to titrate acetic acid with phenolphthalein as the color indicator.

Ensure the stopcock is closed before pouring the titrant solution into the buret.

Rinse the buret with the titrant solution multiple times before starting the titration.

Pour the liquid out into a waste beaker to prepare for titration.

Refill the buret for titration and coax any bubbles out of the tip.

Position a beaker to catch waste solution below the buret tip.

Estimate the meniscus position on the graduated scale for accurate readings.

Use a reading card to help determine the meniscus position.

Ensure consistent positioning of the reading card and eyes for accurate readings.

Estimate the meniscus position to the nearest hundredth of a milliliter.

Record the initial reading of each titration for consistency.

Transfer the sample to the titration flask carefully to avoid losing drops.

Run multiple trials with the same sample for consistent results.

Use a technique to capture the color change within a fraction of a drop at the endpoint.

The endpoint is the first faint color that remains after 15 seconds of stirring.

Record the ending volume to the nearest hundredth of a milliliter in the laboratory notebook.

Transcripts

this video will cover the proper use of

a buret look elsewhere for specific

information about the chemistry of your

particular type of titration experiment

before you begin ensure that your buret

is clean rinse the inside with some

deionized water the water should sheep

down the side of the glass evenly if the

glass holds droplets of water as shown

here then clean the buret with detergent

and water use the long handled brushes

that extend the full length of the

Barrette put some detergent and water on

the brush and scrub the inside

rinse the buret thoroughly first with

tap water and then with deionized water

use a beaker to pour into the top of the

buret rather than trying to hold the

opening of the buret under the faucet

attach a buret clamp firmly to the stand

and lock the buret into place

in this demonstration we will be using

sodium hydroxide to titrate a solution

of acetic acid using phenolphthalein as

a color indicator of the endpoint of the

titration

be sure that the stopcock is closed and

then pour the titrant solution slowly

into the open end

rinse the buret with five to ten

milliliter portions

two or three more times

rotate the buret slowly as you pour the

liquid out into a waste beaker

now refill the briaret for the titration

place a beaker for catching waste

solution below the buret tip use several

quick twists of the stopcock valve to

introduce liquid into the bottom of the

bread and coax any bubbles out of the

tip

if necessary bring the liquid level back

near the top you don't have to start

exactly at the zero Mark the meniscus

must however begin somewhere below the

line associated with zero if you've used

a funnel to pour into the buret then

remove it now so it does not drip into

the buret after you've started your

titration that would lead to an error

you may also want to add a dust cap

estimate where the bottom of the

meniscus is on the graduated scale you

may find it helpful to use a reading

card a reading card is merely a colored

rectangle on a white background by

bringing the rectangle up just below the

meniscus colored light is reflected off

the curved surface to give a distinct

outline against the white background if

you use this method be careful about

keeping the rectangle at a consistent

distance from the bottom of the meniscus

each time you read the meniscus may

appear to move as the rectangle moves

equally important is positioning your

eyes so that it is it's in the same

plane as the tangent drawn to the bottom

of the meniscus here the position of the

meniscus is between the zero and the one

milliliter Mark the shorter lines that

do not go all the way around the buret

are associated with intervals of 0.1

milliliter

in this case the meniscus appears to be

between the seventh and the eighth marks

so its position is at least 0.7

milliliters we can estimate the fraction

of the gap between the nearest lines

spanned by the bottom of the meniscus

here it appears to be a little bit less

than halfway perhaps 40 percent of the

interval in that case we estimate this

position of this meniscus at the start

of this titration to be about

0.74 milliliters

this last digit is a guess but with a

little practice you can learn to be very

consistent and obtain reproducible and

accurate data to the nearest hundredth

of a milliliter

that should be your goal in your work

today be sure to record your initial

reading in each of your titrations

we're ready now to transfer the sample

to our titration flask in this

demonstration we are using acetic acid

as a sample

we count the number of drops of

indicator that are added so that our

results will be as consistent as

possible from run to run we place the

titration flask under the buret point so

that the buret is slightly below the rim

of the flask this minimizes the chance

for losing an errant drop

we begin adding titrant if we have a

good idea roughly where the end of the

titration will occur then we can save

some time by running the titrant into

the flask to within a milliliter of two

of the expected endpoint it is common

practice to run multiple trials with

portions of the same sample so it is

good strategy to run one trial very

quickly really to find out where the

approximate endpoint is

the next few trials can be done

carefully from a point very close to the

end

the first trial does not need to be

averaged with the more carefully

obtained data close to the endpoint the

color disperses more gradually

here is a technique for capturing the

color change to within a fraction of a

drop of the end point open the stopcock

very slowly only part way allow a

droplet to grow about half its full size

then use the wash bottle to rinse the

drop down into the reaction flask

adding small amounts of water does not

change the appearance of the end point

The Troop endpoint is in this case the

first faint color that remains after 15

seconds of stirring

finally carefully read the ending volume

and record it to the nearest hundredth

of a milliliter in your laboratory

notebook