Setting up and Performing a Titration

Summary

This video, presented by Jared Hyman, an assistant professor of chemistry, provides a detailed guide on the proper technique for performing a titration. It covers essential equipment, such as burettes, pipettes, and Erlenmeyer flasks, and highlights the step-by-step process to accurately determine the concentration of an unknown solution by using a titrant. Key tips include preparing the burette, ensuring precise volume readings, and correctly identifying the endpoint using indicators. The video also emphasizes practicing titrations and using triplicate measurements for accurate results.

Takeaways

• 🧪 The purpose of titration is to determine the concentration of an unknown solution (analyte) by adding a chemical with a known concentration (titrant).
• 🔬 Titration requires key equipment such as a burette, ring stand, burette clamp, Erlenmeyer flask, volumetric pipette, pipette bulb, wash bottle, and an indicator.
• 🧯 A burette is used to add titrant to the analyte and has a stopcock to regulate the flow of liquid.
• 🔍 It is important to read the burette volume from the bottom of the meniscus at eye level for accuracy.
• 📊 Record the volume to the nearest hundredth of a milliliter for precise measurement.
• 🌡️ The first titration is often an estimate to get a rough idea of the titrant volume needed.
• ⚠️ When nearing the endpoint, titrant should be added slowly to avoid passing the endpoint.
• 🔄 The desired endpoint is indicated by a faint, pale color in the analyte, not a deep or dark color.
• 📋 Titrations are usually performed in triplicate, and the average volume of titrant is used for calculations.
• 🧫 The second video in the series will explain how to determine the concentration of an unknown acid using a known base.

Q & A

What is the purpose of titration?

The purpose of titration is to quantitatively determine the concentration of an unknown solution, commonly called the analyte, by adding a known volume of a chemical with a known concentration (the titrant) until the endpoint is reached.

What equipment is included in Carolina's complete burette assembly kit?

Carolina's complete burette assembly kit includes a burette, a ring stand, and a burette clamp.

Why is a burette used in titration, and how is it designed?

A burette is used to add titrant in a controlled manner during titration. It is a long, narrow, graduated tube with a stopcock to regulate the flow of liquid. The markings on the burette are reversed, with the lowest numbers at the top and the highest at the bottom.

Why is an Erlenmeyer flask recommended for titrations?

An Erlenmeyer flask is recommended for titrations because its shape allows for more vigorous swirling than other glassware like beakers, which helps mix the solution thoroughly while minimizing spill hazards.

What is the role of the indicator in a titration?

The indicator is added to the analyte to signal the endpoint of the titration. It changes color when the chemical reaction between the titrant and analyte is complete.

What precautions should be taken when preparing the burette for titration?

Before titration, the burette should be rinsed with deionized water and then with a small amount of titrant. It's important to check for air bubbles, ensure the liquid doesn't stick to the walls, and mount the burette vertically for accurate measurements.

Why is it unnecessary to fill the burette exactly to the zero mark?

It is unnecessary to fill the burette exactly to the zero mark as long as there is sufficient titrant to complete the titration. The starting volume is recorded, and the titration is based on the volume dispensed rather than the initial level.

How should the volume be read from the burette?

The volume should be read from the bottom of the meniscus at eye level. It is important to record the volume to the nearest hundredth of a milliliter, estimating one decimal place beyond the smallest graduation.

Why is the first titration considered an estimate?

The first titration is considered an estimate because it helps to determine the approximate volume of titrant needed. This allows for more precise adjustments in subsequent titrations to avoid surpassing the endpoint.

What is the desired appearance of the analyte at the endpoint of titration?

At the endpoint of titration, the analyte should appear as a pale, faintly colored solution. A darker color indicates an excess of titrant has been added.

Outlines

00:00

🧪 Introduction to Titration and Necessary Equipment

This section introduces the viewer to Jared Hyman, an assistant professor of chemistry at Elon University, who will demonstrate proper titration techniques using the Complete Single Burette Assembly Kit from Carolina Biological Supply Company. The purpose of titration is to measure the concentration of an unknown solution by adding a known solution (the titrant). The video will review essential equipment needed for titration, such as the burette, ring stand, burette clamp, Erlenmeyer flask, volumetric pipette, wash bottle, and other materials. Specific attention is given to the setup of the burette, including its proper positioning and the importance of using deionized water to rinse equipment before use.

05:00

⚗️ Setting Up and Performing a Titration

This section describes the procedure for preparing the burette and performing a titration. After ensuring the burette is free of air bubbles and filled with titrant, the Erlenmeyer flask is placed under the burette to allow a few milliliters of titrant to release. Key steps include recording the starting volume of the titrant and reading the concave meniscus accurately. The importance of precision, including the correct number of significant figures in measurements, is emphasized. The viewer is also guided on how to use a volumetric pipette to transfer the analyte to the flask, add an indicator, and operate the burette efficiently by swirling the flask during titrant addition. The first titration is typically an estimate, and the endpoint is determined by color change.

🎨 Refining Titration Technique to Reach the Endpoint

This paragraph explains how to refine the titration process to accurately determine the endpoint. It describes how to adjust the addition of titrant more slowly as the color change becomes visible in the analyte. The video guides the viewer through slowing down titrant addition to a drop-wise rate as the endpoint approaches. The indicator will show a faint color at the endpoint, signaling the reaction's completion. The process of adding titrant drop by drop, rinsing, swirling, and recording the final volume until the endpoint is reached is repeated if necessary. Typically, titrations are performed in triplicate, and the average titrant volume is used for calculations. Finally, viewers are encouraged to watch the second video in the series for determining the concentration of an unknown acid using a base of known concentration.

Keywords

💡Titration

Titration is a laboratory technique used to determine the concentration of an unknown solution, known as the analyte, by adding a solution with a known concentration, called the titrant. In the video, the process of titration is demonstrated step-by-step, with a focus on how to use a burette to slowly add titrant until the reaction reaches an endpoint, indicated by a color change.

💡Burette

A burette is a long, graduated glass tube with a stopcock at the bottom, used to precisely dispense titrant in a titration. In the video, the burette is mounted on a ring stand and is used to add a known volume of titrant into the analyte. The video emphasizes how to read the volume on the burette accurately and how to avoid air bubbles.

💡Analyte

The analyte is the unknown solution in a titration whose concentration is being determined. The video explains how the analyte is placed in an Erlenmeyer flask and mixed with a few drops of an indicator. The titrant is then added from the burette until the analyte reaches a specific color change, indicating the endpoint.

💡Titrant

The titrant is a solution with a known concentration that is added to the analyte during a titration. The purpose of adding the titrant is to react with the analyte until the endpoint is reached. In the video, the titrant is placed in the burette and gradually added to the analyte while swirling the flask.

💡Endpoint

The endpoint in a titration is the point at which the reaction is complete, often indicated by a color change in the solution due to the presence of an indicator. In the video, reaching the endpoint is critical to determining the exact volume of titrant required to neutralize the analyte. The endpoint is reached when the analyte maintains a faint, pale color.

💡Indicator

An indicator is a chemical that changes color when the titration reaction is complete. In the video, a few drops of indicator are added to the analyte in the Erlenmeyer flask, and the color change helps identify when the endpoint is reached. The video demonstrates how the color change occurs gradually as titrant is added.

💡Meniscus

The meniscus is the curved surface of a liquid in a tube, caused by surface tension. The video stresses the importance of reading the burette at eye level to accurately measure the volume of titrant by observing the bottom of the meniscus. Correctly reading the meniscus ensures precise titration results.

💡Volumetric Pipette

A volumetric pipette is used to accurately transfer a specific volume of analyte into the flask during titration. In the video, the instructor demonstrates how to use the pipette with a pipette bulb to transfer the analyte into the Erlenmeyer flask for the titration process, ensuring precise measurements.

💡Stopcock

The stopcock is a valve located at the bottom of the burette that controls the flow of titrant into the analyte. In the video, the stopcock is turned to allow a controlled flow of titrant into the flask. The instructor advises practicing with the stopcock to regulate the titrant flow, especially as the endpoint approaches.

💡Erlenmeyer Flask

The Erlenmeyer flask is a conical-shaped flask used during titration to hold the analyte. The video highlights the flask’s shape, which allows for vigorous swirling of the solution without the risk of spilling. This makes the Erlenmeyer flask ideal for titration experiments, as swirling is necessary to mix the analyte with the titrant effectively.

Highlights

Introduction to titration techniques using Carolina's complete single burette assembly kit.

Purpose of titration: determining the concentration of an unknown solution by adding a known volume of titrant.

Key equipment includes a burette, ring stand, burette clamp, Erlenmeyer flask, volumetric pipette, pipette bulb, and a wash bottle with deionized water.

Proper setup involves mounting the burette vertically and ensuring the stopcock is closed before filling with titrant.

Important laboratory practice: rinse the burette thoroughly with deionized water and titrant to avoid liquid clinging to the walls.

Explanation of how to properly read the burette by observing the meniscus at eye level and recording to the nearest hundredth of a milliliter.

Instructions for transferring the analyte to the flask using a volumetric pipette and adding an indicator.

Practice turning the burette stopcock to control the titrant flow while swirling the flask to mix the solution.

The first titration is typically an estimate to help determine the approximate volume of titrant needed.

Slow down titrant addition when the color flashes begin to appear to avoid overshooting the endpoint.

Desired endpoint is indicated by a pale, faintly colored analyte solution.

Titrations are typically performed in triplicate, and the average volume of titrant is used for final calculations.

Procedure to reach endpoint: add titrant drop-wise while swirling until a faint color persists.

Proper titration technique minimizes risk of passing the endpoint and ensures accurate results.

Follow-up video focuses on determining the concentration of an unknown acid solution using a base of known concentration.

Transcripts

[Music]

hi I'm Jared Hyman an assistant

professor of chemistry at Elon

University today we will be discussing

the proper titration technique using the

complete single burette assembly kit

available from Carolina's biological

supply company this is the first in a

two-part video series on titration the

purpose of a titration is to

quantitatively determine the

concentration of an unknown solution

commonly called the titrant

or analyte by adding a volume of a

chemical with a known concentration

called the titrant to mark the endpoint

of a titration an indicator is added to

the analyte let's review some of the

equipment that's needed for a titration

carolina's complete burette assembly

contains the basic equipment to get you

started

including a burette ring stand and a

burette clamp a burette is a long narrow

graduated tube used to add titrant it

has a stopcock

to regulate the flow of liquid notice

that the markings on the burette go from

lowest at the top to highest at the

bottom the ring stand and burette clamp

are used to mount and secure your

burette other materials you will also

need include a small funnel to help you

fill the burette a 125 milliliter

Erlenmeyer flask which works best for

titrations the shape of the flask allows

for more vigorous swirling than a beaker

or other glassware and minimizes spill

hazards a volumetric pipette and pipette

bulb to transfer a known volume of

analyte to the flask a wash bottle

filled with deionized water a beaker or

flask of titrant and of analyte

indicators selected for your reaction a

reading card to help read the meniscus

and a sheet of white paper to help

visualize the endpoint to prepare your

burette for the titration it is good

laboratory practice to rinse your

burette thoroughly with deionized water

then with a small amount of titrant

after each rinse open the stopcock to

allow the liquid to drain at the bottom

if there is a lot of liquid clinging to

the walls of the burette then thoroughly

clean your burette and

the rinse process the accuracy of this

technique is dependent on the titrant

flowing into the flask and not sticking

to the walls of the burette mount

burette in the clamp making sure it is

positioned vertically and there is

enough room to position your flask

underneath the tip check to see that the

stopcock is in the close position insert

the funnel into the top of the burette

and fill with titrant almost to the top

filling exactly to the zero mark is not

necessary but you do need sufficient

titrant to complete the reaction check

the column for air bubbles and gently

tap to free them from the sidewalls

remove the funnel place the Erlenmeyer

flask under the tip and open the

stopcock to allow a few milliliters of

titrant to flow through releasing any

trapped air rinse the tip of the burette

with water empty the liquid into a waste

container and thoroughly rinse the flask

it is not necessary to dry the flask

record your starting volume it is

important to accurately read the volume

on the burette first note that the

liquid forms a concave meniscus because

the water pulls itself up the sidewalls

of the glass you should read the volume

from the bottom of the meniscus at eye

level secondly it is important to read

your volume to the correct number of

significant figures this burette

indicates volume to the nearest point 1

milliliters with any graduated glassware

record the volume to one additional

decimal place beyond the smallest

graduation in this case record the

volume to the nearest hundredth of a

milliliter estimating the final place

use the volumetric pipette to transfer

the analyte to the flask add a few drops

of indicator to the flask and swirl

place the flask under the tip of the

burette record this volume placing a

piece of white paper under the

Erlenmeyer flask may make it easier to

detect the color change operating the

burette requires two hands one hand

turns the stopcock while the other hand

swirls the flask practice turning the

stopcock a few times to familiarize

yourself with how quickly the flow

starts and stops it is common laboratory

practice that the first titration is an

estimate open up the stopcock and allow

the titrant to enter the flask quickly

continuously swirl the flask as the

volume of titrant in the flask increases

the color of the indicator appears then

disappears as you swirl when the analyte

becomes a colored solution close the

stopcock record the final volume of the

burette subtract the initial volume from

this final volume to get the estimated

volume of titrant needed for this

titration knowing the volume that is a

little past the endpoint subtract 5

milliliters from that number to get the

amount of titrant that can be safely

added before a slower addition is

required as the estimate titration shows

a dark colored solution indicates an

excess of titrant has been added the

desired endpoint is a pale faintly

colored analyte to reduce the risk of

passing the endpoint slow down the

addition of titrant when flashes of

color begin to appear in the analyte

adjust the stopcock to slow the flow of

titrant to a drop-wise rate continue to

swirl the flask with one hand and keep

the other hand ready to close the

stopcock when you notice the indicator

taking longer to fade close the stopcock

rinse the tip of the burette with

deionized water and swirl the flask

record the final volume on the burette

if the analyte remains faintly colored

then you have reached the end point if

the analyte is still colorless then

repeat these steps add a drop rinse

swirl and record until a faint color

persists typically titrations are

performed in triplicate

use the average volume of the titrant

required to reach the end point for any

calculations you now know how to

properly perform a titration be sure to

check out the second video in this

series in that video we will go over the

proper procedure for determining the

concentration of an unknown acid

solution using a base of known

concentration Carolina has everything

you need for your chemistry lab visit us

at Carolina chemistry comm to see our

complete line of products and kits for

chemistry

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