Precision is critical to every chemistry lab, and a burette is one of the most important tools used for precise outcomes from experiments, particularly in chemistry titrations. Learning how to use a burette correctly, preparing the burette, and conducting titration can drastically improve the result of your titration experiment, whether you’re performing acid-base titrations or working on complex clinical analyses in a lab.

In this comprehensive guide, we will cover everything from selecting the proper burette to an overview of the titration process to maintaining your burette for long-term use.  Whether you're preparing for an experiment or reviewing titration exam questions, this guide will walk you through selecting, using, and maintaining a burette, as well as mastering titration calculations for accurate results.

What Is a Burette and Why Does It Matter?

A burette is a laboratory glassware used to measure and dispense precise amount of liquid. It’s usually a long, narrow cylinder with volume measurements printed on the side, graduated like so. A burette releases the liquid in small portions, making them ideal for use in experiments that require a lot of accuracy, like in chemistry titrations.

Understanding what titration is in chemistry class is fundamental for students and researchers, as it is a crucial analytical technique used to determine the concentration of an unknown substance.  In titrations, a solution of known concentration (the titrant) is added to a solution of unknown concentration (the analyte) in a controlled manner until the endpoint of a chemical reaction is reached, as indicated by a color change or other marker.

To make this possible you need a burette, which allow you to dispense the titrant accurately.The accuracy of a burette is crucial in titrate chemistry, ensuring that each experiment yields precise and reproducible results.

Choosing the Right Burette: Types of Burettes

1. Glass Burettes

These are glass tubes with a taper at the end. The appropriate choice depends on variables including the needed accuracy, the chemicals that you work with, and your budget. 

Class A Glass Burettes: The most precise and accurate burette found on the market. Made of high-quality borosilicate glass, they’re cast to dispense precise volumes with low margin for error. Class A burettes are perfect for analytical chemistry, where accuracy is of the essence.

Class B Glass Burettes:

Class B burettes are less accurate than their Class A counterparts, though they remain suitable for most general lab work. These are more affordable and are adequate for experiments that don’t need the extreme precision of Class A burettes.

2. Digital Burettes

As modern alternatives to glass burettes, these measuring devices are equipped with a digital display of the exact dispensed volume. Another benefit of digital burette is when you read the measurement on glass burette, there is a possibility of parallax error which can lead to human error, however; digital burettes minimise these types of human errors. They are ideal for repetitive titrations or wherever more user friendliness is required.

3. Automatic Burettes

The automatic burette is a reservoir burette used in continuous titrations; as the substance is dispensed, the burette is automatically refilled. Although slightly more expensive, they are a great option for long titrations or if multiple titrations are performed as it means you don't have to constantly refill the reaction vessel, thus saving time.

4. Specialty Burettes

Micro Burettes: Intended for precise titrations with very small volumes. They are great for experiments in which every drop matters.

PTFE (Teflon) Stopcock Burettes: With the highly chemical resistant Teflon stopcocks, these burettes are used. They are suitable for work with nasty chemicals that would etch glass stopcocks.

Get Your Burette Ready for Chemistry Titration

Your titration won't make much sense if you don't set up your burette properly, so that's the first step here. Here’s a guide that walks you through the process step by step:

Step 1: Secure the Burette

Place your burette in a burette clamp attached to a stand. Make sure it's perfectly vertical—even a slight tilt can cause inaccurate readings due to parallax error. Remember, stability and alignment are key for precise results.

Step 2: Rinse the Burette

Before dispensing solution always rinse your burette. Shower it off with distilled water to get any muck or impurities off of it. Then, rinse it with a small amount of the solution you’ll be using. This ensures that no leftover substances interfere with your results—clean glassware is essential for accurate titration.

Step 3: Fill the Burette

Carefully fill the burette with your titrant. Make sure the liquid level is slightly above the 0.00 mL mark. If you're using a funnel, remove it after filling—leaving it in place can cause extra liquid to drip in and affect your readings.

Step 4: Remove Air Bubbles

Check for air bubbles in the burette, especially near the tip. Air bubbles can throw off your measurements. To remove them, gently tap the burette or open the stopcock slightly until the bubbles escape. The burette should be completely bubble-free before you begin titrating.

Step 5: Set the Starting Point

Once the burette is bubble-free, lower the liquid level to exactly 0.00 mL by opening the stopcock and letting a small amount of titrant flow into a waste container. This gives you a precise starting point for your measurements.

Step 6: Remove the Funnel

If you filled the burette with a funnel, that funnel needs to be removed after filling the burette. Residual solution in the funnel would inadvertently flow down into the burette and introduce error into your titration.

Step 7: Log the Start Volume

Read the initial volume of your solution in the burette carefully. Always ensure that you’re at eye level with the meniscus in order to avoid parallax errors when reading the volume. This reading is important for determining the volume of titrant used.

Conducting the Titration

Now that you have your burette set up, you are about to perform the titration. Here is a simple guide to draw you through the process of titration:

Step 1: Add the Titrant

Add the titrant from the burette into the analyte slowly while continuously swirling the flask. When you're nearing the expected titration endpoint, add titrant in small increments. This prevents overshooting the reaction and potentially obtaining inaccurate results.

Step 2: Watch for the End point

The endpoint of the titration is when the indicator (probably phenolphthalein in this case) changes colour. This colour change signals that the reaction has completed. Because titration is considered complete, the endpoint must remain stable for more than 30 seconds.

3. Write Down the Final Volume

As soon you reach the endpoint, note the final volume of the titrant. This is crucial for finding out how much of titrant was processed by the reaction.

Calculating the Results

Once you have performed the titration, you can now calculate the concentration of the unknown solution. Here’s how you can do it:

Step1: Calculate the Volume of Titrant Used

Subtract that first volume from the final volume from you’re going to determine how much titrant had you used during the titration.

Step 2: Apply the Titration Formula

To determine the concentration of the unknown solution (the analyte), you can use the following equation:

The basic formula is:

Ca×Va=Cb×VbCa×Va=Cb×Vb

Where:

• CaCa is the concentration of the analyte,

• VaVa is the volume of the analyte,

• CbCb is the concentration of the titrant, and

• VbVb is the volume of the titrant used.

Using this formula, you can solve for the unknown concentration of your analyte.

How To Clean and Maintain Your Burette

After completing your experiment, it’s important to clean your burette properly for the next time you use it to ensure it will give you the correct measurements. Here's how:

• If chemicals have dried/hardened on the inside of the burette, use a burette brush to scrub the inside clean.

• After rinsing with distilled water, rinse the burette with the next solution it will contain (or a storage solution if you are putting it away thereafter).

• Let the burette air dry and make sure no moisture is left inside before you store it.

Final Thoughts: A Primer on Titration

In any chemistry laboratory, the burette is essential equipment for accurately performing titrations. Knowing the various types of burettes, their uses, and how to maintain them will help you to be accurate with your experiments—by following these steps. 

From affordable glass burettes to advanced digital and automatic models, Science Equip has a wide selection of high-quality burettes to suit all your titration requirements. Rest assured that you will discover everything that you need to complete your tests with enthusiasm with our commitment to multimedia laboratory tools.

Are you ready to take your lab work to the next level? Discover a wide range of burettes and various other precision instruments for more efficient experiments and dependable outcomes. 

Ensure you select the correct burette and follow proper procedures when setting it up; also, maintain it well to ensure accurate and repeatable results. Contact us today to find out how our products can help your work!

Reference/s:

Simply Wall St - Australian (ASX) Chemicals Industry Analysis