Woof! Argon here—your lab-loving, tail-wagging science dog—ready to help you fetch some clarity about two laboratory classics: burettes and pipettes, and a less-barked-about but important topic, glass stopcock burettes versus alkaline (PTFE stopcock) burettes. Whether you’re running a chemistry class or guiding your first titration, understanding these tools makes experiments safer, more accurate, and much more fun. Even better, my good friends at TNLab.com have all different types of burettes and pipettes to choose from so you can start making your experiments more exact!
Burettes vs. Pipettes: Same Family, Different Jobs
At first glance, burettes and pipettes both look like long, skinny tubes designed to move liquids from point A to point B. But trust me—just like a dog leash and a collar, they serve different purposes.
What Is a Burette?
A burette is a long, vertical, graduated tube with a control valve (stopcock) at the bottom. It’s designed to deliver precise, variable volumes of liquid, drop by drop.
In classroom science, you’ll most often meet burettes in titration experiments. Need to slowly add an acid to a base until the color changes? A burette is your best friend. You can start, stop, and control the flow very carefully, reading exactly how much liquid was used by comparing starting and ending volume markings.
Key burette features:
- Measures delivered volume
- Ideal for titrations and reaction monitoring
- High precision for changing volumes
- Requires careful setup and vertical mounting
What Is a Pipette?
A pipette is designed to deliver a fixed and known volume of liquid quickly and accurately. Think of it as the “fetch and deliver” star of the lab.
There are several types used in schools:
- Volumetric pipettes (one exact volume, very accurate)
- Graduated pipettes (can measure several volumes)
- Disposable plastic pipettes (less precise, great for beginners)
Pipettes shine when you need to transfer a specific amount, like 10.00 mL of solution, into a flask before starting a reaction.
Key pipette features:
- Transfers a predefined volume
- Faster than a burette
- Simpler technique
- Perfect for preparation and setup steps
Quick Paw-spective Comparison:
Stop Right There! Glass Stopcock vs. Alkaline (PTFE) Burettes
Now let’s sniff out the difference between traditional glass stopcock burettes and alkaline burettes, often called PTFE stopcock burettes.
Glass Stopcock Burettes
Classic and elegant, glass stopcock burettes use a ground-glass valve to control liquid flow. You’ll still find them in many teaching labs.
Advantages:
- Smooth, precise control when well maintained
- Made entirely of glass—great for compatibility with many reagents
- Lower cost in some school settings
Challenges:
- Need lubrication (usually grease)
- Can seize up if solutions crystallize
- Strong bases may damage the glass surface over time
- Placement alignment affects leak risk
These are fine for general classroom use, but they require careful cleaning and regular attention—something not every paw… uh, student… remembers.
Alkaline (PTFE Stopcock) Burettes
Alkaline burettes are designed specifically to handle strong bases like sodium hydroxide. Instead of glass-on-glass friction, they use PTFE (Teflon) stopcocks.
Advantages:
- Chemically resistant to alkaline solutions
- No grease needed—clean and low maintenance
- Smooth turning even after long storage
- Significantly reduced leaking and sticking
Why they matter in classrooms:
Strong bases are common in teaching labs, and PTFE stopcocks improve safety, precision, and durability—especially important when equipment is shared by many students.
Possible downside?
They tend to cost a bit more upfront, but they often last longer and save time over years of use.
Which Should You Choose for Teaching Labs?
Argon’s verdict (tail thump of approval included):
- Use pipettes when teaching accurate volume transfer and basic solution preparation.
- Use burettes when demonstrating reaction stoichiometry or teaching titration techniques.
- Choose PTFE (alkaline) burettes if strong bases are involved or maintenance time is limited.
- Glass stopcock burettes are still excellent for neutral solutions and traditional setups—just care for them well!
Final Wag
Understanding your tools is a huge part of doing good science. When students know why they’re using a burette instead of a pipette—or why one stopcock turns easier than another—they’re not just following instructions; they’re thinking like scientists.
Until next time, keep your measurements accurate, your glassware clean, and your curiosity curious.
Argon the Science Dog 🐾