---
title: "Buret — AP Chem Definition, Titrations & Exam Guide"
description: "A buret is a graduated glass tube with a stopcock that delivers precise volumes of titrant in a titration. Essential for AP Chem Topic 4.6 lab questions."
canonical: "https://fiveable.me/ap-chem/key-terms/buret"
type: "key-term"
subject: "AP Chemistry"
unit: "Unit 4"
---

# Buret — AP Chem Definition, Titrations & Exam Guide

## Definition

A buret is a long graduated glass tube with a stopcock (tap) at the bottom, used in AP Chem to deliver a precisely measured volume of titrant to an analyte during a titration, letting you find exactly how much solution was needed to reach the equivalence point.

## What It Is

A buret (also spelled burette) is the tall, skinny glass tube clamped above the flask in every [titration](/ap-chem/unit-4/intro-titrations/study-guide/8XHQYjYki6GqAcrp18I2 "fv-autolink") setup. It's marked with fine [volume](/ap-chem/key-terms/volume "fv-autolink") graduations and has a stopcock at the bottom so you can release titrant drop by drop. You read the volume before you start, read it again when the indicator changes color, and the difference tells you exactly how much titrant you delivered.

That precision is the whole point. In a titration, the titrant has a known [concentration](/ap-chem/unit-3/beer-lambert-law/study-guide/smCHzraorVz6qlWW1oeB "fv-autolink") and reacts specifically and quantitatively with the analyte. To calculate the analyte's concentration, you need to know the titrant volume to two decimal places (like 24.65 mL), and a buret is the only common piece of glassware that delivers a *variable* volume that accurately. It's the hardware that makes the math in [Topic 4.6](https://fiveable.me/ap-chem/unit-4/introduction-titration/study-guide) possible.

## Why It Matters

The buret lives in **[Unit 4](/ap-chem/unit-4 "fv-autolink"): Chemical Reactions, Topic 4.6 (Introduction to Titration)** and directly supports learning objective **[AP Chem](/ap-chem "fv-autolink") 4.6.A**, which asks you to identify the equivalence point based on the amounts of titrant and analyte. The essential knowledge is clear that the equivalence point happens when the analyte is totally consumed by the titrant. The buret is how you measure the titrant side of that equation. Stoichiometry tells you the mole ratio, but the buret reading gives you the actual moles delivered (volume × molarity). Burets also show up again whenever titrations return later in the course, especially acid-base titration curves, so knowing the apparatus cold in Unit 4 pays off twice.

## Connections

### [Equivalence Point (Unit 4)](/ap-chem/key-terms/equivalence-point)

The buret reading at the moment the [indicator](/ap-chem/key-terms/indicator "fv-autolink") changes is your endpoint volume, which approximates the equivalence point. You take that volume, multiply by the titrant's molarity to get moles, then use the mole ratio to find moles of analyte. The buret is the measurement; the equivalence point is what the measurement means.

### [Standard Solution (Unit 4)](/ap-chem/key-terms/standard-solution)

What goes inside the buret is a [standard solution](/ap-chem/key-terms/standard-solution "fv-autolink"), a titrant of precisely known concentration. The buret handles the 'known volume' half of the calculation and the standard solution handles the 'known concentration' half. Together they pin down the unknown analyte.

### [Molarity (Unit 4)](/ap-chem/key-terms/molarity)

Every titration calculation runs through moles = [molarity](/ap-chem/key-terms/molarity "fv-autolink") × volume in liters. The buret volume (say, 0.02465 L) times the titrant's molarity gives moles of titrant, which is the starting line for the entire stoichiometry problem. Sloppy buret reading means a wrong final answer, even with perfect math.

## On the AP Exam

Multiple-choice questions test whether you know what each piece of glassware does. A classic stem asks which apparatus precisely delivers the titrant (answer: the buret), or describes a student adding NaOH from a buret until an indicator changes color and asks you to name the procedure (a titration) or identify the analyte. On FRQs, the buret shows up inside lab-based prompts. The 2019 exam had a student titrating oxalic acid with dark purple KMnO₄ from a buret, and the 2021 exam built a question around determining a CuSO₄ solution's concentration experimentally. You're expected to read initial and final buret volumes from a figure, subtract to get volume delivered, convert to moles, and run the stoichiometry. You may also need to explain a procedural choice, like why a buret beats a graduated cylinder for delivering titrant (precision and drop-by-drop control near the endpoint).

## buret vs Volumetric pipet

Both are precision glassware, but they do opposite jobs. A volumetric pipet delivers one fixed volume (like exactly 25.00 mL) and is used to measure out the analyte sample. A buret delivers a variable volume that you control with the stopcock, which is what you need for titrant since you don't know in advance how much it will take to reach the endpoint. On the exam: pipet for the flask, buret for the titrant.

## Key Takeaways

- A buret is a graduated glass tube with a stopcock that delivers a precisely measured, variable volume of titrant during a titration.
- Volume delivered equals the final buret reading minus the initial buret reading, and that volume times the titrant's molarity gives moles of titrant.
- The buret holds the titrant (the solution of known concentration), while the analyte (the unknown) sits in the flask below.
- You stop adding titrant at the endpoint, the observable change (usually an indicator color change) that signals the equivalence point, where the analyte is totally consumed.
- A buret beats a graduated cylinder for titrations because it's far more precise and lets you add titrant drop by drop near the endpoint.
- Buret skills from Topic 4.6 come back whenever the exam tests titration-based lab FRQs, like the 2019 oxalic acid/KMnO₄ question.

## FAQs

### What is a buret in AP Chem?

A buret is a long graduated glass tube with a stopcock at the bottom, used to deliver a precisely measured volume of titrant during a titration. It's the core apparatus for Topic 4.6 (Introduction to Titration) in Unit 4.

### Does the buret hold the analyte or the titrant?

The titrant. The buret contains the solution of known concentration (often a standard solution like NaOH), and the analyte, the substance with the unknown concentration, sits in the flask underneath.

### How is a buret different from a pipet or graduated cylinder?

A volumetric pipet delivers one fixed volume (like exactly 25.00 mL), a graduated cylinder measures volume only roughly, and a buret delivers a variable volume with high precision. Only the buret lets you control flow drop by drop, which is why it's used for titrant.

### Is 'buret' the same as 'burette'?

Yes, they're two spellings of the same apparatus. AP Chem materials use both, so don't let the spelling throw you on a question stem.

### Do I need to read buret values on the AP exam?

Yes. Lab-based FRQs can show buret readings (or describe them) and expect you to subtract initial from final volume, convert to moles using the titrant's molarity, and finish the stoichiometry, like the 2019 FRQ where oxalic acid was titrated with KMnO₄.

## Related Study Guides

- [4.6 Introduction to Titration](/ap-chem/unit-4/intro-titrations/study-guide/8XHQYjYki6GqAcrp18I2)

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