BURETTE STRAIGHT GLASS STOPCOCK

Description

A Straight Glass Stopcock Burette is a precision volumetric instrument used in analytical chemistry for the accurate dispensing of liquids, most commonly in titration procedures. This model features a classic ground-glass stopcock, which provides a traditional and highly durable control mechanism for drop-by-drop delivery.

Key Product Features

• Precision Borosilicate 3.3 Glass: Manufactured from low-expansion glass that is highly resistant to chemical corrosion from both acids and alkalis, ensuring the internal volume remains calibrated even after repeated cleanings.

• Ground-Glass Straight Stopcock: * Features a precision-ground glass plug that fits perfectly into the barrel.

  • Offers a classic “feel” and high durability.

  • Requires a thin layer of vacuum grease or stopcock lubricant to ensure a leak-proof seal and smooth rotation.

• High-Contrast Graduations: Permanent white or blue enamel markings are fired into the glass for maximum visibility against clear or colored liquids.

• Accurate Calibration: Typically calibrated “To Deliver” (TD/Ex) at 20°C, ensuring that the volume dispensed matches the scale reading.

• Reinforced Tips: The delivery tip is precision-pulled and reinforced to resist chipping and ensure a consistent, reproducible drop size.

Technical Specifications

Primary Applications

• Acid-Base Titrations: The most common use, allowing for the precise measurement of a titrant required to reach a pH endpoint.

• Redox Titrations: Used in the determination of concentration for oxidizing or reducing agents.

• Standard Solution Preparation: Ideal for dispensing specific, high-accuracy volumes of reagents into flasks.

• Volumetric Analysis: Essential for any quantitative chemical analysis where the volume of liquid used must be known to a high degree of precision.

Maintenance & Best Practices

• Lubrication: Since the stopcock is glass-on-glass, it must be lubricated with a small amount of silicone-based stopcock grease. Avoid over-greasing, as this can clog the delivery tip.

• Cleaning: Always clean the burette immediately after use, especially when using alkaline solutions (like NaOH), which can cause the glass stopcock to “freeze” or seize if left for long periods.

• Reading the Meniscus: For clear liquids, read the volume at the lowest point of the curve (the bottom of the meniscus) at eye level to avoid parallax errors.

• Storage: Store the burette vertically in a burette stand or rack. It is recommended to loosen the stopcock slightly during long-term storage to prevent sticking.

Why Choose a Glass Stopcock?

While PTFE (Teflon) stopcocks are popular because they do not require grease, glass stopcocks remain a staple in many professional labs due to their superior resistance to organic solvents and their long-term mechanical stability. When properly maintained, a glass stopcock provides the most reliable and consistent flow control for high-precision analytical work.