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Crucible for Laboratory

A laboratory crucible is a small, cup-shaped container designed to withstand extremely high temperatures. They are primarily used for chemical analysis, melting materials, or heating samples to ash (gravimetric analysis) inside a muffle furnace or over a Bunsen burner.

Essential Safety & Handling Best Practices

• Thermal Shock Prevention: Never place a hot crucible directly onto a cold lab bench. Always transfer it to a wire gauze, heat-resistant mat, or directly into a desiccator using clean crucible tongs to prevent cracking.
• The “Pre-Heating” Rule: For precise gravimetric analysis, a crucible must be pre-heated to the target temperature, cooled in a desiccator, and weighed before adding any sample. This ensures all trace moisture or manufacturing oils are entirely removed.
• Loose Fitting Lids: Crucible lids are designed to fit loosely. This allows gases to escape during decomposition or combustion while preventing airborne dust from contaminating the sample inside.

Types of Laboratory Crucibles and Their Applications

There are various types of crucibles, mainly classified by the material they are made of.

Porcelain crucible:
– Advantages: Affordable, easy to handle, good resistance to reagents.
– Disadvantages: Limited to temperatures up to 1000 °C.
– Uses: Simple calcination, gravimetric analysis.

Quartz crucible:
– Advantages: Withstands up to 1300 °C, high chemical resistance, transparency.
– Disadvantages: Fragile, expensive.
– Uses: Processes requiring visual monitoring.

Platinum crucible:
– Advantages: Highly resistant, inert, ideal for precise analysis.
– Disadvantages: Very expensive, sensitive to some elements.
– Uses: Thermogravimetry, fusion of pure materials.

What to choose

The right crucible depends on the sample, required temperature, and chemical compatibility. For most routine chemistry labs, porcelain or alumina is a practical choice; for extreme heat or special chemistry, zirconia, platinum, or graphite may be better.