Filter funnels, paper and pouring rods: jobs and limits
Explain funnel, paper and pouring-rod roles, residue and filtrate, and why clear liquid is not proof of purity.
A funnel supports the paper and directs the liquid. The paper retains suitable insoluble particles. A pouring rod helps direct a stream into the supported assembly. None of these parts identifies the mixture or makes its filtrate safe to drink.
This guide covers the supplied room-temperature sand and salt-solution example. Use the gravity-filtration guide to understand assembly, transfer and recovery, then follow the trainer's assigned method. Hot or vacuum filtration needs a different setup and assessment.
Support the paper and keep the rim visible
The paper must separate the incoming mixture from the receiver. Liquid that travels over its rim or around a tear has bypassed that barrier.
- Filter paper. Holds back insoluble particles that are large enough for this paper to retain. Dissolved substances can pass through.
- Funnel. Supports the paper and directs the liquid. Check that the funnel and its support suit the mixture and method.
Stock photograph for illustration by Jahra Tasfia Reza on