Which of the following best describes the proper use of a filter funnel during a filtration process?

• A. The filter paper should be laid flat at the bottom of the funnel to maximize surface area.
• B. The funnel should be held above the receiving vessel without contact to prevent contamination.
• C. The filter paper should be folded and placed snugly inside the funnel, with the funnel stem touching the receiving vessel wall.
• D. The funnel should be filled completely with liquid to speed up filtration.

Answer: (C)

Verified step by step guidance

1. Understand the purpose of a filter funnel in a filtration process: it is used to separate solids from liquids by passing the mixture through filter paper placed inside the funnel.
2. Recognize that the filter paper must be folded properly to fit snugly inside the funnel. This ensures that the paper stays in place and the liquid passes through the paper rather than around it.
3. Note that the funnel stem should be positioned so that it touches the wall of the receiving vessel. This helps the filtered liquid flow smoothly down the side of the container, reducing splashing and preventing contamination.
4. Avoid laying the filter paper flat at the bottom of the funnel because this reduces the surface area available for filtration and slows down the process.
5. Do not fill the funnel completely with liquid, as this can cause overflow or slow filtration. Instead, pour the mixture gradually to maintain a steady flow.