Qualitative Filter Paper (100 circles per pack) is a fundamental consumable in school science labs, primarily used for general-purpose filtration where the solid residue does not need to be weighed. Unlike quantitative (ashless) paper, it is designed for identifying materials rather than precise mass measurement.
Common Sizes for School Use
These circles are available in various diameters to fit standard laboratory funnels:
- Small: 70mm, 90mm
- Medium (Standard): 110mm, 125mm, 150mm
- Large: 185mm, 240mm
- Recommendation: For the best fit, choose a circle diameter that is approximately 1.5 to 1.8 times the diameter of your funnel rim.
Classroom Applications
- General Filtration: Separating sand from water or clearing cloudy solutions.
- Precipitate Separation: Collecting solids formed during chemical reactions, such as calcium carbonate.
- Paper Chromatography: Used as a stationary phase to separate ink pigments or leaf extracts.
- Soil Analysis: Filtering soil extracts to test for pH or nutrient content.