# How do you calculate filtration rate?

Aim: To study the effect of surface area on the rate of filtration.

Requirements:

Chemicals: Calcium carbonate, Water.

Apparatus/Instruments: Beakers, Buchner funnel Of Various sizes, Glass rod, Measuring Cylinder, Stopwatch.

## Principle of Rate of Filtration

• In the process of filtration, the liquid passes through the filter medium, which offers resistance to its passage. The pressure differential across the filter is the driving force for the operation. The rate of filtration is given by:
• Rate of filtration = driving force /resistance
• The resistance for filtration is offered by filter medium and filter cake. The resistance of the filter cake is nothing but the specific resistance of the cake i.e. resistance per unit cake thickness multiplied by the thickness of the cake. The resistance is also proportional to the viscosity of the fluid.
• The other factor affecting the rate of filtration is said to be surface area, pressure drop, viscosity, etc.
• The total volume of filtrate flowing from the filter will be proportional to the area of the filter. The rate of filtration increased by increasing the surface area of the filter medium.

Procedure:

(Effect of surface area on the rate of filtration)

• Buchner funnels with filter paper are arranged properly.
• Three different sizes of Buchner funnel are used in this study.
• The area of each funnel is calculated.
• 2 g of calcium carbonate is weighed and dissolved in 100 ml of water, the prepared slurry is passed through a filtration assembly (small size funnel)
• The time required to collect 50ml of filtrate is recorded.
• The rate of filtration is calculated.
• The same process is repeated for different sizes of the filter assembly and the rate of filtration is calculated for each size.

Formula:

Observations And Calculations:

Results:

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