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Rates and rhubarb

Description

In this experiment, rhubarb sticks, which contain oxalic acid, are used to reduce and decolourise potassium manganate(VII) solution. The experiment can be used to show how the rate of reaction is affected by surface area or concentration.

Type of Activity

:
class practical

Audience

:
Teacher

Age Group

:
14 to 18 years

Credits

:
This is an experiment from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry.
rates-and-rhubarb



Apparatus Chemicals

Investigating the effect of surface area:

Eye protection

Each working group will require:

Beakers (100 cm3), 2 or more

Measuring cylinder (50 cm3)

Timer

White tile or piece of paper

Students will need access to:

Knives, 4 to 6 per class (ordinary table knives are probably most appropriate.)

Investigating the effect of concentration:

Additional requirements
Students will need access to:

Filter funnels and filter paper or tea strainers

Each working group will require:

Beaker (250 cm3)

Bunsen burner

Heat resistant mat

Tripod

Gauze

Rhubarb stalks (frozen rhubarb also works if the pieces are long enough) (Note 1)

For the potassium manganate(VII) solution (Note 2):

Potassium manganate(VII) (OXIDISING, HARMFUL, DANGEROUS FOR THE ENVIRONMENT), less than 1g

Dilute sulfuric acid, 1 M, (IRRITANT), volume required depends on the number of student groups (Note 2)

Refer to Health & Safety and Technical notes section below for additional information.

 

 








Page last updated October 2015

In this experiment, rhubarb sticks, which contain oxalic acid, are used to reduce and decolourise potassium manganate(VII) solution. The experiment can be used to show how the rate of reaction is affected by surface area or concentration.

ADDITIONAL INFORMATION

This is a resource from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry. This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. Each activity contains comprehensive information for teachers and technicians, including full technical notes and step-by-step procedures. Practical Chemistry activities accompany Practical Physics and Practical Biology.

The experiment is also part of the Royal Society of Chemistry's Continuing Professional Development course: Chemistry for non-specialists