Description of experiment
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Needed compounds:
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potassium dichromate : K2Cr2O7
formic acid : HCOOH
Class:
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elem=C,Cr
redox
Summary:
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Potassium dichromate reacts with formic acid, producing a gas (CO2) and
itself being reduced to trivalent chrome.
Description:
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Add a spatula full of potassium dichromate to formic acid (appr. 85% by
weight): The solid partly dissolves and the liquid becomes yellow/orange,
but quickly it becomes darker and evolution of a gas can be observed. At
a certain moment, the reaction proceeds smoothly and quickly without being
violent. The liquid becomes luke-warm. After the reaction, the liquid is
clear and dark bluish/grey/violet (color is difficult to describe and
depending on the viewing illumimant).