Description of experiment
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Needed compounds:
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sodium sulfite : Na2SO3
sodium hydroxide : NaOH
metol : (CH3 NH C6H4 OH)2 . H2SO4
Class:
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elem=C,S
photo
redox
Summary:
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Metol is easily oxidized by oxygen from the air, when dissolved in alkaline
media. When sulfite is present, however, oxidation does only occur at a
low rate.
Description:
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Dissolve some NaOH in water and add some metol: The metol dissolves and
while shaking, the liquid turns dark brown/red. This reaction does not
proceed as fast as with hydroquinone, but still an alkaline solution of
metol is oxidized rapidly by oxygen from the air.
Dissolve some NaOH and some Na2SO3 in water and add some metol: The liquid
turns slightly brown, hardly any visible oxidation of metol. The sulfite
protects the metol from oxidation.