Burning a magnesium ribbon in the air is an addition reaction while heating potassium manganate 7 is a decomposition reaction.
<h3>Addition and decomposition reactions</h3>Magnesium burns in air to produce magnesium oxide as follows:
Potassium manganate 7 burns to produce multiple products as follows:
Thus, the MgO will be heavier than Mg. On the other hand, will be less heavy than
.
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Answer: The standard free energy change for a reaction in an electrolytic cell is always positive.
Explanation:
Electrolytic cells use electric currents to drive a non-spontaneous reaction forward.
Relation of standard free energy change and emf of cell
where,
= standard free energy change
n= no of electrons gained or lost
F= faraday's constant
= standard emf
= standard emf = -ve , for non spontaneous reaction
Thus
Thus standard free energy change for a reaction in an electrolytic cell is always positive.