Eternal Hell and Merciful God?

Suffering in an eternal Hell creates a contradiction between this divine justice, since eternity can not be equal to an evil committed in during a limited life span of a human. However, eternal punishment in life time of a non eternal Hell avoids such a contradiction. After receiving an equivalent punishment the chief evil-doers like those referred in verse 4:48, will be eliminated from existence. They will end up in Hell and Hell will end up in nothingness.