Hanging heavy object in bedroom
My opinion of the anchors that you posted is pretty low. There are far better anchors available than those. As a matter of fact those anchors are touted to be for "solid material walls, floors and ceilings". I personally do not consider drywall to be a particularly solid material in the same way that wood, brick or concrete would be. 

Your wall is probably made up two layers of 1/2" drywall to be both a fire stop and sound deadening between the neighbors unit and yours.

If I were to be hanging a heavy mirror on 1" thickness surface drywall I would look at toggle type anchors that look like this: