Europa League: Arsenal need to remain strong’ -Emery
Chelsea took control in the 49th minute when Olivier Giroud met Emerson's pass with a diving header into the net - it was the French striker's 11th goal in 14 games in the Europa League.
Pedro doubled the lead when he found space in the penalty area in the 60th to stroke in a cut-back pass from Hazard.
It was soon 3-0 when Hazard converted a penalty after Ainsley Maitland-Niles shoved Giroud in the box.
Two minutes after coming off the bench, Alex Iwobi punished Chelsea with a volley from the edge of the box to make it 3-1 in the 69th.
But Arsenal's hopes of a comeback were extinguished three minutes later when Hazard scored his second.