The England Under-21 international, who arrived at Turf Moor from Bolton Wanderers last month, struck for the third time in pre-season as Burnley bounced back from a 2-1 reverse at Preston North End on Tuesday.
Sordell netted twice in an 8-0 hammering of Grossklein in Austria a fortnight ago and was on target again midway through the second half as Sean Dyche's men recorded their third victory from four friendly matches.
Blackpool's squad consisted mostly of trialists as boss Jose Riga's problems continue to mount, with the start of the Football League season just a week away.
Blackpool's first effort of note arrived in the 29th minute when Tony McMahon sent a free-kick over the bar.
Burnley continued to press as half-time approached, with Barnes firing a snap-shot narrowly wide in the 44th minute.
Ross Wallace and Scott Arfield both brought saves from the hosts' trialist goalkeeper in the opening five minutes of the second half as the Premier League side began to assert themselves.
Burnley will now host Celta Vigo on Tuesday and Verona next Saturday, before their return to the top flight begins with a home clash against Chelsea on August 18.
