It does matter if they play at home or not. If Chelsea were to play this game away against Arsenal, I think it would almost be certain that Arsenal would win the game, but since this isn't a home game for Arsenal, I think that it is possible for Chelsea to play a better game than they would otherwise. Whether that is enough for a win for them, I don't know. But playing in front of their own fans is at least supposed to be a different atmosphere for them that should help them to put more effort into that game.
Play home or away its not really difference atmosphere for Chelsea because last winning match from away when defeating Burnley, but Arsenal opponent is difference than Burnley with consistency performance and they have more confidence after last match before international break out success beaten defending champion of Premier League teams Manchester City.
Otherwise, Arsenal have more motivate take first position standings from other London team Tottenham Hotspur, have the same points with lack goals productive I think three points against Chelsea will move to the first position place for awhile due Tottenham Hotspur vs Fulham will play on Tuesday.
Chelsea did show some improvement in their last 2 matches against Fulham and Burnley, they were able to win the matches away from homed, even though Chelsea will play as host in the next match against Arsenal don't forget that Arsenal is a tough opponent for Chelsea at the moments.
Arsenal has not received defeat in 8 matches in the premier league.
Arsenal is a stronger club at the moment, play at home or away is not a big problems for Arsenal because he is able to perform impressively in every condition, especially since Arsenal just beat Manchester City and the matches against Chelsea is certainly not difficult for Arsenal.