Reilly Smith and Patrice Bergeron also had goals for the Bruins. The defending Eastern Conference champions are 3-0-1 since losing five of eight, and trail only Pittsburgh in the conference.
"The more you can spread around the scoring, the tougher you are to defend," Bruins coach Claude Julien said. "It's important to have. We like the fact that we are well-balanced and our scoring is spread around."
Chara became the eighth Bruins player to reach double-digits in goals when he scored in the first period to make it 1-0. He also capped the scoring with another power-play goal.
"I think it's important we have a lot of contributions," Iginla said. "When you get in tight games, we feel we have a lot of guys who can find goals. You want a lot of different guys who can score and a lot of guys are feeling it."
Claude Giroux scored a power-play goal for the slumping Flyers, who've lost four in a row. They're 2-5-2 in their last nine games, tumbling from second place in the division to eighth in the East. It's their worst stretch since a 1-7 start that saw coach Peter Laviolette fired three games into the season.
"We need to be a consistent team and that's what we strive to be," coach Craig Berube said. "If you want to be a good team, a playoff team, a team that does something in the playoffs, you have to be consistent. You lose a few games and you're fragile. That's what I see. But we can correct that and go in the right direction. We're a good team. It's a confidence thing for us."
Steve Mason allowed four goals on 19 shots and was yanked for the second time in three starts since signing a contract extension last Saturday.
The Bruins took a 1-0 lead on Chara's first power-play goal in the first period. After Sean Couturier failed on a clearing attempt, David Krejci swung the puck around down low. Iginla passed it to Chara, who flipped a shot from a side angle that bounced off defenseman Braydon Coburn's skate and went in.
Iginla fired a slap shot from the right circle past Mason to make it 2-0 just 17 seconds before the first intermission.
A turnover by defenseman Nicklas Grossmann led to Boston's third goal. Smith stepped around Grossmann and swiped at the puck, which hit the post, hit Mason and went in.
"Teams can't just rely on shutting down one line when you have a lot of guys scoring," Smith said. "It stifles the defense and changes the game."
Rask kept it 3-0 with his toughest save, a sliding glove stab going right to left to rob Jakub Voracek on a one-timer.
Bergeron made it 4-0 minutes later, sending Mason to the bench.
Giroux and Iginla traded power-play goals in the third.
"We have to get better," Giroux said. "We're going away from how we want to be as a team and how we were winning games."
Rask earned his career-high 23rd win. ... Iginla's first goal was his first since Jan. 2, snapping an eight-game drought. ... Flyers D Andrej Meszaros was a healthy scratch despite his recent offensive production. RW Steve Downie also was benched. ... The Bruins are 43-35-12 in Philadelphia. They're the only team with a winning record on the road vs. the Flyers.
Copyright by STATS LLC and The Associated Press
PHILADELPHIA, PA - JANUARY 25: Scott Hartnell #19 of the Philadelphia Flyers leaves the ice surface after warmups...