Down by three and needing points to stay in the playoff race, the Canucks pulled Demko with 7:20 remaining. He returned less than a minute late as the Sens just missed the empty net.
White added an empty-net goal at 14:33 of the period when Demko went to the bench again, making it 6-2. It was his 10th of the season.
The win moved Ottawa (19-27-4, 42 points) past Vancouver (19-21-3, 41 points) and out of the North Division basement, although the Canucks have seven games in hand due to their lengthy COVID-19 hiatus.
It was the fourth straight meeting between the teams in seven days. Ottawa won the first and third, by 3-0 and 2-1 scores, with Vancouver taking the second, 4-2.
The Sens came into the game having won five of their last seven (5-2-0) — after losing six of their previous seven (1-5-1). They improved to 11-10-4 at home this season.
Vancouver gave Demko his second start since the team returned to action after the COVID outbreak. Braden Holtby had started four of the five previous games.
Mete, acquired April 12 on waivers from Montreal, opened the scoring on Ottawa’s first shot of the game. Taking a pass from Alex Formenton, he split the defense and beat Demko with a low shot at 2:04 for his first point as a Senator.
While the edge in shots was only 11-10 in favor of the Senators after the first period, Hogberg had a far more comfortable 20 minutes than Demko.
The second period was all action with five goals — three for Ottawa and two for Vancouver — in the first seven minutes 23 seconds.
Tierney and Norris scored 32 seconds apart early in the second for Vancouver.
Connor Brown won a battle deep in the Vancouver zone, feeding the puck back to Chabot for a shot from the blue line. Tierney won the battle in front of the net to tuck in the rebounds 38 seconds into the period for a 2-0 lead.
Norris scored seconds later, prompting an irate Vancouver coach Travis Green to call a timeout.
Myers pulled one back, firing a shot through traffic at 5:43 of the second for his fifth of the season. But Chabot answered 53 seconds later, to make it 4-1 with a shot from a tight angle after an Ottawa attack started by a Quinn Hughes turnover.
The goals kept coming with Virtanen, notching his 100th career point, scoring after Hogberg misplayed the puck behind his net. Motte retrieved the puck and sent it back in front for an easy goal that cut the lead to 4-2.
A line change allowed Tkachuk to go in alone and beat Demko glove-side for a 5-2 lead with his 16th of the season.