The Blackhawks took a 1-0 lead at 4:10 of the first period when DeBrincat scored a 5-on-3 power-play goal.
Murphy made it 2-0 at 6:19 with a wrist shot from the point to the blocker side. Toews scored his 33rd goal on a rebound, increasing the lead to 3-0 at 10:59.
"We've had trouble scoring lately so to get those goals was probably a relief for everyone," Blackhawks coach Jeremy Colliton said. "We knew they were a desperate team also, they've been struggling, so you're kind of worried going into a game like this when they're at home and they've had a couple of games to sit on the results, so really good start for us."
San Jose cut it to 3-1 at 11:59 on Lukas Radil's wrist shot from the right face-off circle.
Nyquist's power-play goal on a snap shot at 2:33 of the second period brought San Jose within 3-2.