The leak occurred on a frontage road near Interstate 80 at mile marker 70, officials said.
Ryan Wilden of the North Tooele County Fire District said there was no immediate safety concerns for the public.
"Sulfuric acid can be a nasty chemical, but it's something that can be readily cleaned up.
Union Pacific spokesman Mark Davis said none of the company's employees were injured in the spill. The leak was caused by loose bolts in one of the cars, Davis said. The leak was stopped after about 120 gallons spilled from the car.