Type of spider?
Spiders can be alarming when they are large, and they startle us. However, spiders eat other small bugs, and are usually beneficial and rarely bite. It is a misnomer that spider bites are common, as most spiders are very shy and avoid interaction with people. The fact that this one was in your bathtub indicates it was in there accidentally and could not get out. A better choice may have been to crush it with the bottom of a shoe, Chemicals are usually not effective against spiders, as they are not insects.
I cannot identify it from the picture, although it is definitely not a black widow or venomous spider, but merely a house spider. Although scary, they are harmless.
Thank you for contacting Cooperative Extension,