Spiders like any bug are typically hearty animals. Sometimes, squashing a bug under a shoe did not kill with a hefty weight. However, the only way to kill a spider with rubbing alcohol would be to drown the spider in a container of the alcohol. Simply putting rubbing alcohol on the spider would not necessarily kill it.
Using a spray that is designed with the ingredients to instantly disable a spider is what is needed. Spiders should be analyzed first before killing them. If they are poisonous, getting close to them to either squash them or picking them up to put them in a jar is dangerous. A Black Widow or Brown Recluse can move fast. It can jump on your skin if you close enough to it. Then it can sting and poison you.