how can I kill a program at a specified time?

hello, I want to be able to kill a program at a specified time. I don't want to set up the cron tab, I just want a simple command to type into the terminal. Example: I want to kill Firefox, say, in 2 hours and 10 minutes, how would I do that? I think it involves the "at" and "kill" command, but don't know how to word it. Thanks for any info.