What are some long, tedious chemistry lab experiments you had to do for freshman year of college?

I’m writing a story and it centers around a main character who is a freshman in college studying chemistry, and in this one scene he gets frustrated with a particular lab experiment.

I used to take chemistry as a requirement for biology major, and so I tried looking back at the experiments we did but most of them weren’t really as long as I remembered. It wasn’t until organic chemistry that we really did some crazy shit, but I want the main character to mess up something long and arduous for freshman chemistry lab.