What's a misconception you've had in Chemistry?

I thought it was hard, but it wasn’t.

that you can take it in university without any other subjects… I found out that you need biology, math, physics and two high school arts classes (English, social studies ect…) to take any of the fun courses

Everything I ever learnt in the school curriculum.

I didn’t have any misconception. I knew right from the get go that trying to do mathematical equations with a slide rule just wasn’t going to happen for me. And I found out later that the reason that the chemistry teacher wouldn’t press my parents to supply me with a calculator like half the other students was because his own 9 and 10yro were freakin geniuses and were already doing HS chemistry with their GD slide rulers. aaaarrrrrgh!

I never realized that chemical bases can be just as corrosive as acids. I learned that the hard way when I was working on a chemical pump and got some of the caustic (I think it was sodium hydroxide) on my arm.