Just in case anyone needs a good laugh at my expense, funny thing happened last week in school.

So I’m teaching the types of reactions in chemistry, and describing what happens in a double replacement reaction.  I have a demo for the students, and am pumping them up, getting them excited to see something cool (teaching is all in the setup and presentation)…so they’re ready to go, students are drumming on the desks, eagerly awaiting the demo.

I added a solution of potassium chloride to a solution of lead nitrate, which mix to form lead chloride and potassium nitrate…lead chloride is insoluble while the other three chemicals are water soluble…so you get the effect of pouring two clear liquids together and suddenly a cloudy white solid appears.  Quite dramatic.

Except when I did it, NOTHING HAPPENED.  Ohhhhhh shit (fortunately I didn’t say that out loud)…but I certainly heard it from the students.  Booooooooooooooo.  Why do we have to learn this if it’s not true?

Turns out my solutions were too dilute…I tried it again in the stockroom after school with more concentrated solutions and it worked fine…damn it all. 

Well, there you go.  Lesson learned.