Real World Application: Drain Cleaners - Should I use them?

Common drain cleaners consist of water, sodium hypochlorite (bleach) and sodium hydroxide (base) and/or potassium hydroxide (base). Bases are caustic (caustic loosely means to gnaw or eat away at) and can cause corrosion in metal pipes. Wouldn’t you know, our house has PVC piping through the fixtures that dump into a 45 year old cast iron pipe. The cast iron pipe is old and currently shows signs of surface rust and corrosion to the point where the pipe appears to be leaking then sealing itself in several spots. Not to mention the interior of the cast iron pipe may not be completely open, thus, not permitting a fast flow in drainage. Good news: a home warranty is being taken advantage of to hopefully replace the cast iron pipe with a PVC pipe.


My First Day Demonstration

I have a first day routine that I am very proud of. I have used it for 25 years and I think I finally have it down pat. I have spoken to students from 20 years ago at reunions and they tell me that they still remember the first day of chemistry so I think it is pretty good.

Lab 20 aka Check the Solution!

Last night I had the opportunity to do another lab that I wrote with my students.  It is so exciting to see something go from words on a screen to a group of students working together in a laboratory.  I learned so much as I walked around the room last night.  Here are a few highlights:

Mass of a Reaction Product

Students combine sodium carbonate and hydrochloric acid generating carbon dioxide gas which is allowed to escape. They measure the actual yield of carbon dioxide produced (missing mass), calculate the theoretical yield using stoichiometry, and then the percent yield. Students understand that 100% yield is the most appropriate answer (based on the Law of Conservation of Mass), so after considering the meaning of significant figures and the uncertainty of their measurements they are asked to decide if they did (or did not) get an answer that might indicate the validity of the Law.

Chemical Riddle #2

A student of mine, Anthony Shepherd, and I worked together to develop a new chemical riddle. Check out the video and see if you can come up with an answer.

Bath Bubblers

In this Activity, students use citric acid and baking soda to make "bath bubblers" similar to those sold in bath and body stores. They investigate the fizzing reaction that occurs when the bubblers are added to both cold and hot water. Bringing this real world product into the classroom adds interest and can lead to creativity, while introducing both acid/base concepts and rates of reaction.