This week I started the stoichiometry unit with my chemistry classes. A great intro to stoichioimetry lab to do with students uses the single replacement reaction of copper (II) sulfate and iron. I love this lab because I can use it with both my honors and college-prep classes.
Students will dissolve enough copper (II) sulfate into water so that it is in excess and will heat to dissolve. Then the students slowly (if not, I feel sorry for your hot plate!) add the iron and there you have it, COPPER. Many times they say "that looks like rust." So you often will have to gently correct them.
This year wasn't any different than any other year I have done this lab, except I used a new trick to help get rid of that nasty film around the bottom of the beaker that the copper leaves behind. Regular old soap and water isn't cutting it here. Instead I used 6M hydrochloric acid and it worked like a charm! If you don't use this trick, I hate to break it to you, your arm may fall off from exhaustion AND you will be really upset because after all that, the brown stain just simply is not going away any time soon. Here's a snap shot of my beakers after I did the lab:
Yikes. Thank goodness for the HCl. Posted below you can find this lab and many others at my Teachers Pay Teachers store. For this lab in particular I included a post-lab quiz for easy assessment. Sometimes you need a break from grading those lab reports!
Karen (MsRazz ChemClass)