How can we predict the yield of a reaction?
Students use a familiar baking soda/vinegar reaction to see if their theoretical yield and their experimental yield are consistent. Can stoichiometry really tell us what will happen? (When we did this lab, results were excellent!)
Stoichiometry Intro Lab: Student Handout
Stoichiometry Intro Lab: Teacher Notes
Stoichiometry Intro Lab: Student Handout
Stoichiometry Intro Lab: Teacher Notes
What if our reactants are not in mole ratio proportions?
This lab introduces the concept of limiting and excess quantities with a familiar Zinc/HCl reaction. Students measure products and relate them back to the limiting reactant. (Based on Heath Lab 6E)
Note: I've left this lab online, but the way it's written, it has some problems.
This lab data would be reliable if you were trying to look only at the Zn consumed / Zn leftover.
If you are trying to analyze the mass of hydrogen gas formed, the water loss through evaporation will pollute your data.
In the spirit of inquiry, this lab was meant to show students that you can't get more product than your limiting reactant allows... but the data suggests a 200% yield. Yikes! If you use this activity, leave the gases out of it.
Limiting XS Lab: Student Handout
Limiting XS Lab: Teacher Notes
Note: I've left this lab online, but the way it's written, it has some problems.
This lab data would be reliable if you were trying to look only at the Zn consumed / Zn leftover.
If you are trying to analyze the mass of hydrogen gas formed, the water loss through evaporation will pollute your data.
In the spirit of inquiry, this lab was meant to show students that you can't get more product than your limiting reactant allows... but the data suggests a 200% yield. Yikes! If you use this activity, leave the gases out of it.
Limiting XS Lab: Student Handout
Limiting XS Lab: Teacher Notes
Which is the limiting reactant?
A lovely, quick demo that makes students think, and justify their understanding of limiting & excess from both observations and theory. By this point in the year, I'm usually trying hard to be efficient with my time. This demo is efficient!
Limiting XS balloon demo: Student Handout
Limiting XS balloon demo: Teacher Notes
Limiting XS balloon demo: Student Handout
Limiting XS balloon demo: Teacher Notes
What's the concentration of this base?
As a prelude to proper titration technique, this activity explores the concept of reacting acid with base until a neutral solution is obtained. Students figure out how the stoichiometry of a titration is connected.
After this lab, I would do a proper titration as a fully structured experiment so that students can learn how to use the equipment.
Pre-Titration Challenge: Student Handout
After this lab, I would do a proper titration as a fully structured experiment so that students can learn how to use the equipment.
Pre-Titration Challenge: Student Handout
How strong is that NaOH? A summative stoichiometry lab
This reaction involves formation of a magnesium hydroxide precipitate, and asks students to determine the concentration of base used to produce it.
I gave a final lab exam that looked very similar to this (but with a different reaction).
At the end of my first semester doing inquiry, students were NOT prepared for that much independence.
Next time I plan to do this lab at the end of our stoichiometry unit so that I can support students through it. Then, when the final lab rolls around, they'll have a better background to deal with it.
Summative Stoichiometry Lab: Student Handout
Summative Stoichiometry Lab: Teacher Notes
I gave a final lab exam that looked very similar to this (but with a different reaction).
At the end of my first semester doing inquiry, students were NOT prepared for that much independence.
Next time I plan to do this lab at the end of our stoichiometry unit so that I can support students through it. Then, when the final lab rolls around, they'll have a better background to deal with it.
Summative Stoichiometry Lab: Student Handout
Summative Stoichiometry Lab: Teacher Notes