# Experiment to demonstrate Dalton's Law of Multiple Proportions

Is there an experiment that I can do in the lab with middle or high school students to demonstrate Dalton's Law of Multiple proportions ?

For example, the reaction of $$\ce{C}$$ and $$\ce{O2}$$ to give $$\ce{CO}$$ and $$\ce{CO2}$$.

Is there an experiment where I can demonstrate that $$\ce{CO}$$ and $$\ce{CO2}$$ have these proportions ?

Because of toxicity, I'd avoid middle or high school student experimentation with $$\ce{CO}$$.
You might consider $$\ce{H2O}$$ and $$\ce{H2O2}$$, if you stick to 6% (20 vol) or weaker. There is the complication of working with a dilute solution, though, in getting precise measurements on proportions.
Another possibility is demonstrating the various oxides of iron. However, there is another issue: you can produce fairly pure pure red iron(III) oxide, $$\ce{Fe2O3}$$, by the electrolysis of sodium bicarbonate, $$\ce{NaHCO3}$$ with an iron anode, but rather than pure black iron(II) oxide, $$\ce{FeO}$$, thermal decomposition of iron(II) oxalate in an inert atmosphere, makes a mix, wustite (a nonstoichiometric compound) that is primarily $$\ce{FeO}$$.