TMM

You have to add some H+'s to make it all work. 5CaC2O4 + 2MnO4^- +6H^+ ==> 10CO2 + 8H2O + 2Mn^2+ I've left out the states since they make it more confusing when typing it out. I hope this helps!

I've graphed those values in Excel and then compared it to your image. The graphs are the same, and my R2 value is closer to your friend's value. Basically, your trendlines are different; the scatterplots are same. You must have set the intercept to 0.0 a...