Increase Catalyst Surface Area & Reaction Rate: Experiment

[tvbuddy01]

Hi there,

I am doing an experiment in increasing the mass of MnO2 when it is added to H2O2 decomposition, and I'm measuring the rate of temperature change. I chose increments of 0.050, 0.100, 0.150, 0.200, and 0.250 g to put into H2O2 when it is decomposed, i.e. the MnO2 is a catalyst. I noticed a generally increasing trend.

I was wondering... I know that increasing the mass of the catalyst is just increasing the total surface area it has, but how exactly is surface area related to the rate of reaction?

 

[epenguin]

Ideally rate should be simply proportional to surface area which then should be proportional to the mass added if it is a uniform dispersed solution of particles. I.e. Particles not clumping together or sticking to the glass. Those assumptions may not be the case in your experiment. Also are you really measuring a rate? Does it seem to be constant with time in your experiment?

 

[tvbuddy01]

I do have an increasing trend. i.e. the more MnO2 I added in, the higher the rate.

Why exactly is the rate proportional to surface area of the catalyst?

 

[epenguin]

Things like it are actually called 'surface catalysts' (and include I'd say, the majority of large scale industrial reactions).
In a very generic way guess how they work. Isn't proportionality to area what you'd expect?