# Catalyst surface area

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1. Mar 25, 2015

### 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?

2. Mar 25, 2015

### 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?

3. Mar 25, 2015

### 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?

4. Mar 25, 2015

### 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?