Ascientist measures the rate of a reaction between two liquids. then he performs the reaction again, adding solid manganese. the reaction takes place more quickly the second time. the mass of the manganese decreased by 0.45 grams during the reaction. he claims that the manganese acted as a catalyst because it sped up the reaction. explain what is wrong with the scientists' reasoning.

The manganese is not functioning as a catalyst.

Explanation:

A substance that can be supplemented to a reaction to enhance the rate of a reaction without getting used up in the process is known as a catalyst. The catalysts generally accelerate the reaction by changing the mechanism of the reaction or by minimizing the activation energy.  

Thus, if the manganese is used as a catalyst then its mass would not have been decreased, and it would just continue to change the reaction unless and until it gets consumed. Therefore, manganese is not functioning as a catalyst.