(2012?Huzhou) When using hydrogen peroxide to make oxygen, a student had questions about adding water to the flask beforehand. He put forward a conjecture: Conjecture 1: the addition of water can be

(1) hydrogen peroxide in the case of manganese dioxide as a catalyst can be decomposed to produce water and oxygen, the equation is: 2H2O2

? MnO2?

2H2O+O2↑;

(2) from the data in the table can be seen, other conditions remain unchanged, the higher the solute mass fraction of hydrogen peroxide to generate 500mL of oxygen the shorter the time used, i.e., the faster the reaction rate, but the time used in the reaction is not proportional to the mass fraction of the solute, so this law should be in a certain range; < /p>

(3) from the data in the table can be seen, the smaller the solute mass fraction of hydrogen peroxide solution after the reaction of the solution temperature is lower, that is, the more water is added after the reaction of the solution temperature is lower, so it can be guessed that the addition of water can be cooled down the solution;

The answer is: (1) 2H2O2

?MnO2?

2H2O + O2↑;

(2) Within a certain range, the larger the hydrogen peroxide solute mass fraction the faster the reaction;

(3) Cooling down the solution;