Is the quality of hydrogen and oxygen produced by electrolysis of water the same as that of the original water

Is the quality of hydrogen and oxygen produced by electrolysis of water the same as that of the original water

Because according to the law of conservation of mass, the mass of water involved in the reaction is equal to the mass of hydrogen and oxygen produced.

How much hydrogen is electrolyzed by 4.5W electric energy? How much hydrogen can be produced by the latest methods? Electrolytic water According to the article of China Hydrogen Energy Network, the electrolytic water of 4.5KW/h is about 1m3, but I have studied the relevant technical aspects and equipment pictures, and found that there are many problems. It seems that there has not been much progress since the experts abandoned this method more than 10 years ago. The foreign articles of China Hydrogen Energy Network have reached 2.88 times. It seems that the biological decomposition method is used, but how can I achieve the level of at least 3 times of the article without adding auxiliary articles except the solution? I can't understand it. What's going on? Did the scientists mislead us, or did we do the wrong thing?

4.5W is a power concept, not an energy concept.
If it's 4.5 WHr, that's the concept of energy to calculate how much hydrogen.
Calorific value of hydrogen is 14.3×10^4J/g
1W=1J/s
So 4.5 WHr =16200J
The amount of hydrogen produced =16200/143000 is approximately equal to 0.113 g.

4.5W is a power concept, not an energy concept.
If it's 4.5 WHr, that's the energy concept to calculate how much hydrogen.
Calorific value of hydrogen is 14.3×10^4J/g
1W=1J/s
So 4.5 WHr =16200J
The amount of hydrogen produced =16200/143000 is approximately equal to 0.113 g.