1) Formation of sulfuric acid (H2SO4) from water (H2O) and sulfuric acid:
2H2O + 2HSO4 -> 2H2SO4

2) Formation of water (H2O) from sulfuric acid (H2SO4) and hydrogen gas (H2):
2H2SO4 + 2H2 -> 2H2O + 2HSO4

3) Overall reaction:
4H2O + 2H2 -> 2H2O + 2HSO4 + 2H2