Making hydrogen by electrolysis occurs due to the following balanced reaction: lt;/div> 2H2O ---> 2H2 + O2 Therefore there is a 1-to-1 ratio (really 2-to-2, but that's the same) of moles of water to moles of hydrogen gas in the balanced reaction. Therefore the number of moles of hydrogen made is equal to the number of moles of water electrolyzed. lt;/div> We must do the calculation using moles, not grams or kilograms. The molecular weight of H2O is 2*1 + 16 = 18 grams per mole. To find the number of moles of H2O in 2.1 kilogram: lt;/div> 2100 grams ÷ 18 grams/mole = 117 moles of H2O Because of the 1-to-1 stoichiometry of the balanced reaction, it requires 117 moles of hydrogen. The molecular weight of hydrogen is 2 grams/mole. Therefore 117 moles of hydrogen will weigh: lt;/div> 2 grams/mole x 117 moles = 234 grams = 0.234 kilograms
how much hydrogen in grams can be obtained from 2.1 kg of water?