Passing an electric current through a sample of water (H2O) can cause the water to decompose into hydrogen gas (H2) and oxygen gas (O2) according to the following equation.


2H2O mc026-1.jpg 2H2 + O2


The molar mass of H2O is 18.01 g/mol. The molar mass of O2 is 32.00 g/mol. What mass of H2O, in grams, must react to produce 50.00 g of O2?

Verified Answer :

\(2H_{2} O _{(l)} -------\ \textgreater \ 2H_{2} _{(g)} + O_{2} _{(g)}\)

moles of oxygen in reaction = \(\frac{mass}{molar mass}\)
                                     
                                             =  \(\frac{50.00 g}{32.00 g / mol}\)
                                      
                                             = 1.563 mol

Mole Ratio of oxygen to water in the reaction =  1 : 2
    ∴ for every mole of oxygen there is two moles of water

Thus moles of water in the reaction = (moles of oxygen)    2
                                                         =  1.563 mol  
 2
                                                         =  3.126 mol

Mass of water needed to produce amount of O = mol molar mass
                                         = (3.126 mol)  
 (18.01  g/mol)
                                         =  56.299 g
                                         ≈  56. 3 g

Answer:

d on edge

Explanation: