In a laboratory 178.8 g of water is separated into hydrogen gas and oxygen gas. the hydrogen gas has a mass of 20.0 g what is the mass of the oxygen gas produced?

Below is the solution:
n equation showing conservation of mass of reactants and products: 
2H2O --> 2H2 & O2 

what is the mass of the oxygen gas produced, from 178.8 g H2O , (using molar masses: 
178.8 g H2O @ (1mol O2)(@ 32.00 g/mol) / (2molH2O)(18.02g/mol) = 
your answer (4 sigfigs): 158.8 g O2 

178.8 g H2O ---> 20.0 H2 & 158.8 O2

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