[tex]\Large\boxed{\begin{array}{l}\underline{\boldsymbol{equac_{\!\!,}\tilde ao\,balanceada\!:}}\\\sf 2H_2+O_2\longrightarrow 2H_2O\\\sf\underline{c\acute alculo\,da\,massa\,molar\!:}\\\sf m_{H_2O}=2\cdot1+16=2+16=18~g/mol\\\sf 1~mol\,de\,O_2\longrightarrow36\,g\,de\,H_2O\\\sf 18\,mols\,de\,O_2\longrightarrow x\\\sf x=18\cdot36\\\sf x=648~g~de~H_2O\end{array}}[/tex]
