Question

How many grams of water are needed to react with 44.9 grams of li2o?

Answer 1

The  grams  of  water   needed  to  react  with  44.9  grams  of Li2O  is  calculated as  follows 

write  the  equation  for  reaction
Li2O  +H2O  = 2LiOH

find  the  moles  of  Li2O  =  mass/molar   mass
=  44.9/29.9  =  1.5  moles

by  use  of  reacting  ratio  between   Li2O to  H2O  which  is  1:1  the  moles  of  H2O  is  therefore =  1.5  moles

mass  is  therefore  =  moles  x molar  mass
= 1.5 mol  x 18 g/mol  =  27  grams