C=md/ms*100 => md=C*ms/100=20*100/100=20g NaOH
MNaOH=ANa+AO+AH=23+16+1=40g/mol
MHCl=AH+ACl=1+35,5=36,5g/mol
MNaCl=ANa+ACl=23+35,5=58,5g/mol
NaOH + HCl => NaCl + H2O
40g NaOH................36,5g HCl
20g NaOH................x=18,25g HCl
C=md/ms*100 => ms=md*100/C=18,25*100/20=91,25g sol. HCl
40g NaOH.....................58,5g NaCl
20g NaOH.....................x=29,25g NaCl
n=m/M=29,25/58,5=0,5 moli NaCl (sare de bucatarie)