A white powder is known to be a mixture of MgO and Al2O3.
100 cm3 of 2 M NaOH(aq) is just sufficient to cause the Al2O3 in x grams of the mixture to dissolve.
the reaction occurring is
Al2O3 + 2OH- + 3H2O ..2Al(OH)4-
800 cm3 of 2 M HCl(aq) is just sufficient to cause all
the oxide in x grams of the mixture to dissolve.
AL2O3 + 6H+ ...2Al3+ + 3H2O
MgO + 2H+ ...Mg2+ + H2O
how many moles of each oxide are present in x grams of the mixture?
Answer is : Al2O3 ..0.10 g
MgO ..0.50 g
For moles of Al2O3....According to first equation moles of NaOH = 0.20 ; so moles of AL2O3 will be 0.10
for moles of MgO...There are 1.6 moles of HCl but this is used for BOTH oxides. so will it be
Moles of MgO = [Total moles of HCl] – [Moles of HCl used for Al2O3] /2 .
but did not get the right answer ??