2A(HCO3)n + nH2SO4 -> A2(SO4)n+ 2nCO2+ 2nH2O
nA(HCO3)n = $\frac{9,875}{A+61n}$ mol
=> nA2(SO4)n= $\frac{4,9375}{A+61n}$
=> M A2(SO4)n= $\frac{8,25(A+61n)}{4,9375}= \frac{8,25A+ 503,25n}{4,9375}$
<=> $4,9375(2A+96n)= 8,25A+ 503,25n$
<=> $1,625A= 29,25n$
Ko có giá trị n TM