Theo đề bài ta có : \(nH2SO4=\dfrac{100.19,6}{100.98}=0,2\left(mol\right)\)
Ta có PTHH:
\(2NaHSO3+H2SO4->Na2SO4+2H2O+2SO2\uparrow\)
0,4mol.............0,2mol..............0,2mol.........................0,4mol
=> \(C\%Na2SO4=\dfrac{0,2.142}{0,4.104+100-0,4.64}.100\%\approx24,48\%\)