\(NH_4HSO_4+Ba\left(OH\right)_2\rightarrow BaSO_4+NH_3+2H_2O\)
\(x------x-----x----x---2x\)
\(n_{NH_4HSO_4}=\frac{11,5}{115}=0,1\left(mol\right);n_{Ba\left(OH\right)_2}=\frac{13,68}{171}=0,08\left(mol\right)\)
\(\Rightarrow x=n_{Ba\left(OH\right)_2}=0,08\left(mol\right)\)
\(\Rightarrow m_{BaSO_4}=18,64\left(g\right);V_{NH_3}=22,4.0,08=1,792\left(l\right)\)