nAl = 2.97/27 = 0.11 (mol)
nS = 0.1275 (mol)
2Al + 3S -to-> Al2S3
0.085_0.1275__0.0425
nAl dư = 0.025 mol
2Al + 6HCl => 2AlCl3 + 3H2
0.025_______________0.0375
Al2S3 + 6HCl => 2AlCl3 + 3H2S
0.0425_________________0.1275
%VH2 = 0.0375/(0.0375 + 0.1275) * 100% - 22.43%
%VH2S = 77.27%