Massa Molar Al2S3 = 2*27 + 3*32 = 150g/mol
1 mol --------- 150g
x mols --------200g
150x = 200
x = 200/150 = 20/15 mols
Proporção Al ----- Al2S3 = 2 para 1
Al2S3 = 20/15 mols
Al = 2 * 20/15 = 40/15 mols
Massa Molar Al = 27g/mol
27g -------- 1 mol
x g --------40/15 mols
x = 27 * 40 / 15
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x = 72 gramas de Alumínio
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