Answer:
We need 286.1 grams of H2S
Explanation:
Step 1: Data given
Mass of Cr2S3 = 560.0 grams
Molar mass of Cr2s3 = 200.19 g/mol
Step 2: The balanced equation
Cr2O3(s) + 3H2S(g) ⟶Cr2S3(s) + 3H2O(l)
Step 3: Calculate moles of Cr2S3
Moles Cr2S3 = mass Cr2S3 / molar mass Cr2S3
Moles Cr2S3 = 560.0 grams / 200.19 g/mol
Moles Cr2S3 = 2.797 moles
Step 4: Calculate moles H2S
For 1 mol Cr2O3 we need 3 moles H2S to produce 1 mol Cr2S3 and 3 moles H2O
For 2.797 moles Cr2S3 we need 3* 2.797 = 8.391 moles H2S
Step 5: Calculate mass H2S
Mass H2S = moles H2S * molar mass H2S
Mass H2S = 8.391 moles H2S * 34.10 g/mol
Mass H2S = 286.1 grams
We need 286.1 grams of H2S