Chromium(III) oxide reacts with hydrogen sulfide (H_2S) gas to form chromium(III) sulfide and water:. Cr_2 O_3 (s) + H_2S (g) ? Cr_2S_3 (s) + 3H_2O (l)
To produce 346 g of Cr_2S_3,
(a) how many moles of Cr_2 O_3 are required?
mol
(b) how many grams of Cr_2 O_3 are required?
g

a. 1.728 moles.

b. 262.7g of Cr₂O₃ are required

Explanation:

Based on the reaction:

Cr₂O₃(s) + 3H₂S(g) → Cr₂S₃(s) + 3H₂O(l)

The important thing in the reaction is that 1 mole of Cr₂O₃ produce 1 mole of Cr₂S₃

a. To produce 346g of Cr₂S₃ we must know how many moles of Cr₂S₃ must be produced, and, as 1 mole of Cr₂O₃ produce 1 mole of Cr₂S₃ we can know moles of Cr₂O₃ that are required.

Moles of 346g Cr₂S₃ (Molar mass: 200.19g/mol):

346g Cr₂S₃ * (1mol / 200.19g) = 1.728 moles of Cr₂S₃

Based on the reaction, moles of Cr₂O₃ that are required are

b. Again, to conver the 1.728 moles of Cr₂O₃ to grams we must use molar mass of Cr₂O₃ (151.99g/mol):

1.728 moles Cr₂O₃ * (151.99g / mol) =

b.final