Chromium is dissolved in sulfuric acid according to the following equation: Cr + H2SO4 ⇒ Cr2 (SO4) 3 + H2 a) How many grams of Cr2 (SO4) 3 can be obtained by reacting 165 g of 85.67% H2SO4 of purity?

b) If 485.9 g of Cr2 (SO4) 3 are obtained, what is the yield of the reaction?

Explanation:

We will need a balanced chemical equation with masses and molar masses, so, let's gather all the information in one place.

Mᵣ:                      98.08           392.18

             2Cr + 3H₂SO₄ ⟶ Cr₂(SO₄)₃ + 3H₂

To solve the stoichiometry problem, you must

Use the molar mass of H₂SO₄ to convert  the mass of H₂SO₄ to moles of H₂SO₄ Use the molar ratio to convert moles of H₂SO₄ to moles of Cr₂(SO₄)₃ Use the molar mass of Cr₂(SO₄)₃ to convert moles of Cr₂(SO₄)₃ to mass of Cr₂(SO₄)₃

a) Mass of Cr₂(SO₄)₃

(i) Mass of pure H₂SO₄

(ii) Moles of H₂SO₄

(iii) Moles of Cr₂(SO₄)₃

The molar ratio is 1 mol Cr₂(SO₄)₃:3 mol H₂SO₄

(iv) Mass of Cr₂(SO₄)₃

b) Percentage yield

It is impossible to get a yield of 485.9 g. I will assume you meant 185.9 g.

Exothermic,  physical change after it is already baked

C. chemical changeshope i : )