Question Video: Identifying the Balanced Symbolic Equation for the Reaction of Iron Metal with Concentrated Sulfuric Acid Chemistry • Third Year of Secondary School

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Which of the following is the correct balanced symbolic equation showing the reaction of iron with hot concentrated sulfuric acid? [A] 3Fe (s) + 8H₂SO₄ (l) ⟶ FeSO₄ (aq) + Fe₂(SO₄)₃ (aq) + 4SO₂ (g) + 8H₂O (g) [B] Fe (s) + H₂SO₄ (l) ⟶ FeSO₄ (aq) + H₂ (g) [C] 2Fe (s) + 5H₂SO₄ (l) ⟶ FeSO₄ (aq) + Fe₂(SO₄)₃ (aq) + 4SO₂ (g) + 8H₂O (g) [D] 4Fe (s) + 8H₂SO₄ (l) ⟶ Fe₂SO₄ (aq) + Fe₂(SO₄)₃ (aq) + 4SO₂ (g) + 8H₂O (g) [E] 4Fe (s) + 9H₂SO₄ (l) ⟶ Fe₂SO₄ (aq) + Fe₃(SO₄)₄ (aq) + 4SO₂ (g) + 8H₂O (g)

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Video Transcript

Which of the following is the correct balanced symbolic equation showing the reaction of iron with hot concentrated sulfuric acid? (A) Three Fe solid plus eight H2SO4 liquid reacts to produce FeSO4 aqueous plus Fe2(SO4)3 aqueous plus four SO2 gas plus eight H2O gas. (B) Fe solid plus H2SO4 liquid reacts to produce FeSO4 aqueous plus H2 gas. (C) Two Fe solid plus five H2SO4 liquid reacts to produce FeSO4 aqueous plus Fe2(SO4)3 aqueous plus four SO2 gas plus eight H2O gas. (D) Four Fe solid plus eight H2SO4 liquid reacts to produce Fe2SO4 aqueous plus Fe2(SO4)3 aqueous plus four SO2 gas plus eight H2O gas. (E) Four Fe solid plus nine H2SO4 liquid reacts to produce Fe2SO4 aqueous plus Fe3(SO4)4 aqueous plus four SO2 gas plus eight H2O gas.

In this question, we want to know which chemical equation best represents the reaction between a mixture of iron and hot concentrated sulfuric acid. The products formed from the mixture of the iron and acid includes ferrous sulfate, ferric sulfate, sulfur dioxide gas, and water vapor.

The term ferric relates to iron in a plus-three oxidation state, whereas the term ferrous relates to an iron compound where iron has a plus-two oxidation state.

From this information, we can rule out answer choice (B) as hydrogen is a product, rather than ferric sulfate, sulfur dioxide, and water. We can also rule out answer choices (D) and (E) as iron in Fe2SO4 would have a one-plus charge not two plus as is required for ferrous sulfate.

We can eliminate the final answer by checking to see which answer choice has an unbalanced equation. Answer choice (A) has three equivalents of iron on each side of the equation therefore is balanced, whereas answer choice (C) has three equivalents of iron on the products side but two on the reactants. Therefore, answer choice (A) is correct.

The correct balanced symbolic equation showing the reaction of iron with hot concentrated sulfuric acid is (A). Three Fe solid plus eight H2SO4 liquid reacts to produce FeSO4 aqueous plus Fe2(SO4)3 aqueous plus four SO2 gas plus eight H2O gas.