Indicate whether the following balanced equations involve oxidation–reduction. If they do, identify the elements that undergo changes in oxidation number. (b) 2 PbO₂(s) → 2 PbO(s) + O₂(g) (c) 2 H₂SO₄(aq) + 2 NaBr(s) → Br₂(l) + SO₂(g) + Na₂SO₄(aq) + 2 H₂O(l)

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780134414232

검증된 단계별 안내

Step 1: Understand the concept of oxidation-reduction (redox) reactions. These involve the transfer of electrons between species, leading to changes in oxidation numbers of elements involved.

Step 2: For equation (b) 2 PbO_2(s) → 2 PbO(s) + O_2(g), determine the oxidation states of lead (Pb) and oxygen (O) in both reactants and products. In PbO_2, Pb is typically +4 and O is -2. In PbO, Pb is +2 and O is -2.

Step 3: Analyze the changes in oxidation states for equation (b). Lead (Pb) changes from +4 in PbO_2 to +2 in PbO, indicating a reduction. Oxygen (O) changes from -2 in PbO_2 to 0 in O_2, indicating an oxidation.

Step 4: For equation (c) 2 H_2SO_4(aq) + 2 NaBr(s) → Br_2(l) + SO_2(g) + Na_2SO_4(aq) + 2 H_2O(l), determine the oxidation states of sulfur (S), bromine (Br), and other elements in both reactants and products. In H_2SO_4, S is +6, and in NaBr, Br is -1.

Step 5: Analyze the changes in oxidation states for equation (c). Bromine (Br) changes from -1 in NaBr to 0 in Br_2, indicating an oxidation. Sulfur (S) changes from +6 in H_2SO_4 to +4 in SO_2, indicating a reduction.

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Oxidation-Reduction Reactions

Oxidation-reduction (redox) reactions involve the transfer of electrons between substances, leading to changes in oxidation states. In these reactions, oxidation refers to the loss of electrons, while reduction refers to the gain of electrons. Identifying whether a reaction is a redox process requires analyzing the oxidation states of the elements involved before and after the reaction.

Oxidation States

Oxidation states (or oxidation numbers) are assigned to atoms in a compound to indicate their degree of oxidation or reduction. These states help track the movement of electrons during chemical reactions. Common rules for determining oxidation states include that the oxidation state of an element in its elemental form is zero, and for compounds, the sum of oxidation states must equal the overall charge of the molecule.

Balancing Chemical Equations

Balancing chemical equations ensures that the number of atoms for each element is the same on both sides of the equation, reflecting the law of conservation of mass. In redox reactions, balancing also involves ensuring that the total charge is the same on both sides. This process often requires adjusting coefficients and can involve half-reactions to separately account for oxidation and reduction processes.

Indicate whether the following balanced equations involve oxidation–reduction. If they do, identify the elements that undergo changes in oxidation number. (b) 2 PbO2(s) → 2 PbO(s) + O2(g) (c) 2 H2SO4(aq) + 2 NaBr(s) → Br2(l) + SO2(g) + Na2SO4(aq) + 2 H2O(l)

주요 개념

Oxidation-Reduction Reactions

Oxidation States

Balancing Chemical Equations

Indicate whether the following balanced equations involve oxidation–reduction. If they do, identify the elements that undergo changes in oxidation number. (b) 2 PbO₂(s) → 2 PbO(s) + O₂(g) (c) 2 H₂SO₄(aq) + 2 NaBr(s) → Br₂(l) + SO₂(g) + Na₂SO₄(aq) + 2 H₂O(l)