Consider the unbalanced redox reaction: MnO4-(aq) + Zn(s) → Mn2+(aq) + Zn2+(aq). Balance the equation and determine the volume of a 0.500 M KMnO4 solution required to completely react with 2.85 g of Zn.

Verified step by step guidance

Step 1: Identify the oxidation and reduction half-reactions. MnO4^- is reduced to Mn^2+, and Zn is oxidized to Zn^2+.

Step 2: Balance the atoms in each half-reaction. For the reduction half-reaction, balance Mn and then add water molecules to balance oxygen, and H+ ions to balance hydrogen. For the oxidation half-reaction, balance Zn.

Step 3: Balance the charges in each half-reaction by adding electrons. The reduction half-reaction will gain electrons, and the oxidation half-reaction will lose electrons.

Step 4: Equalize the number of electrons transferred in both half-reactions by multiplying the half-reactions by appropriate coefficients, then add the half-reactions together to get the balanced redox equation.

Step 5: Calculate the moles of Zn using its molar mass, then use the stoichiometry of the balanced equation to find the moles of KMnO4 needed. Finally, use the molarity of the KMnO4 solution to find the required volume.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Redox Reactions

Redox reactions involve the transfer of electrons between two species, resulting in oxidation (loss of electrons) and reduction (gain of electrons). In this reaction, MnO4- is reduced to Mn2+, while Zn is oxidized to Zn2+. Understanding the oxidation states of the elements involved is crucial for balancing the reaction.

Balancing Chemical Equations

Balancing chemical equations ensures that the number of atoms for each element is the same on both sides of the equation, adhering to the law of conservation of mass. This involves adjusting coefficients in front of compounds to achieve balance, particularly in redox reactions where electron transfer must also be accounted for.

Molarity and Stoichiometry

Molarity (M) is a measure of concentration defined as moles of solute per liter of solution. Stoichiometry involves using the balanced chemical equation to relate the amounts of reactants and products. In this problem, calculating the moles of Zn from its mass allows for determining the volume of KMnO4 needed based on the stoichiometric ratios from the balanced equation.

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Consider the reaction shown here occurring at 25°C. Cr(s) + Cd²⁺(aq) → Cr²⁺(aq) + Cd(s) Determine E°_cell, K, and ∆G°_rxn for the reaction and complete the table.

[Cd²⁺] [Cr²⁺] Q E_cell 𝚫G_rxn

1.00 1.00

1.00 1.00 × 10^-5

1.00 × 10^-5 1.00

4.18 × 10^-4 1.00

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Determine whether HI can dissolve each metal sample. If it can, write a balanced chemical reaction showing how the metal dissolves in HI and determine the minimum volume of 3.5 M HI required to completely dissolve the sample. a. 2.15 g Al

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