Ch.19 - Electrochemistry

Problem 109a

Chapter 19, Problem 109a

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

Verified step by step guidance

Identify the reaction: Aluminum (Al) reacts with hydroiodic acid (HI) to form aluminum iodide (AlI3) and hydrogen gas (H2). The balanced chemical equation is: 2 Al + 6 HI -> 2 AlI3 + 3 H2.

Calculate the moles of aluminum: Use the molar mass of aluminum (approximately 26.98 g/mol) to convert the mass of aluminum (2.15 g) to moles.

Determine the stoichiometry: From the balanced equation, 2 moles of Al react with 6 moles of HI. Use this ratio to find the moles of HI needed.

Calculate the volume of HI solution: Use the molarity of the HI solution (3.5 M) to convert the moles of HI required to volume in liters.

Convert the volume to milliliters: Since the problem may require the volume in milliliters, convert the volume from liters to milliliters by multiplying by 1000.

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Key Concepts

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

Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) between reactants. In this context, hydroiodic acid (HI) acts as a strong acid that can donate protons to metals, facilitating their dissolution. Understanding how acids interact with metals is crucial for predicting whether a metal will dissolve in HI and for writing the corresponding balanced chemical equations.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the conservation of mass. It allows us to determine the amounts of substances involved in a reaction. In this case, stoichiometry will help calculate the minimum volume of 3.5 M HI needed to dissolve 2.15 g of aluminum by using the molar mass of aluminum and the balanced chemical equation.

Metal Reactivity

Metal reactivity refers to the tendency of a metal to undergo chemical reactions, particularly with acids. Metals like aluminum can react with strong acids such as HI, leading to the formation of metal ions and hydrogen gas. Knowing the reactivity series helps predict whether a specific metal will dissolve in a given acid, which is essential for answering the question.

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Related Practice

Textbook Question

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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Open Question

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.

Textbook Question

Consider the unbalanced redox reaction: Cr₂O₇^2-(aq) + Cu(s) → Cr³⁺(aq) + Cu²⁺(aq) Balance the equation and determine the volume of a 0.850 M K₂Cr₂O₇ solution required to completely react with 5.25 g of Cu.

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. b. 4.85 g Cu

Determine if HNO₃ can dissolve each metal sample. If it can, write a balanced chemical reaction showing how the metal dissolves in HNO3 and determine the minimum volume of 6.0 M HNO3 required to completely dissolve the sample. a. 5.90 g Au b. 2.55 g Cu c. 4.83 g Sn

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