Textbook Question
Calculate ∆G°rxn and K for each reaction.
a. The disproportionation of Mn2+(aq) to Mn(s) and MnO2(s) in acid solution at 25 °C.
b.The disproportionation of MnO2(s) to Mn2+(aq) and MnO4–(aq) in acid solution at 25 °C.
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Ch.19 - Electrochemistry
Chapter 19, Problem 123
The molar mass of a metal (M) is 50.9 g/mol; it forms a chloride of unknown composition. Electrolysis of a sample of the molten chloride with a current of 6.42 A for 23.6 minutes produces 1.20 g of M at the cathode. Determine the empirical formula of the chloride.
Verified step by step guidance1
Calculate the total charge (Q) passed during electrolysis using the formula Q = I \times t, where I is the current in amperes and t is the time in seconds.
Convert the time from minutes to seconds by multiplying the given time in minutes by 60.
Use Faraday's laws of electrolysis to determine the moles of electrons transferred. The formula is moles of electrons = \frac{Q}{F}, where F is Faraday's constant (approximately 96485 C/mol).
Determine the moles of metal (M) deposited using the given mass and molar mass of the metal: moles of M = \frac{1.20 \text{ g}}{50.9 \text{ g/mol}}.
Assume the metal forms a chloride of the form MCl_x. Use the stoichiometry of the reaction and the moles of electrons to find the value of x, which represents the number of chloride ions per metal ion in the empirical formula.
Related Practice
Textbook Question
Calculate ∆Gr°xn and K for each reaction. a. The reaction of Cr2+(aq) with Cr2O7^2-(aq) in acid solution to form Cr3+(aq).
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Textbook Question
Calculate ∆Gr°xn and K for each reaction. b. The reaction of Cr3+(aq) and Cr(s) to form Cr2+(aq). [The electrode potential of Cr2+(aq) to Cr(s) is -0.91 V.]
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Textbook Question
A metal forms the fluoride MF3. Electrolysis of the molten fluo- ride by a current of 3.86 A for 16.2 minutes deposits 1.25 g of the metal. Calculate the molar mass of the metal.
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Textbook Question
A sample of impure tin of mass 0.535 g is dissolved in strong acid to give a solution of Sn2+. The solution is then titrated with a 0.0448 M solution of NO3-, which is reduced to NO(g). The equivalence point is reached upon the addition of 0.0344 L of the NO3- solution. Find the percent by mass of tin in the original sample, assuming that it contains no other reducing agents.
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Open Question
A 0.0251-L sample of a solution of Cu+ requires 0.0322 L of 0.129 M KMnO4 solution to reach the equivalence point. The products of the reaction are Cu2+ and Mn2+. What is the concentration of the Cu+ solution?