I already figured out 1. If someone could help me out with the 2nd problem, that

Question

I already figured out 1. If someone could help me out with the 2nd problem, that would be great!! Thank you!

l. Consider the following electrochemical cell: Al(s) I Al (0.155 M) ll H (aq) (0.00233 M), Mno (aq) (0.0377 M), Min taco (0.0168 M)IC (graphite) 4 a Write a balanced equation for the redox reaction taking place in this cell. (5 pts) b) Calculate Ecell at 25°C. (10 pts) 2. The following reaction is generated in an electrolytic cell: 3+ 2 Als) 3 H 6 H 2 Al (aq) 20g) (aq) If the reaction is driven by a 1.24 A constant-current battery for 18.3 min, calculate the volume of hydrogen gas (at STP) and the mass of aluminum dissolved. (10 pts)

Explanation / Answer

current = i = 1.24 A

time = t = 18.3 min = 18.3 x 60 = 1098 sec

F = faraday = 95485 C

equivalence weight of H2 = 2

weight of H2 deposited = E x i x t / F

                                     = 2 x 1.24 x 1098 / 96485

                                   = 0.0282 g

moles of H2 = mass of H2 / molar mass

                  = 0.0282 / 2

                = 0.0141

at STP : P = 1 atm

              T = 273 K

P V = n R T

1 x V = 0.0141 x 0.0821 x 273

V = 0.316 L

volume of H2 = 0.316 L

54 g Al dissolved ----------------------> 3 x 22.4 L H2

x g Al dissolved -----------------------> 0.316 L H2

x = 54 x 0.316 / 3 x 22.4

x = 0.254 g

mass of Al dissolved = 0.254 g

     

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