The electrodes on batteries are labeled + and. The is labeled and occurs there.

Question

The electrodes on batteries are labeled + and. The is labeled and occurs there. Copper metal is purified by electrolysis. How much copper metal could be produced from copper9110 oxide by applying a current of 10.0 amps at the appropriate negative potential for 12.0 hours? Which of the following is not an advantage in using hydrogen fuel cells rather than gasoling engines in vehicles? It is more efficient use of chemical energy. Only water is emitted as a reactant product. Imported petroleum is less dangerous than the gasoline tank. Hydrogen is an abundant element.

Explanation / Answer

Answer – 24) We know in the batteries electrode are labeled as + and – ve. The batteries containing the electrochemical cells and the negative electrode is called anode and positive electrode called as cathode. On the cathode there is reduction and on the anode there is oxidation, so the correct filling the blanks for the given statement is as follow –

The electrodes on batteries are labeled as + and – ve. The cathode is labeled positive and reduction occurred there.

So answer is option c) cathode/positive/reduction

25) We are given, Cu metal is purified from the CuO, means

Cu2+ + 2e- -----> Cu

Current = 10.0 A, time, = 12.0 hrs

First we need to convert the time hrs to s

We know,

1 hrs = 60 min

1 min = 60 s

So, = 12 hrs * 60 min / 1hrs *60 s / 1min

      = 43200 s

We know,

Electric charge = current * time

                         = 10.0 A * 43200 s

                        = 432000 C

Now we need to calculate the moles of electrons

We know

96485 C = 1 moles of electrons

So, 432000 C = ?

= 4.48 moles of electrons

We also know,

2 moles of electrons = 1 moles of Cu

So, 4.48 moles of electrons = ?

= 2.24 moles of Cu

So, mass of Cu = 2.24 moles * 63.546 g/mol

                         =142 g

So, c)142 g of Cu metal could be produced.

26) We know the hydrogen fuel cell is more efficient than gasoline in the vehicle, it is also not harmful and only water as byproduct. We also know the hydrogen is abundance element, but it is very light in weight, so there is problem of the storage and transport, so answer for this one as d) Storage is less dangerous than gasoline tanks.

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