Please show all calculations for question 3, and answer question 4 QUESTION 3 A

Question

Please show all calculations for question 3, and answer question 4

QUESTION 3 A student set up an electrolytic cell similar to the one in the Electrolysis experiment to collect hydrogen gas over water in a burette, using a small strip of lead metal as the anode (instead of copper). Before the electrolysis, the mass of the lead strip was 8.617 g. A current of 121.1 mA was applied for a period of 3600 seconds, during which time some of the lead metal was oxidized to lead (2+) What was the mass of the lead metal strip at the end of the electrolysis? Final mass of lead strip-?g (calculate your answer in grams, but do not include the units when submittng your response) QUESTION 4 Which of following would provide a low resistance circuit during the electrolysis experiment? OA The nichrome wire is placed far inside the buret. 8. The copper wire is placed on the opposite side of the beaker from the buret . Hydrogen gas is allowed to escape from the burette A large diameter copper wire is used. A low current is applied O D OE

Explanation / Answer

3) Quantity of electricity passed = (121.1 mA)*(3600 s) = (121.1 mA)*(1 A/1000 mA)*(3600 s) = (0.1211 A)*(3600 s) = (0.1211 A)*(1 C.s-1/1 A)*(3600 s) = 435.96 C.

We know that 96485 C of electricity = 1 mole of electrons. Therefore,

435.96 C of electricity = (435.96 C)*(1 mole electrons/96485 C) = 0.004518 mole electrons.

Consider the reduction reaction.

Pb2+ (aq) + 2 e- ---------> Pb (s)

We can see that 1 mole Pb = 2 moles electrons. Therefore,

0.004518 mole electrons = (0.004518 mole electrons)*(1 mole Pb/2 mole electrons) = 0.002259 mole Pb.

Atomic mass of Pb = 207.2 g/mol.

Mass of Pb lost = (0.002259 mole)*(207.2 g/mol) = 0.468 g.

Final mass of the lead strip = (8.617 – 0.468) g = 8.149 g.

Input the final answer as 8.149 (ans).

4) Copper wires are excellent conductors of electricity. A good conductor is characterized by having a low resistance. A small diameter of the wire is essential for good conductivity. Hence, the second option is the correct answer.

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