Answer:
38 electrons
Explanation:
From Faraday's first law of electrolysis which states that during electrolysis, the mass of a substance deposited at the electrode is proportional to the quantity of electricity passing through it. Mathematically , M ∝ Q
but M = zQ and from electricity, Q =It, hence the equation becomes M = zIt.
where M = Mass of substance deposited in g, and Q =Quantity of electricity in coulombs(C)
I = current in ampere(A)
t = time in seconds
z = Chemical Equivalent in g/C
hence, given t = 1.25 ps and i = 4.8 μA
Using Q = It = 1.25 ps × 4.8 μA , converting the ps (pico secs) to secs and micro ampere to ampere, Q = 1.25 × 10-12s × 4.8 × 10-6A = 6 × 10-18C
From 1 mole of electron is equal to the quantity of charge which is also equal to 96500C/mol,
Hence, number of moles of electrons = 6 × 10-18C / 96500C/mol
number of moles = 6.218 ×10-5 × 10-18 = 6.218 × 10-23moles
Recalling that, number of moles = number of electrons / Avogadro's constant and Avogardos constant = 6.023 × 10raised to the power of 23/mol
number of electrons = number of moles × 6.023 × 1023/mol
number of electrons = 6.218 × 10-23moles × 6.023 × 1023/mol = 37.50 which is approximately 38
Hence 38 electrons moved past the fixed reference point.