Electroplating is a widely used process. One of the most popular electroplating processes involves the plating of two metals, nickel and chromium, in separate vats. Nickel is plated first because it adheres better to iron, then the object is moved to a second vat where a layer of chromium is plated. The half-reactions occurring in each vat are shown below:
Plating of Nickel Ni2+(aq) + 2 e- „³ Ni(s)
Plating of Chromium Cr2O72-(aq) + 14 H+(aq) + 12 e- „³ 2 Cr(s) + 7 H2O(l)
1. 1. The power supply used in commercial electroplating provides each vat with approximately 1.50 x 103 A of current for 30.0 minutes. In which vat (Ni or Cr) is the greatest mass of metal deposited on a car bumper? Justify your answer.
2. 2. To save on production costs, most automobile bumpers are never coated with more than 200 g of chromium. Determine how much time a standard bumper should be immersed in a chromium vat.
I got number 1 i just need help with number 2 please and thank you
It takes 96,485 coulombs to plate 1 equivalent Cr(52/6= about 8.67 g). To plate 200 g will require how many C?
96.485 x (200/8.67) = ? C
Then amperes x time = C
You know A and C, solve for time (in seconds)
To determine the amount of time a standard bumper should be immersed in a chromium vat, we need to use the concept of Faraday's Law of Electrolysis. This law relates the amount of substance deposited during electrolysis to the amount of electrical charge passed through the electrolyte.
The equation for Faraday's Law is as follows:
mass (in grams) = (molar mass of the substance) * (charge passed) / (Faraday's constant)
In this case, we need to determine the time required for a certain amount of chromium to be deposited on the bumper, so let's rearrange the equation as follows:
time (in seconds) = (mass (in grams) * Faraday's constant) / (molar mass of the substance * charge passed)
Now, let's proceed with the calculation using the given values:
Mass of chromium deposited = 200 g
Molar mass of chromium (Cr) = 52 g/mol (approximate value)
Charge passed = 1.50 x 103 A * 30.0 minutes * 60 seconds/minute
First, we need to convert the given mass of chromium to moles:
moles of chromium = mass of chromium deposited / molar mass of chromium
= 200 g / 52 g/mol
= 3.846 moles
Now, let's calculate the time required using the rearranged equation:
time = (mass * Faraday's constant) / (molar mass * charge passed)
= (3.846 moles * 96485 C/mol) / (52 g/mol * 1.50 x 103 A * 30.0 minutes * 60 seconds/minute)
To simplify the calculation, let's convert minutes to seconds:
time = (3.846 moles * 96485 C/mol) / (52 g/mol * 1.50 x 103 A * (30.0 * 60) seconds)
Now, we can plug in the values and calculate the time:
time = (3.846 * 96485 C * s / mol) / (52 g/mol * 1.50 * 103 A * 1800 s)
≈ 470 seconds
Therefore, a standard bumper should be immersed in the chromium vat for approximately 470 seconds (or 7 minutes and 50 seconds) to deposit a maximum of 200 grams of chromium.