Chromium metal can be plated onto an object from an acidic solution of dichrmonate tions. What average current is required to plate 17.8 g of chronium metal in a time of 2.20 h? ( you will need to construct your own equation for the half-reaction)
Write the equation, determine the the atoms of chronoum metal, and then from the balaced equation the number of electrons to balance the equations.
amps= 1/chargeonelectron * total charge /time
To determine the average current required to plate chromium metal onto an object, we need to first construct the half-reaction for the plating process.
The balanced equation for the half-reaction of chromium plating is as follows:
Cr2O7^2- + 14H+ + 6e- → 2Cr3+ + 7H2O
In this reaction, dichromate ions (Cr2O7^2-) are reduced to chromium ions (Cr3+) by gaining 6 electrons.
To calculate the average current, we need to know the number of moles of chromium (Cr) in 17.8 g of chromium metal. We can use the molar mass of chromium (Cr) to convert grams into moles.
The molar mass of chromium (Cr) is 52 g/mol. Therefore, the number of moles of chromium metal can be calculated as:
moles of Cr = mass of Cr / molar mass of Cr
moles of Cr = 17.8 g / 52 g/mol
Next, we need to convert the given time of 2.20 hours to seconds, as the average current is measured in amperes (A).
1 hour = 3600 seconds
Therefore, the time in seconds is:
time in seconds = 2.20 hours × 3600 seconds/hour
Now, we can calculate the average current using Faraday's law of electrolysis, which states that the amount of substance (in moles) deposited or liberated at an electrode is directly proportional to the quantity of electricity (in Coulombs) flowing through the electrolyte.
The formula to calculate the average current is:
average current (I) = moles of substance deposited / time in seconds
To calculate the moles of substance (in this case, chromium) deposited, we need to convert moles of Cr to moles of electrons using the balanced equation. Since 6 electrons are involved in the reduction of each Cr2O7^2- ion, the moles of electrons can be calculated as:
moles of electrons = moles of Cr × (6 moles of electrons / 2 moles of Cr)
Now, we can substitute the calculated values into the formula for average current:
average current (I) = moles of electrons / time in seconds
Solving the equation will give us the average current required to plate chromium onto the object.