Electroplating - Video Tutorials & Practice Problems

Electrical Current (A)

Now, electroplating is the use of electrical current to coat metal cations onto a metal electrode. Now, here when we say electrical current, this is the rate at which electrons move from electrode to electrode in a closed complete circuit. So we're talking about electrons traveling from the A node to the cat. Now here, remember when we say rate rate is just amount of something over changing in time. Now here, the si unit for electrical current is pi or amps which uses capital A. And what's important here is that one here is equal to one Coolum per second. So this is going to be an important conversion factor when we're talking about the calculations involved with typical electroplating questions.

Electroplating Example

Here, it says, determine the electrical current produced if a charge of 4.14 times 10 of the three poum passes through a wire for 15 minutes. All right. So, remember electrical current is in amps and remember that one amp is equal to one Coolum per second. So, what we need to do here is we need to find units of columns and units of seconds combine them together to find our amps, which is equal to our current. All right. So here we already have the, uh, the Coombs, which is 4.14 times 10 to the three Coombs. All we have to do at this point is figure out from 15 minutes. How many seconds do we have? So, we have 15 minutes. Remember one minute is equal to 60 seconds. Minutes cancel out here. And we're gonna have 900 seconds. Take those 900 seconds, plug it here on the bottom. So that's gonna give me 4.6 cool LS per second or 4.6 amps. This would be our electrical current.

Electrochemical Stoichiometry

Now, electrochemical stoichiometry deals with calculations in electrochemical cells that involve current and charge. Now, we're gonna say this version is used when the given amount is in units of time. So hours, days seconds, what have you? Now here, they're gonna give you units of time. So we start out with seconds of given. So if they give it to you in any other type of units of time, you have to convert them to seconds. Once you have seconds of given, we utilize current with this. Remember, current is the same thing as peers, which is koms per second, we would utilize seconds with current and that'll help us isolate charge. So we have charge of given charge here, we just use Kums as its units. From this point we'd interact with Frise constant. Remember Frase constant is 96,045 coulombs per moles of electrons interacting with this would then give us moles of electrons given at this point. We need to go for moles of electrons and we need to make a jump to an area where we don't know as much. So we're gonna go to an area of unknown, this kind of a leap of faith, this jump will take us from moles of electrons to moles of unknown. Now here, when we make this jump, we actually have to do a mole to electron comparison. In this step, we have to use the coefficients in the balance equation. So for example, one mole of your particular element has a transferring of three moles of electrons. So it'd be one mole of element per three moles of electrons. This is the mole to electron comparison you'd have to do. And then at this point, if you know the moles of your substance, we all know how to do different types of conversions. You can change those moles into grams, you could change them into molecules, you could change them into ions, you could change them into kilograms, right? But this is the setup that you utilize when they're giving you in the beginning units of time.

Electroplating Example

We're told that gold can be plated out of a solution containing gold three ion based on the following half reaction. Half reaction here is that says that for every one mole of gold three ion, we absorbed three moles of electrons to give us one mole of gold solid. Now, here it says what mass of gold is plated by a 41 minute flow of 6.8 amps in terms of current. Now, here they're giving us units of time in the beginning. It's up to us first to change these minutes of given into seconds of giving. So we're gonna start out by saying we have 41 minutes. We need to convert it into seconds of given for every one minute. It's 60 seconds. Now that we have seconds, we're gonna introduce current. Now, remember current or amps. So one amp is equal to one coulomb per one second. So you gonna give me 6.8 amps. Here, it's equal to 6.8 coulombs per one second. We want second to slot. So we're gonna put the one seconds on the bottom 6.8 cool ones on the top. Now that we have cos we're gonna have to go from seconds of given to charging given. And that's what we just did here. Next, we're gonna go from charger given to moles of electrons are given by utilizing Ferdi constant, 96,045 coulombs per one mole of electrons. Now that we have moles of electrons given, we're gonna make the jump to moles of unknown. So we have to look at the coefficients and the balance equation. And it is for every one mole of my solid, I have three moles of electrons. So it's three moles of electrons for every one mole of gold. So moles of electrons can't s now I have moles of gold here, we want mass. So we're gonna end at grant. So last thing is we're gonna say for every one mole of gold according to my periodic table, we're gonna say the atomic mass of gold is 1 96.967 g of gold. So here when we work this out, we're gonna get 11.383 g of gold if we want to do it, in terms of sick figs, this has two sick figs, this has two sick figs. So you can round to just 11 g of gold. So here this would be our final answer.

Stoichiometric Chart and time.

We're going to say when the initial mass for half reaction is given, we can utilize the mass version of the stoy metric chart to find time. So here we're gonna say this version is used when the given amount is a unit of mass. Here, we're going to start out with grams I've given and with these grams I've given, we know how to go from grams to molts. We use the atomic mass of the oven. Now we're going from moles of given to moles of electrons given this requires us to do a jump when we do this jump in actuality, what we're doing is a mole of your element to moles of electrons transferred. So it's a mole to electrons comparison here, we'd have to use the coefficients in the balance equation. Now, once we know the moles of electrons, we can utilize fries constant and this will help us find the charge of our unknown. And once you know the charger you are unknown, you can use current, which will then help you find seconds of unknown. So this is the chart we utilize when given our mass initially

Electroplating Example

How much time in hours would it take to plate out 42.1 g of nickel using a current of 3.08 amps. So here we have one mole of nickel, two plus ion reacting with two moles of electrons to give us one mole of nickel solid. Here, we're gonna start out with grams of given 42.1 g of nickel. And we're gonna change those grams of given into moles of given grams go on the bottom. So they can cancel out one mole of nickel goes on top. Here, if we look at the periodic table, we'll find the atomic mass of nickel that comes out to 58.693 we now have moles of given. So the next step is to get moles of electrons of given to do that. We look at the coefficients in the balanced equation. For every one mole of nickel solid, there's two moles of electrons involved. So for every one mole of nickel, there's two moles of electrons. So moles of nickel are gone. Now we need to go from moles of electrons of given to charge of unknown. We do this by utilizing FAY constant. So for every one mole of electrons, it's 96,045 pull ups. Now that we have charge of unknown we can find here. Um Let's see from this, we can utilize our current and that'll help me find seconds involved. Remember, amps is equal to 3.08 here. Coombs per second. So we put the 3.08 columns on the bottom one second on the top, we have seconds now, so now just becomes converting seconds into minutes and then into hours. So we're gonna say we have 60 seconds for every one minute we have here, one hour is equal to 60 minutes. Everything here cancels out. So at the end, we're gonna get 12.483 hours. Here are numbers in the questionnaire 366. So I'm gonna round this to 12.5 hours. So this would be our final answer.

Cu²⁺ is reduced to Cu(s) at an electrode. If a current of 1.25 A is passed for 72 hours, what mass of copper is deposited at the electrode? (MW of Cu: 63.55 g/mol)

• A. 91.5 g
• B. 55.8 g
• C. 83.1 g
• D. 110 g

A solution of Mn⁺⁵ is used to plate out Mn in an electrochemical cell. If a total of 1.13 g of Mn is plated out in a total time of 1600 seconds, what was the electrical current used? (MW of Mn is 54.94 g/mol)

• A. 3.5 A
• B. 6.2 A
• C. 1,8 A
• D. 7.7 A