[slu1986]

I am trying to find out how to get average current in amps and milliamps and total coulombs passed..can someone please get me started on the right path as what to do? All of my data is below. I would appreciate it thank you. 

Here is my data:   copper   electrodes             Zinc      Electrodes
                                1          2                     1             2
wt of electrodes
before electrolysis= 19.527 g  19.254 g          12.559 g   12.308 g

wt of electrodes
after electrolysis =  19.501 g  19.276 g          12.512 g   12.315 g

change in weight =  0.0260 g  0.0220 g          0.0470 g   0.00700 g

Mols Electrolyzed=  4.09*10^-4 3.46*10^-4  7.19*10^-4  1.07*10^-4

# of Equivalents = 8.18*10^-4 6.92*10^-4   1.44*10^-3  2.14*10^-4

Faradays required= 8.18*10^-4  6.92*10^-4  1.44*10^-3  2.14*10^-4

Coulombs required=  78.9 C       66.8 C             139 C      20.7 C

Avg current in = ?
milliamps

Avg Current in = ?
amps

Starting Time = 1:50

Ending Time = 2:50

Electrolysis Time
in seconds   =  3600 sec

Total Coulombs
passed (amps x sec) = ?

 

[cimon9999]

hi,

I'll attempt to answer. I presume this is an electroplating reaction?

What appears to have happened is the dissolution of .026g of your Copper anode by: Cu(s) → Cu2+(aq) + 2e–. 0.026g copper is equivalent to 4.09*10-4 moles. For every mole of copper you get two moles of electrons, so you have 8.18*10-4moles of electrons which is equal to 78.8 Coulombs. The electrons should travel to the electrode and recombine with the Cu2+. The electrode should have increased by .026g but only increased by .022g. I don't know if that's due to experimental error or what.

Amps is short for Amperes - the unit of electrical current. That is measured in Coulombs/second. If the reaction took 3600 seconds then it seems fairly straightforward to divide the Coulombs - let's go with the higher 78.8C - and get 0.0219A or 21.89mA. Which is why I'm a bit confused with the order of the questions.

Chemistry isn't my area, so perhaps someone with more knowledge will help you more. Thought I'd chip in because Chemical Forums has been helpful to me!

[slu1986]

I appreciate your help, but I emailed my teacher and asked him and he told me for the current in milliamps you use the reading from the ammeter which was 19 milliamps and to get the current in amps you just divide 19 by 1000 which is equal to 0.019 amps.  I hear ya on chemistry not being your thing, it's not mine either which is why I always have questions about it.  Thank you for attempting to answer my question 

[Borek]

I haven't checked numbrs, but cimon approach seems to be correct.

No idea why you were asked to weight electrodes and do all these things, if the answer is "write down what ammeter shows". Don't you think there is something wrong?

[slu1986]

I haven't checked numbrs, but cimon approach seems to be correct.

No idea why you were asked to weight electrodes and do all these things, if the answer is "write down what ammeter shows". Don't you think there is something wrong?

Our data sheet that we are turning in asks for all that and so does our lab manual.  The reason for recording the weight of the electrodes Copper and Zinc was so we could record the change in weight from the weight of electrodes before electrolysis - weight of electrodes after electrolysis.  From there we used the change in weight to determine the moles electrolyzed.  We used moles electrolyzed to find the number of equivalents and then from there we used this to calculate Faraday's required and Coulomb's required etc... Then we used the ammeter reading for avg current in milliamps and then divided by 1000 to get average current in amps.  Then it asked us for the starting time of the electrolysis and finishing time which I recorded to 1 hr.  Then the electrolysis time in seconds = 3600 sec and total Coulombs passed (amps x's seconds) = 0.019 amps * 3600 sec = 68.4 C passed.  I have no idea if anything is wrong in this, I just did what my teacher told me to do.   

[Borek]

OK, so what was the purpose of the whole experiment? I am asking because it looks to me like you have just blindly followed the procedure, not knowing what you are doing and what for.