Galvanic Cell Help! (1 Viewer)

[Abtari]

hi there,

just one question i am confused about...

in a Zn|Zn++ and Cu|Cu++ galvanic cell, because Zn is more electropositive than copper, it gets oxidised and thus there is electron flow from the zinc terminal (anode) to copper terminal (cathode) right? Is the CURRENT flow the same, i.e. from zinc anode to copper cathode?

If you set up this experiment and attach an ammeter, you will find that the ammeter has a positive reading with zinc/anode/negative terminal as the +ve terminal and copper/cathode/positive terminal as the -ve terminal. This means that current does flow from zinc to copper.

But, how can both current and electrons flow in the same direction... HELP.

Thanks heaps.

 

[physician]

hi there,

just one question i am confused about...

in a Zn|Zn++ and Cu|Cu++ galvanic cell, because Zn is more electropositive than copper, it gets oxidised and thus there is electron flow from the zinc terminal (anode) to copper terminal (cathode) right? Is the CURRENT flow the same, i.e. from zinc anode to copper cathode?

If you set up this experiment and attach an ammeter, you will find that the ammeter has a positive reading with zinc/anode/negative terminal as the +ve terminal and copper/cathode/positive terminal as the -ve terminal. This means that current does flow from zinc to copper.

But, how can both current and electrons flow in the same direction... HELP.

Thanks heaps.

Doesn't that mean the current flows from copper to zinc since copper now becames the anode... and zinc becomes the cathode It'll be from copper anode to zinc cathode... which is in the oppsoite direction to electron flow...

are we supposed to know about the current flow in a galvanic cell?...

 

[Will Hunting]

Hey Abtari,

Everything you have stated is correct, but you seem to be working on a wrong assumption. The ammeter measures "electron current", which "does" flow in the same direction as electrons. I'm guessing you've assumed current to be "conventional" for the purpose of this exercise, which moves in the opposite direction to electrons (Conventional current is defined as a flow of positive charge). It must be noted, however, that conventional current has no physical reality (since electrons are all that are mobile in a circuit). It is only a principle designed to explain the equivalence of moving electrons and positive charge which, although doesn't move, can be treated as doing so because of the mobility of the electrons. An ammeter is a device that measures only what is real (i.e. electron current).

 

[physician]

Hey Abtari,

Everything you have stated is correct, but you seem to be working on a wrong assumption. The ammeter measures "electron current", which "does" flow in the same direction as electrons. I'm guessing you've assumed current to be "conventional" for the purpose of this exercise, which moves in the opposite direction to electrons (Conventional current is defined as a flow of positive charge). It must be noted, however, that conventional current has no physical reality (since electrons are all that are mobile in a circuit). It is only a principle designed to explain the equivalence of moving electrons and positive charge which, although doesn't move, can be treated as doing so because of the mobility of the electrons. An ammeter is a device that measures only what is real (i.e. electron current).

thanks dude... although this was directed towards Abtari but u cleared that up for me too... sorry Abtari if u read my post and went wacko...

 

[Will Hunting]

That's cool, man. I know how tricky it can be sometimes to get these things the right way around! What your said actually makes sense in Physics, when you start talking about things like cathodes and anodes in photocells, CRTs and CROs. The most important thing to remember about galvanic cells is that "oxidation occurs at the anode and reduction occurs at the cathode". Also note that this won't change whatever cyou define current as. Hence, the electron flow direction should be thought of more in terms of this property than in terms of polarity.

 

[Abtari]

galvanic cell question

Thanks for your input guys but still a bit hazy. Let's clear it up.

just one question:
if you set up the galvanic cell as i have mentioned above with Zn as anode and Cu as cathode, then will a galvaometer placed in series deflect towards the right (direction of flow of electron current) or left (direction of flow of conventional current). My opinion is that the galvanometer should deflect left since it detects conventional current not "electron" current.

Which direction do you think?

 

[Sirius Black]

To the right.
Zinc anode is the e- provider so its supposed to be -ve; whereas Cu cathode is +ve as it accepts e-s. The actual eletron flows from anode to cathode and once u connect +ve terminal to anode (which is -ve) and -ve terminal to cathode (which is +ve), the e-s flow from +ve terminal to -ve terminal therefore it results in +ve deflection i.e. to the right
Hoho hope it helps(p.s. I think you'd better forget about the so-called conventional current, coz in fact, current is defined as the movement of electrons. you only need to take serious consideration about electrons and conventional current in phys if you are doing M&G)

 

[Abtari]

To the right.
The actual eletron flows from anode to cathode and once u connect +ve terminal to anode (which is -ve) and -ve terminal to cathode (which is +ve), the e-s flow from +ve terminal to -ve terminal therefore it results in +ve deflection i.e. to the right

when you say connect +ve terminal to anode, are you talking about the terminal of a galvanometer or what? this is not clear...

 

[Sirius Black]

sorrie for my unclear statement above. The terminals i mentioned above did refer to teh galvanometer

btw, here is another q- did u use ammeter or voltmeter in the expt - does it matter which one u used(I know Voltmeter could tell u the E_cell,but what if i only want to know wether my cell couples will conduct electrivity or not)?

 

[jarro_2783]

if you want to know whether it conducts then I suppose either will work because a voltmeter will tell you the voltage across the cell, and an ammeter will tell you how much current is flowing.
Depending on the type of voltmeter you use, some can't be negative because the needle only has a positive reading. So if it doesn't read try switching the terminals.

 

[:daryl]

ummmm. yus dat hav domne da 1st assesment at school, is it da battery one? im doin it at tafe n wer behind n always catching up to yus who go to school. nyways has anyone done da battaery assesment, if so can u help me out wid resources? thanx

 

[Pace_T]

ummmm. yus dat hav domne da 1st assesment at school, is it da battery one? im doin it at tafe n wer behind n always catching up to yus who go to school. nyways has anyone done da battaery assesment, if so can u help me out wid resources? thanx

sure thing mate,
im pretty sure this is in the syllabus, under the electrochemistry topic.
if you look in the resource section on the main page you can find numerous notes on the core topic (production of materials) and under the electrochemistry section of peoples notes there will be a major dot point in which students have to assess 2 batteries from a selection of about 5-6 or somewhere near there
the assessment includes practicality, economic, chemistry (chemistry behind it) and one more i think (i dont know if you have the same assignment??)
the numerous notes should provide all the info you need.

hope i helped

 

[taxman]

sure thing mate,
im pretty sure this is in the syllabus, under the electrochemistry topic.
if you look in the resource section on the main page you can find numerous notes on the core topic (production of materials) and under the electrochemistry section of peoples notes there will be a major dot point in which students have to assess 2 batteries from a selection of about 5-6 or somewhere near there
the assessment includes practicality, economic, chemistry (chemistry behind it) and one more i think (i dont know if you have the same assignment??)
the numerous notes should provide all the info you need.

hope i helped

Goddamn Pace...so lazy, referring people to the notes section

 

[Rax]

Um eh what is a galvanometer..... (tell me its a volt or ammeter)
but seriously I dont remeber any reference to galvanometer in my text book or syllabus
thanks in advance

 

[rama_v]

Um eh what is a galvanometer..... (tell me its a volt or ammeter)
but seriously I dont remeber any reference to galvanometer in my text book or syllabus
thanks in advance

a galvanometer is just a device that measures current flow. Its basically an ammeter except it can usually measure much smaller current flows (i.e. in milli or microamps)

 

[n a + a l i e]

^__

and what's a terminal?

 

[Riviet]

A terminal is where you insert the wire to connect the galvanometer to the half cells.

 

[mitsui]

like.. anode and cathode?? Oo

 

[insert-username]

Galvanometers aren't mentioned in the syllabus as I remember. Terminals are connected to the electrodes.


I_F

 

[Riviet]

Yep that's correct.