Why do carbon electrodes conduct electricity in water?

[NanakiXIII]

We did an experiment in chemistry class today, where we had to see whether certain substances dissolved in water conducted electrcity. For this we put carbon electrodes in the liquid and connected them, but that's not important. My question is, how did the carbon conduct the electricity? From what I've had in class so far, it's not supposed to.

 

[The Bob]

We did an experiment in chemistry class today, where we had to see whether certain substances dissolved in water conducted electrcity. For this we put carbon electrodes in the liquid and connected them, but that's not important. My question is, how did the carbon conduct the electricity? From what I've had in class so far, it's not supposed to.

The electrodes are made of Graphite. Graphite is a form of carbon. Carbon atoms try to form 4 bonds with each other, in graphite and diamond. If you look at the structure of graphite, each carbon atom bonds with 3 others. This means there is a free electron that can pass the electrical current in between the layers. As diamond uses all four bonds, it can not.

Graphite and Diamond are both forms of carbon.

The Bob (2004 ©)

 

[NanakiXIII]

Ah, I see. Thanks.

 

[The Bob]

Ah, I see. Thanks.

No Porblem.

The Bob (2004 ©)

 

[kittyzmad2k7]

why does graphite conduct electricity yet diamond does not? and also, why is graphite soft and diamond hard if they are both substances of carbon?

 

[dx/dy=?]

The solution to the question on conductivity has already been answered by The Bob (above), if you want more detail on this look into the VB (valance bonding) theory, or VSEPR for carbon, and then look at the way carbon bonds to form graphite and diamond, and the manner in which free electrons can move from valance bands to conduction bands and acceptor bands.
That will also give insight into why diamond is extremely hard and why graphite is soft.
Their external structure reflects their internal atomic structure.

 

[dx/dy=?]

In fact, any good Inorganic textbook will give complete in-depth views on these issues.

 

[kittyzmad2k7]

thank you huni

thank you, your answer has reeli helped me Bob and dx/dy=?. i wouldn't have been able to have answered my chemistry research question without your help. now that i know i won't forget, thank you xxx
the question i asked want a GCSE coursework topic it was just something we had to learn so that the teacher didnt have to teach us

 

[kittyzmad2k7]

the question i have been asked to research is:
How the structure of a substance can be used to explain its properties.
can anyone help me please?
it wud be really appreciated

thnx hunis xxxxx

 

[haiha]

You can take diamond and graphite for examples. They are all carbon atom. In diamond, each C atom has 4 bonding with adjacent ones. That is the sp3 hybrid. So diamond has the spatial structure and it is very hard and does not conduct electricity. In other hand, carbon atoms in graphite has only 3 bonds and the 3 bonds are in a plane because it is the sp2 hybrid. So in graphite, carbon atoms create many planes and each plane can slide against the adjacent ones, so graphite is soft. The non-bonding electrons of carbon in graphite is the reason for electricity conduction.

 

[Gokul43201]

the question i have been asked to research is:
How the structure of a substance can be used to explain its properties.
can anyone help me please?
it wud be really appreciated

thnx hunis xxxxx

Hi kittyzmad,

Please read our forum guidelines. If you have homework or coursework related questions, please post them in the appropriate subforum of the Homework & Coursework Section. Also, when you ask for help, you are required to show us what effort you have made towards answering the question, before we can help you.