What is the total negative charge, in coulombs, of all the electrons in a small 1.20 g sphere of carbon? One mole of C is 12.0g, and each atom contains 6 protons and 6 electrons. Attempted to calculate the total number of electrons first and then using that to calculate the total negative charge. Came out with 8475.4, but MP says it is wrong.

-57792 C

Explanation:

Recall that in one mole of a substance there are an Avogadro number of molecules. That is:

 molecules

therefore, in 1.2 g, there would be ten times less molecules than in the 12.0 g mole, that is:    molecules.

Now, each C there are 6 negative charges, then, the number of electrons will be six times the number of C molecules, that is:  

 electrons.

Now we multiply this number times the charge of an electron , and we obtained the total negative charge of the carbon sample:

Total negative charge is:

therefore the total negative charge is: -57792 C

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