[SpottedAng]

I've been attempting to find out how to do this in my chemistry books for hours and no avail...

If you are given a certain charge of an electron sample, how do you find out how many electrons are in that specific sample?  And after you find the number of electrons, how do you go about finding the mass? Thank you!!

[Demotivator]

What do you mean by electron sample? give an example.

[Donaldson Tan]

If you are thinking along the line of an anion, eg. Cl^-

1- would means the chlorine atom gains one additional electron. In its neutral charge state, it has 17 electrons already. Hence, the chloride anion would have 18 electrons in total.

Since the mass of an electron is 1/1840 of the mass of a proton, adding an electron hardly changes the atomic mass.

[SpottedAng]

All the question says is:

A sample of electrons is found to have a total charger of -5.4475X10^10 C. How many electrons are in this sample?


I still can't find it in the book!!  

[Demotivator]

Ok
There are 96500 Coulombs of charge per mole of electrons.
5.4475X10^10 C/96500 C/mole = 5.65x10^5 moles of electrons.
One electron has mass of 9.109X10^-31 kg
One mole = 6.022X10^23 electrons
So you can figure the total mass.

[SpottedAng]

I'm still confused... I'm not trying to figure out the mass... I need to figure out how many electrons there are..

Thank you for all the help, I just get confused really easy when it comes to calculations.  

[Demotivator]

There are 96500 Coulombs of charge per mole of electrons.
5.4475X10^10 C/96500 C/mole = 5.65x10^5 moles of electrons.
Each mole has 6.022X10^23 electrons.
Therefore
number of electrons =  5.65x10^5 moles x 6.022X10^23 electrons/mole = 3.4x10^29 electrons

[Donaldson Tan]

A sample of electrons is found to have a total charger of -5.4475X10^10 C. How many electrons are in this sample?

Faraday's Constant, F, corresponds to the total charge of 1 mole of electrons.

F = 96500 Columb Per Mole

No. Of Moles of Electron In The Sample
= Total Charge / Faraday's Constant
= 5.4475X10^10 / 96500

No. of Electrons In The Sample
= No. of Moles X Avagadro's Constant
= (5.4475X10^10 / 96500) X (6.023X10^23)

[ssssss]

All the question says is:

A sample of electrons is found to have a total charger of -5.4475X10^10 C. How many electrons are in this sample?


I still can't find it in the book!!  

Ok if you want a more simple way.

As you know charge on one electron in 1.6x10^-19c,so 1st calculate the number of electrons by Dividing the number the charge by charge on 1e and then calculate the Moles.1 mole of e = 6.023x10²³ e.

But this will be somewhat more time consuming.