ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: dfgjgddjidfg on November 09, 2012, 10:42:59 pm
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how do i do it?
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That one was so hard!
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My teacher showed me this.
Q= It
= 4200 C (This is the total Charge)
Now the charge on one electron = -1.6 * 10^-19 (From page 5 of the data booklet)
Sooo, the N(e-) = total charge / charge on one electron
N(e-)=4200/(-1.6 * 10^-19) = 2.625 * 10^22 (Note capital N = number not mole)
We can see that n(Cu)=1.34/63.5 = 0.0211 mol, and since 2 mol of e- are required for 1mol of Cu to be formed, the amount of electrons reacting are 2* n(Cu) = 0.0422mol.
Avagadro's constant (NA) = Number of particles/number of mol ---------> NA =N/n
So NA = ( 2.625 * 10^22)/0.0422 = 6.22 * 10^23
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thanks once again :p, i just had trouble finding the number of particles,so is that the formula N(e-) = total charge / charge on one electron for finding the number of electrons
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Well yeh! It's like you have a bag that weighs 50g, and you know that each licorice bullet weighs 2 grams, the amount of licorice bullets = 25!
If you have a total charge of 50 and you know that each electron has a charge of 2, you know there are 25 electrons!
So it is total charge/ charge of one electron (-1.6*10^-19)