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Chemistry F334 Calculations

Please can someone explain to me how question 2.) C.) ii.) works.

Much appreciated!
F334 JAN 2010.pdf200.9KB
Original post by thelion0
Please can someone explain to me how question 2.) C.) ii.) works.

Much appreciated!


It's just the difference between the electrode potentials of the two half cells
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thelion0
OP
11
Original post by charco
It's just the difference between the electrode potentials of the two half cells


you answered the wrong question.
Original post by thelion0
you answered the wrong question.


ahhh yes, so I did :colondollar:

2Cii) Work out the moles of thiosulphate: 0.0205 * 0.2

Using the equations:

mol thiosulphate/2 = moles of iodine
moles of iodine * 2 = moles of copper

Hence moles of thiosulphate = moles of copper ions.

To find the total moles of copper ions multiply by 10 to scale up to the 250ml solution.

Then moles of copper ==> mass of copper

Then percentage = 100 * mass of copper/mass of sample
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thelion0
OP
11
Original post by charco
ahhh yes, so I did :colondollar:

2Cii) Work out the moles of thiosulphate: 0.0205 * 0.2

Using the equations:

mol thiosulphate/2 = moles of iodine
moles of iodine * 2 = moles of copper

Hence moles of thiosulphate = moles of copper ions.

To find the total moles of copper ions multiply by 10 to scale up to the 250ml solution.

Then moles of copper ==> mass of copper

Then percentage = 100 * mass of copper/mass of sample


haha! thank you very much I understand it now. its the calculations that get me each time..

:colondollar:

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