champion1
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Hi! Please could you help me with this question.

A 0.80 g sample of brass was dissolved in nitric acid to produce a mixture of copper(II) nitrate and zinc nitrate. Excess potassium iodide was added and the iodine produced reacted with 35.4 cm^3 of 0.200 mol dm^-3 sodium thiosulphate solution. Determine the composition of brass as % copper and zinc.

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charco
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(Original post by champion1)
Hi! Please could you help me with this question.

A 0.80 g sample of brass was dissolved in nitric acid to produce a mixture of copper(II) nitrate and zinc nitrate. Excess potassium iodide was added and the iodine produced reacted with 35.4 cm^3 of 0.200 mol dm^-3 sodium thiosulphate solution. Determine the composition of brass as % copper and zinc.

Thanks!
.. and your ideas are?
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champion1
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(Original post by charco)
.. and your ideas are?
I think since brass hass copper and zinc, they react with the nitric acid as follows.

Cu + 4HNO3 --> Cu(NO3)2 + 2NO2 + 2H2O
Zn + 2HNO3 --> Zn(NO3)2 + H2

And then I'm stuck from there!
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GDN
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You need to know 2 further reactions 1. the reaction between Cu2+ and I- and 2 the reaction between iodine and thiosulphate After that its a normal titration calculation
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