Some AS Chemistry past paper Questions Watch

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Mccarthy
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When I was doing my A-Level Chemistry homework, I got stuck on some of the difficult questions which I hope somebody can help me to solve these problems.

1. Explain why iron can be formed by reacting iron(III) oxide with aluminium but cannot be formed by reacting iron(III) oxide with copper.
2. The spectra of sunlight and light emitted from a filament lamp are the same. Describe the main difference between the hydrogen emission spectrum and these spectra.
Also, explain the difference you have described above in terms of electron energies.

Thanks for your help.
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sazzles
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Report 16 years ago
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(Original post by Mccarthy)
When I was doing my A-Level Chemistry homework, I got stuck on some of the difficult questions which I hope somebody can help me to solve these problems.

1. Explain why iron can be formed by reacting iron(III) oxide with aluminium but cannot be formed by reacting iron(III) oxide with copper.
2. The spectra of sunlight and light emitted from a filament lamp are the same. Describe the main difference between the hydrogen emission spectrum and these spectra.
Also, explain the difference you have described above in terms of electron energies.

Thanks for your help.
1.Aluminium is more reactive than iron, so can displace it from the compound as Al3+ is smaller than Fe3+ and therefore has a greater charge densoty. Copper is less reactive than iron, so it cannot displace iron, probably because an Fe3+ ion has a greater charge density than a Cu2+ ion.
2. Not too sure about this one. I think a hydrogen emission spectra would have coloured lines, whereas sunlight spectra would be a solid bar of colours (in the visible region). This is becasue hydrogen hav discrete energy levels, so only certain wavelengths are emitted. In the sun, there are many many different elements so all wavelngths are produced.

Hope this helps.
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