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2016 IGCSE Chemistry Paper 2 Unofficial Mark Scheme 2016

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Reply 60

rcmack

Original post by pendos

Defo 180

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yes, but do you remember the previous parts of the question? or what question number it was?

Reply 61

Ashnii34

Original post by Lelanor

I got 180g. 20 F of electricity = 3 moles of electrons. 3 moles of electrons: 1 mole of aluminium (from half equation given). 20/3 moles of aluminium made. Mass = moles × Mr = 20/3 x 27 = 180 g

Ikrr!! I did the same exact thing I wonder how people got 540 lol

Reply 62

rcmack

Original post by pendos

Common misconception, it turns acidic

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i think both could be right, when neutralised it will be orange (pH 7), but if it turns slightly acidic, it will be red

Reply 63

Niclewis

Original post by Nurne

C8H18 +8 1/2O2 -> 8CO + 9H20

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nope you're wrong once again. It produces carbon monoxide AND carbon AND water AND carbon dioxide

Reply 64

Nurne

Original post by pendos

Common misconception, it turns acidic

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Search definition no excess H+ or OH- ions present. Meaning neutral.

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Reply 65

Lelanor

Original post by Ashnii34

Ikrr!! I did the same exact thing I wonder how people got 540 lol

They probably didn't realise there were fewer moles of aluminium than electrons and just did 20 x 27 = 540. I think someone I was talking to after the exam said she didn't know how to do it so guessed the method and got that.

Reply 66

Niclewis

Original post by Nurne

Search definition no excess H+ or OH- ions present. Meaning neutral.

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i have no idea what you are going on about. You are talking down to people like they have no idea. They will accept red because it does turn slightly acidic FACT

Reply 67

Nurne

Original post by Niclewis

nope you're wrong once again. It produces carbon monoxide AND carbon AND water AND carbon dioxide

Nope.

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Reply 68

Niclewis

Original post by Nurne

Nope.

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there's not much point in arguing because you are just wrong. 100%. You think u know every answer. You don't. You're wrong.

Reply 69

Nurne

Original post by Niclewis

i have no idea what you are going on about. You are talking down to people like they have no idea. They will accept red because it does turn slightly acidic FACT

http://www.avogadro.co.uk/chemeqm/acidbase/titration/phcurves.htm

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Reply 70

Niclewis

Original post by Nurne

Fe3+ Orange/Brown precipitate
Fe2+ Dark green precipitate

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they refuse orange. It's brown.

Reply 71

username2151383

for the incomplete combustion equation did you have to make all of those products or could it just have been carbon monoxide and water??

Reply 72

Nurne

Original post by Niclewis

there's not much point in arguing because you are just wrong. 100%. You think u know every answer. You don't. You're wrong.

No, you are.

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Reply 73

rcmack

Original post by defenestrated

for the incomplete combustion equation did you have to make all of those products or could it just have been carbon monoxide and water??

im pretty sure incomplete combustion always produces carbon and co2

Reply 74

Niclewis

Original post by Nurne

http://www.avogadro.co.uk/chemeqm/acidbase/titration/phcurves.htm

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u seem to have a problem listening to people. They will accept an acidic colour because it turns slightly acidic following neutralisation because it is close to impossible to completely neutralise it 100%