# Edexcel IGCSE Chemistry Paper 2C-4CH1 12th June 2019Watch

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6 days ago
#21
can someone explain the second part of the last question it was the moles of the bleach
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6 days ago
#22
Yeah, I realised the same thing. Other than that CGP Guides are excellent. This is strange though because it is not on the CGP guide, but it is on the syllabus.
But yes, its only two marks...
(Original post by mp99)
Colour change from ethanol to ethanoic acid is orange to green (not in the CGP guide) i put colourless to black
1
6 days ago
#23
i said it gets darker cos theres a higher concentration in a smaller volume so it appears darker
Anyone know why the mixture got darker and why less No was produces?
2
6 days ago
#24
if you already have the moles of chlorine from the conc = mol / vol formula, you can see that the ratio of bleach to Cl is 1:1. Therefore the number of moles in bleach is the same as the number in carbon. Then you have to convert the volume of bleach they give you (4cm^2) into decimeters so 4/1000. eventually, you get (Moles of Bleach) / (Volume of Bleach [in dm^2]) to give you something around 0.650 mol/dm^2 (something around that... I can't quite remember...
(Original post by mg45)
can someone explain the second part of the last question it was the moles of the bleach
0
6 days ago
#25
UNOFFICIAL MARK SCHEME (Great paper) Enthalpy Change = -788. Last Page (a) do experiment in fume cupboard to prevent chlorine gas from being exposed in air as it is poisonous (b) 0.0025 (c) 0.0025 (d) 0.625. Why does it appear darker if there is less No2? = they particles are more tightly packed so it appears darker. That’s the difficult things I can remember if anyone needs any reassuring reply and I’ll tell you what I put!
2
6 days ago
#26
See one mole of Cl2 gives 1 mol of NAclo..hence (2.5*10 -3) gives the same amount for the bleach too.
Cross multiply and you'll find the same amount of mols
(Original post by mg45)
can someone explain the second part of the last question it was the moles of the bleach
0
6 days ago
#27
90 was anomalous for the average right
1
6 days ago
#28
Yea, I excluded from the mean calculation.
(Original post by nerddddo)
90 was anomalous for the average right
3
6 days ago
#29
I said wear gloves because it is corrosive, is that right?
0
6 days ago
#30
(Original post by Straight9dan)
UNOFFICIAL MARK SCHEME (Great paper) Enthalpy Change = -788. Last Page (a) do experiment in fume cupboard to prevent chlorine gas from being exposed in air as it is poisonous (b) 0.0025 (c) 0.0025 (d) 0.625. Why does it appear darker if there is less No2? = they particles are more tightly packed so it appears darker. That’s the difficult things I can remember if anyone needs any reassuring reply and I’ll tell you what I put!"
"why does it appear darker if there is less NO2"
it's a question on equilibrium?? all the particles are tightly packed?
0
6 days ago
#31
No it’s not a question about equilibrium , the whole point is to be able to apply your knowledge in different areas, don’t be narrow minded.
0
6 days ago
#32
Correct.
(Original post by mp99)
I said wear gloves because it is corrosive, is that right?
0
6 days ago
#33
i really wished i checked over the last page i calculated the mol wrong by accidentally not using the right volume rip
1
6 days ago
#34
(Original post by Suley143)
Correct.
Not really, its actually wear a gas mask because chlorine gas is toxic. Nothing to do with corrosivity
0
6 days ago
#35
What is the other substance other than chlorine?
(Original post by EditedRhyme)
Not really, its actually wear a gas mask because chlorine gas is toxic. Nothing to do with corrosivity
0
6 days ago
#36
you'll probs get some marks for working
(Original post by LiamGor)
i really wished i checked over the last page i calculated the mol wrong by accidentally not using the right volume rip
0
6 days ago
#37
(Original post by EditedRhyme)
Not really, its actually wear a gas mask because chlorine gas is toxic. Nothing to do with corrosivity
Last edited by leo1233; 6 days ago
2
6 days ago
#38
yea probably
(Original post by joejoeeames)
you'll probs get some marks for working
0
6 days ago
#39
He's talking about when handling acids and bleach...
which are corrosive.

but I didn't put that answer
(Original post by leo1233)
1
6 days ago
#40
(Original post by joejoeeames)
He's talking about when handling acids and bleach...
which are corrosive.

but I didn't put that answer
you should have hahaha
0
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