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edexcel IGCSE chemistry 1CR 2016

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Reply 140
Avatar for Talha9
Talha9
2
Original post by MohaimenH
answered it before.






I got the answer as 1162 J. Added the volume of the solutions and multiplied it by 4.2 and the temp change.


Did you change mass to kg or any other in Enthalphy change ?
and when shall the student start the timer ? ( in that precipitate question ) ?
Wb chromatography ? which 3 boxes we had to tick ?
(edited 7 years ago)
Reply 141
Avatar for Talha9
Talha9
2
What was the formula for Neodymium Oxide ? was it NdO ? or i got it wrong :/ *_*
Original post by Talha9
What was the formula for Neodymium Oxide ? was it NdO ? or i got it wrong :/ *_*


I wrote Nd2O3
Original post by Talha9
What was the formula for Neodymium Oxide ? was it NdO ? or i got it wrong :/ *_*


I wrote Nd2O3 too. Neodymium fluoride (or whatever it was) had the formula NdF3, so that means that Nd must have a charge of 3 (since +3 is needed to balance -3). Since oxygen is -2 and neodymium is +3 you multiply both to get 6, which gives Nd2O3. Hope that made sense!
Original post by nusquam
I wrote Nd2O3 too. Neodymium fluoride (or whatever it was) had the formula NdF3, so that means that Nd must have a charge of 3 (since +3 is needed to balance -3). Since oxygen is -2 and neodymium is +3 you multiply both to get 6, which gives Nd2O3. Hope that made sense!


or you can just switch the valencies. :tongue:
Original post by nusquam
Okay guys, I remember some of the questions, so maybe share what you all wrote for each of them?

- Two reasons why putting the lid on the tank with the chromatography experiment in would help
- Solubility of sulphur dioxide in air and why
- Three reasons for cracking
- Which reactions for redox reactions
- Why burning C6H12S is bad


1. Because the flammable solvent would react with the Oxygen and burn
So the wind will not blow the solvent to interfere with other pigment lines.
2.
3. Abundance of large hydrocarbons
More use of smaller hydrocrabons
More demand for smaller hydrocrabons
4. 4 and 6
5. Because when S burns in air it produces SO2 which can dissolve in rain to cause acid rain, it also means that more oxygen is used and there's a higher chance of incomplete combustion, which will lead to CO being produced, which is a poisonous gas.
What were the potential problems of using lid in chromatography?
Reply 147
Avatar for Talha9
Talha9
2
Original post by Kazi Shahul
What were the potential problems of using lid in chromatography?


I wrote 1 point only :/ ( that solvent doesn't drop out ) not sure correct or wrong !

What did you write for REDOX reactions ? which 2 reactions were REDOX ?
reaction 4 and reaction 6
Guys the exam was easy besides the stupid question on the anomalous result
Im an A* chemistry student at my school if u need answers ask me 00971508955257 whatsapp
Astatine was solid
And the gas question was that hydrogen chloride dissolves in water to form H+ ions while in methyl benzene it disssolves but doesnt form H+ ions its in the past papers
Original post by bilalmalik283
Guys the exam was easy besides the stupid question on the anomalous result
Im an A* chemistry student at my school if u need answers ask me 00971508955257 whatsapp
Astatine was solid
And the gas question was that hydrogen chloride dissolves in water to form H+ ions while in methyl benzene it disssolves but doesnt form H+ ions its in the past papers


Can you do an unofficial mark scheme?
I have 1pr and 3hr exam in two days i can do it after thursday
Anyone have taken maths edexcel 3HR today?
Original post by ccchiulam
Anyone have taken maths edexcel 3HR today?


me lol rlly tough am expecting 60
Original post by PC.police
me lol rlly tough am expecting 60


What answer did you get for the last Q? I got 48.2 cm
Original post by PC.police
me lol rlly tough am expecting 60


And there is one question about angle in circle with tangent , i got 20degree , how about you @@
Original post by ccchiulam
And there is one question about angle in circle with tangent , i got 20degree , how about you @@


Yes 20 is correct i did it and my teacher told me after the exam its 20
Original post by bilalmalik283
Yes 20 is correct i did it and my teacher told me after the exam its 20


Do you know the similar triangle that one , like express y in terms of x
Original post by bilalmalik283
Yes 20 is correct i did it and my teacher told me after the exam its 20


I got sth like (4x)times(square root 1/65)
Original post by ccchiulam
I got sth like (4x)times(square root 1/65)

Wrong bro answer was the small triangles length square divided by big angle square into x

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