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Edexcel IAL Chemistry Unit 01 - 26th of May, 2017

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Can someone explain why there is an increase in the temperature here even though the reaction is endothermic? And I basically don't understand the shape of the graph at all...


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Original post by Droneon
ImageUploadedByStudent Room1494096323.620096.jpg

Can someone explain why there is an increase in the temperature here even though the reaction is endothermic? And I basically don't understand the shape of the graph at all...


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That paper is May 2015 unit 3. Well I just realized I'm supposed to post this in the unit 3 thread XD


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Original post by Droneon
ImageUploadedByStudent Room1494096323.620096.jpg

Can someone explain why there is an increase in the temperature here even though the reaction is endothermic? And I basically don't understand the shape of the graph at all...


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The reaction is endothermic, so the reaction mixture cools quickly at the start to drop below room temperature. Then after the reaction is over, the temperature of the product mixture will rise back up as heat energy from the room is transferred to it. Leave it for long enough, and the solution will reach room temperature again.

It's like leaving a cube of ice in a room: it will melt, and its water will heat to room temperature because air molecules that collide with the liquid molecules will transfer some of their kinetic energy to the liquid molecules, and thus heat up the liquid.
Original post by K-Man_PhysCheM
The reaction is endothermic, so the reaction mixture cools quickly at the start to drop below room temperature. Then after the reaction is over, the temperature of the product mixture will rise back up as heat energy from the room is transferred to it. Leave it for long enough, and the solution will reach room temperature again.

It's like leaving a cube of ice in a room: it will melt, and its water will heat to room temperature because air molecules that collide with the liquid molecules will transfer some of their kinetic energy to the liquid molecules, and thus heat up the liquid.


But it would never return to the temperature of the initial reaction mixture right?


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Original post by Droneon
But it would never return to the temperature of the initial reaction mixture right?


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The first solution in the beaker is initially at room temperature. At the moment of adding the second reactant, the temperature drops until the reaction has finished. The temperature difference between the air and the liquid will cause the mixture's temperature to then increase over time. This continues until there is no temperature difference, ie until the liquid mixture in the beaker reaches room temperature again. This would probably take longer than the time on the graph, hence the graph does not show it reaching initial temperature yet.
Original post by K-Man_PhysCheM
The first solution in the beaker is initially at room temperature. At the moment of adding the second reactant, the temperature drops until the reaction has finished. The temperature difference between the air and the liquid will cause the mixture's temperature to then increase over time. This continues until there is no temperature difference, ie until the liquid mixture in the beaker reaches room temperature again. This would probably take longer than the time on the graph, hence the graph does not show it reaching initial temperature yet.


That totally helped, thank you so much!! :smile:


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Original post by Reshyna
First of all, I was doing a past paper and I came up with a doubt.
This is the question.
doubt MCQ.png
Why is the answer A instead of B. Why can't B be the answer?


george facer page 202 explains it and in
ann fullick AS chemistry page 187
Original post by Reshyna
If a carbon-carbon single bond is known as sigma bond, and a carbon-carbon double bond consists of a sigma bond and a pi bond, then what about carbon-carbon triple bond?
What bonds does it contain?


i checked the books and there was nothing on triple bonds and their respective pi and sigma bonds
it isnt required by our specification
Original post by azrah vakil
george facer page 202 explains it and in
ann fullick AS chemistry page 187



If you can please send me a link to where I can get a pdf for the George facer book
Original post by Crystal_M
If you can please send me a link to where I can get a pdf for the George facer book


do u have an ebook account because there's one link that requires ur ebook account

and i only found a revision guide of the george facer book https://www.hoddereducation.co.uk/media/Documents/Science/A-Level-Chemistry_Edexcel_FACER__Sample-Chapter.pdf
Reply 31
Avatar for Reshyna
Reshyna
OP
15
Is everyone ready for the exam? :smile:
How are preparations going on guys?
(edited 6 years ago)
Original post by Reshyna
Is everyone ready for the exam? :smile:
How are preparations going on guys?


havent started yet.. i can only focus on this after C12 exam tomorrow
Original post by zooshan
havent started yet.. i can only focus on this after C12 exam tomorrow


Hey is there a C12 thread


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Original post by Droneon
Hey is there a C12 thread


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i havent found one.. are u doing c12 then?
Original post by zooshan
i havent found one.. are u doing c12 then?


Yes I am. :smile: How's the prep going? I've done only a few papers and I'm trying to keep the concepts in my head until the exam at least lol am I the only one who has been focusing a lot on the other subs besides math lol?


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Original post by Droneon
Yes I am. :smile: How's the prep going? I've done only a few papers and I'm trying to keep the concepts in my head until the exam at least lol am I the only one who has been focusing a lot on the other subs besides math lol?


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ohh.. finally someone who is doing c12..
i have done the papers.. my teacher asked to do jan 16 june 10 and jan 17
i just keep making elementary stupid mistakes...
not only u.. studying four subjects is hard.. and then there is c34 :/
Original post by zooshan
ohh.. finally someone who is doing c12..
i have done the papers.. my teacher asked to do jan 16 june 10 and jan 17
i just keep making elementary stupid mistakes...
not only u.. studying four subjects is hard.. and then there is c34 :/


I keep doing the same thing! :/ Oh so you're doing A2 maths as well? Wow I can't imagine how tough that might be. Yeah I'm taking four too...


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Original post by Droneon
I keep doing the same thing! :/ Oh so you're doing A2 maths as well? Wow I can't imagine how tough that might be. Yeah I'm taking four too...


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ohh u must AS level then.. yeah its hard.. and i have chem the day after.. sigh..
just hope its a moderate paper,.. i feel too drained to do anymore questions tonight.. hbu?
Original post by zooshan
ohh u must AS level then.. yeah its hard.. and i have chem the day after.. sigh..
just hope its a moderate paper,.. i feel too drained to do anymore questions tonight.. hbu?


Hoping the same honestly. Yeah I am. I have bio the day after and then Chem on Friday.
I am so done rn, I'm trying to solve a logarithm ques rn and I just can't concentrate.


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