What do you think will come up in Chemistry 32? :)

[Mariam Mohamed SX132]

microscope has alot ov chances!

hahaha its in each year ! i kind of knew that

 

[sara abdul razzaq]

hahahah the mst probable question should be told first

 

[IGCSEstudent2012]

Anytime! Im just scared from bio! I have variant 2 on the 28th

i have the same

 

[IGCSEstudent2012]

And what about the ques in which the student weighed a differnt metal carbonate
we had to show some calculations...

 

[sara abdul razzaq]

And what about the ques in which the student weighed a differnt metal carbonate
we had to show some calculations...

i didnt show any!

 

[aalmuhannadi]

even meeee....... lets hope inshaaAllah it will be one awesome paper!!
u have ny idea about things cumin up in bio ?

Same I got -70 something kJ >.> it's wrong I checked the value of formation of the compound on wikipedia...

 

[aalmuhannadi]

I used E=mct using the both temperatures the student got and another one with the mean temperature, and explained that it's justified because the result is more accurate as it is an average of the two heat changes (and also the enthalpy change would be an average)

 

[sara abdul razzaq]

Same I got -70 something kJ >.> it's wrong I checked the value of formation of the compound on wikipedia...

hmmm i dnt get it where did u get the standard enthalpy of formation from?

 

[sara abdul razzaq]

the reaction was NEUTRALISATION!! we have a similar question october november 2011 ppr 21 u can refer that ............... i think -ve sign is correct!!

 

[sara abdul razzaq]

I used E=mct using the both temperatures the student got and another one with the mean temperature, and explained that it's justified because the result is more accurate as it is an average of the two heat changes (and also the enthalpy change would be an average)

i wrote something similar

 

[Warrior66]

Same I got -70 something kJ >.> it's wrong I checked the value of formation of the compound on wikipedia...

what is the real value for the formation of NaHCO3?

 

[Es Jay]

was the final enthalpy value negative or positive?? i got it negative!

i got -52.9 ..or somewhere around that

 

[HubbaBubba]

I got a negative value, but my original answers for enthalpy change were either way very low :/ 0.0103 KJ and 0.0490 KJ :/ My temperature change wasn't big

 

[aalmuhannadi]

You can

what is the real value for the formation of NaHCO3?

check on Wikipedia it's aroun 900-1000 kj and it's positive not negative

 

[sara abdul razzaq]

i got -52.9 ..or somewhere around that

the values will be different for sure thats obvious caz the temperature n all varies everywhere.........ummm but i hope the final sign negative is correct am not sure about the value .......

 

[Warrior66]

You can
check on Wikipedia it's aroun 900-1000 kj and it's positive not negative

the values will be different for sure thats obvious caz the temperature n all varies everywhere.........ummm but i hope the final sign negative is correct am not sure about the value .......

Well, for one thing, I am pretty sure the final answer was negative not positive. Thermal decomposition is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. Which means that the reaction of Na2CO3 from NaHCO3 is endothermic, meaning that the reverse reaction will be exothermic..
If you recall the reaction from our paper 32, it was 'Na2CO3 + CO2 + H2O = 2NaHCO3' yes? correct me if I am wrong. And we had to make this hess's law thingy which equated 3 reactions.
The question we got was in reverse but exactly the same!

 

[sara abdul razzaq]

Well, for one thing, I am pretty sure the final answer was negative not positive. Thermal decomposition is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. Which means that the reaction of Na2CO3 from NaHCO3 is endothermic, meaning that the reverse reaction will be exothermic..
If you recall the reaction from our paper 32, it was 'Na2CO3 + CO2 + H2O = 2NaHCO3' yes? correct me if I am wrong. And we had to make this hess's law thingy which equated 3 reactions.View attachment 27422
The question we got was in reverse but exactly the same!

hmmmmmmmmmm....alhumdulilah!!!! the sign part freaked me out caz in my batch there was nobody who got NEGATIVE!!! yeayyy!!!!

 

[Warrior66]

^Yes, Alhamdulillahir Rabb Al-Alameen!

 

[aalmuhannadi]

Well, for one thing, I am pretty sure the final answer was negative not positive. Thermal decomposition is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. Which means that the reaction of Na2CO3 from NaHCO3 is endothermic, meaning that the reverse reaction will be exothermic..
If you recall the reaction from our paper 32, it was 'Na2CO3 + CO2 + H2O = 2NaHCO3' yes? correct me if I am wrong. And we had to make this hess's law thingy which equated 3 reactions.View attachment 27422
The question we got was in reverse but exactly the same!

Oh wow thank god! You just saved me a week long of regret my friend haha I thought it was the enthalpy of FORMATION xD that's why I found such a high value on wikipedia D: many thanks

 

[Warrior66]

no problem at all..I was freaking out at first too..Alhamdulillah!