Chemistry: Post your doubts here!

[Zaki ali asghar]

idk man it wasnt THAT easy
i mean many ppl ive asked did find it difficult
even m losing 5 marks already so idk
it should be 60...or 65 max n thaz it

yeah i am glad we aren't discussing it thoroughly lol.

 

[Tauqir_hamed]

Anybody remembers the anode , cathode question.. what were the compounds.. one was conc MgCl2. What were the rest ??

 

[Nushad Nahue]

Does anybody remember the quantitative electrolysis question? What was the answer ?


Also, the NMR and C-13 NMR. How many peaks do you think it had?

 

[Nushad Nahue]

Anybody remembers the anode , cathode question.. what were the compounds.. one was conc MgCl2. What were the rest ??

I think aqueous CuCl2 was one of them.

 

[Tauqir_hamed]

Volume was 448 cm ^3 iirc .
And the products obtained.. were they o2 , cu and cl2 , mg for cucl2 ( aq ) and conc mgcl2 respectively

 

[hamadh]

salaam! could somebody please tell me that when we are drawing graphs of temperature against time or any value like volume of a solution , how are we supposed to draw the line through the points? i mean are we supposed to start from the initial temperature or should we draw the line such that the points are equally distributed on either side?

 

[Hamnah Zahoor]

salaam! could somebody please tell me that when we are drawing graphs of temperature against time or any value like volume of a solution , how are we supposed to draw the line through the points? i mean are we supposed to start from the initial temperature or should we draw the line such that the points are equally distributed on either side?

No it's not necessary to start from initial temperature until the question asks you to do otherwise it should be a best fit line.

 

[Sijanshrestha]

any one has prediction about p33 and p34

if you get please share it

 

[Sijanshrestha]

Prediction for Paper 33 ??

 

[Krypton36]

Any tips for Qualitative Analysis??

 

[Kanekii]

Is the error in measurement of burrete 0.15cm3 or 0.05cm3?

 

[hancy pandey]

Any tips for ion test? Plz help
Prediction too

 

[nitish sah]

any prediction for paper 33 ?????? plzzzz share

 

[Hamnah Zahoor]

Is the error in measurement of burrete 0.15cm3 or 0.05cm3?

+/- 0.05cm3

 

[MARZ132000]

I have 2 questions regarding the chemistry practical:-

1- Do we have to rinse the burette with distilled water and the solution that we are going to use in the burette or will the supervisors do it before the exam?
2- In the enthalpy change experiment, how can we measure the temperature of the solution without taking the thermometer out of the solution and should we stop the stopwatch while measuring the temperature?
It would be also really beneficial if anyone shares any useful website/video regarding the practical.
Answers to these questions will be greatly appreciated.

 

[Hamnah Zahoor]

I have 2 questions regarding the chemistry practical:-

1- Do we have to rinse the burette with distilled water and the solution that we are going to use in the burette or will the supervisors do it before the exam?
2- In the enthalpy change experiment, how can we measure the temperature of the solution without taking the thermometer out of the solution and should we stop the stopwatch while measuring the temperature?
It would be also really beneficial if anyone shares any useful website/video regarding the practical.
Answers to these questions will be greatly appreciated.

1. No it's not necessary to wash it for I believe it would have been done by the supervisors before the exam and also it will waste your time.
2. i think the thermometer is readable enough when inside the solution taking it out will result in outside temperature affecting it and you should not stop the stopwatch while measuring the temperature.

I hope this helps:
https://www.xtremepapers.com/community/threads/tips-for-chemistry-practicals-p3.11810/

 

[Kanekii]

+/- 0.05cm3

But i heard it should +/- 0.15 cm3 as we take readings three times, initial, final and titre is that correct?

 

[PixelsLevls]

But i heard it should +/- 0.15 cm3 as we take readings three times, initial, final and titre is that correct?

The Uncertainty should be half of the smallest reading on your burette. So if the smallest reading is 0.1cm3, you uncertainty will +/- 0.05cm^3
So if you have a uncertainty of 0.15cm^3 then your smallest reading must've been 0.30cm^3! which is very unlikely.
Hope this helped

 

[Kanekii]

The Uncertainty should be half of the smallest reading on your burette. So if the smallest reading is 0.1cm3, you uncertainty will +/- 0.05cm^3
So if you have a uncertainty of 0.15cm^3 then your smallest reading must've been 0.30cm^3! which is very unlikely.
Hope this helped

Yes and thanks

 

[Hamnah Zahoor]

But i heard it should +/- 0.15 cm3 as we take readings three times, initial, final and titre is that correct?

Also you don't take readings three times it's only twice initial and final. Titre is the value you obtain via calculations.