CHEMISTRY PAPER 3 DOUBTSS!!

[amina1300]

--> Place a small spatula measure of FB 5 in a boiling tube, add a 1cm depth of dilute hydrochloric acid and warm the contents of the tube gently.
Observation : FB 5 + HCl: effervescence/ fizzing/ bubbling gas pops with lighted splint

-->Place small spatula measures of FB 5 and FB 6 in a single boiling tube. Use a test-tube holder to hold the tube. Add a 2cm depth of aqueous sodium hydroxide. CARE
Observation: FB 5 + FB 6 + NaOH: vigorous / violent/ exothermic / great/ extreme/ lots of and effervescence/ fizzing/ bubbling gas/NH3 turns (damp) red litmus (paper) blue.

How do we identify FB 5 is???

Fb5 is Al or Zn (s)
Is there a logical way to deduce this???

--> "Al and Zn reduce NO3- to ammonia in basic solutions"?

I searched, found out that this reaction is called "a nitrate test using Devarda's alloy", but there is no specific description of the process in our syllabus so how do the examiners expect us to know this!!

 

[Roe Mir]

Which year is this?

 

[anastasia grey113]

--> Place a small spatula measure of FB 5 in a boiling tube, add a 1cm depth of dilute hydrochloric acid and warm the contents of the tube gently.
Observation : FB 5 + HCl: effervescence/ fizzing/ bubbling gas pops with lighted splint

-->Place small spatula measures of FB 5 and FB 6 in a single boiling tube. Use a test-tube holder to hold the tube. Add a 2cm depth of aqueous sodium hydroxide. CARE
Observation: FB 5 + FB 6 + NaOH: vigorous / violent/ exothermic / great/ extreme/ lots of and effervescence/ fizzing/ bubbling gas/NH3 turns (damp) red litmus (paper) blue.

How do we identify FB 5 is???

Fb5 is Al or Zn (s)
Is there a logical way to deduce this???

--> "Al and Zn reduce NO3- to ammonia in basic solutions"?

I searched, found out that this reaction is called "a nitrate test using Devarda's alloy", but there is no specific description of the process in our syllabus so how do the examiners expect us to know this!!

it may be an old paper

 

[amina1300]

it may be an old paper

Dude its 2016
https://papers.gceguide.xyz/A Levels/Chemistry (9701)/9701_s16_qp_32.pdf

 

[amina1300]

Which year is this?

s2016 qp 32

 

[anastasia grey113]

s2016 qp 32

thats a different zone amina
syllabus may vary who knows
v have 33 n 34 here

 

[Zaki ali asghar]

who else is giving 33 on 23rd may

 

[Roe Mir]

I am

 

[Zaki ali asghar]

https://papers.gceguide.com/A Levels/Chemistry (9701)/9701_s16_qp_34.pdf can anyone help me in ci part i am not sure how to deal with dilution factor,i took my titre as 24.10 cm^3 can someone help me with finding no of moles in ci

 

[anastasia grey113]

who else is giving 33 on 23rd may

meee

 

[Zaki ali asghar]

meee

can you help with finding moles for the paper and part i posted please.

 

[amina1300]

thats a different zone amina
syllabus may vary who knows
v have 33 n 34 here

I hope thats the case.

 

[Zaki ali asghar]

I hope thats the case.

hey any predictions for chemistry 33

 

[amina1300]

hey any predictions for chemistry 33

No luck this time.

 

[anastasia grey113]

can you help with finding moles for the paper and part i posted please.

use a volume of 10
like this
10 x conc of HCl in FB2/1000
to find total moles

then
moles x ur volume/250

i think thats how it works
ill let u know confirmed by tonight

 

[Zaki ali asghar]

in ms it is stated that 0.008*vol/1000,the answer differs by a power of 10

 

[anastasia grey113]

in ms it is stated that 0.008*vol/1000,the answer differs by a power of 10

u sure?
m getting 0.00008 instead of 0.008 :/

 

[Zaki ali asghar]

https://papers.gceguide.com/A Levels/Chemistry (9701)/9701_s16_ms_34.pdf

 

[Zaki ali asghar]

i think markscheme is probably wrong here,i did it using both methods to calculate the value of x,using the no of moles found using ur method the answer for x came as 6 which should be acceptable while with ms method the answer was very high like 300 which is wrong.

 

[anastasia grey113]

i think markscheme is probably wrong here,i did it using both methods to calculate the value of x,using the no of moles found using ur method the answer for x came as 6 which should be acceptable while with ms method the answer was very high like 300 which is wrong.

its 0.08
u r right increased by a power of 10
ms must be wrong