How was chem p34

[Topperman]

Guys I'm freaking out.. At my centre everyone including the teacher got the titre value around 7.00 cm3...!! How will that affect the marks?!

 

[muhammadali233]

Guys I'm freaking out.. At my centre everyone including the teacher got the titre value around 7.00 cm3...!! How will that affect the marks?!

I am not a chem guy but that 7 cm3 is wrong,i have taken many practical but never got 7 as my reading ,you usually get 22 to 27 reading what were your reading if it is around 23-27 it might be correct but don't worry mine were also wrong it is 3 or 4 marks chill nig

 

[sarmad zubair]

hey guys you wont believe but almost all of my friends got titre volume less than 10 and i got around 12.8... how is that possible??? i mean how so many candidates do the same mistake. And if we are wrong then how much marks we will lose??? And in test of ions was ammonia gas released, i smelled it! its smell is ugh! Please help help help!!! please share ur salt analysis tests.

 

[hassannouman]

Wat were the ions in the last question??

Q.3) Salt Analysis

• Cation in FB4 = Manganese (II)
• Anion in FB4 = Chloride
• Suggested cations in FB5 = Magnesium or Aluminium
• Suggested anions in FB5 = Sulfate or Sulfite
• Cation in FB5 = Magnesium (II)
• Cations in FB6 = Ammonium and Iron (III)

 

[hassannouman]

Guys I'm freaking out.. At my centre everyone including the teacher got the titre value around 7.00 cm3...!! How will that affect the marks?!

hey guys you wont believe but almost all of my friends got titre volume less than 10 and i got around 12.8... how is that possible??? i mean how so many candidates do the same mistake. And if we are wrong then how much marks we will lose??? And in test of ions was ammonia gas released, i smelled it! its smell is ugh! Please help help help!!! please share ur salt analysis tests.

You may lose 3-4 marks, how the titre value is too low? with HCl (FB2) in burette, 25 cm3 Ammonia in conical flask with 3 drops of methyl orange, the value was 7-12 cm3?
Q.3) Salt Analysis

• Cation in FB4 = Manganese (II)
• Anion in FB4 = Chloride
• Suggested cations in FB5 = Magnesium or Aluminium
• Suggested anions in FB5 = Sulfate or Sulfite
• Cation in FB5 = Magnesium (II)
• Cations in FB6 = Ammonium and Iron (III)

Examiner didn't ask to test for gas

 

[Amandaissocoollike]

Okay, so suppose I got the one of the observations of FB4 and FB5 mixed up (where we got the result for Chloride), will i get ecf marks for writing Chloride with FB5 instead?

 

[hassannouman]

Okay, so suppose I got the one of the observations of FB4 and FB5 mixed up (where we got the result for Chloride), will i get ecf marks for writing Chloride with FB5 instead?

I don't think so as observation would be wrong so writing Chloride in FB5 will be incorrect

 

[M.Fazy]

Q.1) Titration

• At my centre, supervisor's titre value = 26.00 cm3
• My mean titre value (Volume of FB2 used) = 26.25 cm3

Q.2) Enthalpy change

• Temperature fall in 1st experiment = 8.0 °C
• Temperature fall in 2nd experiment = 13.0 °C
• Mean temperature fall = 10.5 °C
• Enthalpy change of solution = +14.7 kJ/mol
• 1st Experiment had greater % error because smaller mass was used.
• % error = 6.25%

Q.3) Salt Analysis

• Cation in FB4 = Manganese (II)
• Anion in FB4 = Chloride
• Suggested cations in FB5 = Magnesium or Aluminium
• Suggested anions in FB5 = Sulfate or Sulfite
• Cation in FB5 = Magnesium (II)
• Cations in FB6 = Ammonium and Iron (III)

Almost spot on.

Didn't asked for titre value from my supervisor but I had got 22.03.

Just didn't wrote NH4 in FB6 instead wrote SO4 lol. Gonna loose 3-4 for accuracy overall and 3 surely for 3 (1marks) questions I didn't attempted. Other then that, all good.

 

[hassannouman]

Almost spot on.

Didn't asked for titre value from my supervisor but I had got 22.03.

Just didn't wrote NH4 in FB6 instead wrote SO4 lol. Gonna loose 3-4 for accuracy overall and 3 surely for 3 (1marks) questions I didn't attempted. Other then that, all good.

The anion present in FB6 was SO4^2- , examiner asked the two cations in FB6

 

[Abdul Hanan]

i made a silly mistake guys...
the second table asked for a reagent for identifying "cation"
i don't know what happened and i just identified b/w sulfate and sulfite by using HCL and observe if gas produced no gas produced and i wrote "sulfate"
all 3 marks gone or will it be ecf for considering wrong ions?
thanks

 

[shafkathussain]

How did you calculate the percentage difference between the concentrations in the first question?

 

[lesnar8]

The anion present in FB6 was SO4^2- , examiner asked the two cations in FB6

They asked for 2 anions na? so you had to say so4 and so3 (if you missed one, you'll lose 1 mark I guess)

 

[hassannouman]

i made a silly mistake guys...
the second table asked for a reagent for identifying "cation"
i don't know what happened and i just identified b/w sulfate and sulfite by using HCL and observe if gas produced no gas produced and i wrote "sulfate"
all 3 marks gone or will it be ecf for considering wrong ions?
thanks

The reagent was NaOH (aq) , oh how can you mess up cation with anion? very silly mistake :/

 

[hassannouman]

How did you calculate the percentage difference between the concentrations in the first question?

The correct method of calculating % difference = Percentage difference equals the absolute value of the change in value (difference between 2 values), divided by the average of the 2 numbers, all multiplied by 100. In that part 2 numbers were 15 and 9.35 or your calculated conc., I calculated 38% (using 9.35) which I think is wrong according to above formula. It should be 5.65/12.175 X 100 = 46%

 

[hassannouman]

They asked for 2 anions na? so you had to say so4 and so3 (if you missed one, you'll lose 1 mark I guess)

Suggested anions in FB 5 were asked which were SO4 and SO3 and in FB 6, two cations were asked which were NH4 and Fe3+

 

[bakhita]

Q.1) Titration

• At my centre, supervisor's titre value = 26.00 cm3
• My mean titre value (Volume of FB2 used) = 26.25 cm3

Q.2) Enthalpy change

• Temperature fall in 1st experiment = 8.0 °C
• Temperature fall in 2nd experiment = 13.0 °C
• Mean temperature fall = 10.5 °C
• Enthalpy change of solution = +14.7 kJ/mol
• 1st Experiment had greater % error because smaller mass was used.
• % error = 6.25%

Q.3) Salt Analysis

• Cation in FB4 = Manganese (II)
• Anion in FB4 = Chloride
• Suggested cations in FB5 = Magnesium or Aluminium
• Suggested anions in FB5 = Sulfate or Sulfite
• Cation in FB5 = Magnesium (II)
• Cations in FB6 = Ammonium and Iron (III)

by supervisor, do you mean invigilator? Do the invigilator tell you the titre, Please explain it. I'll be appearing first time so it's very confusing for mem. Please reply

 

[Abdul Hanan]

by supervisor, do you mean invigilator? Do the invigilator tell you the titre, Please explain it. I'll be appearing first time so it's very confusing for mem. Please reply

if your supervisor is a friendly person and not following rules.
my supervisor of chemistry told me almost every single answer of the practical exam, after exam.
And no supervisor is not an invigilator but a person (good teacher) who performs the practical exam with the apparatus that is provided to you and sends his results to CIE.
If your results are not around the values of the supervisor than you loose marks enough to lower your grade. Around 5 in chemistry are a lot of marks.

 

[hassannouman]

by supervisor, do you mean invigilator? Do the invigilator tell you the titre, Please explain it. I'll be appearing first time so it's very confusing for mem. Please reply

Abdul Hanan is right, Supervisor is not an invigilator , supervisor is the one who perform the experiment before exam and get all the readings. Our values should be very close to supervisor's values.

 

[Quizzical Nuts]

It was soo hard. :'( I'm losing soo many marks.