[Paper Analysis] 2023 O-Level Chem Practical | 6092/P3

[@memeborder277]

Thanks for the analysis Mr Ng, I carelessly forgot about the 1 cm^3 of acid included in the reaction 😂 but it's all good right lose Abit of marks only

[@combustiblefire5510]

Meanwhile i got a loss of 1.7g (after adding the 0.7g of mineral) and ended up woth 684% by mass

[@Chinope_EN]

10:00 Do I get ecf 2m for c)ii) ? I get part i) wrong but I use that ans divided by 5 for part ii)

[@ginnuanthony9169]

same i also divide by 5 i not sure, its a 2 mark question also

[@hyxzsn]

thank you mr ng , really needed this , found out that i had a few mistakes but all is good. 👍🏻

[@pugalvannanmuruganandham7624]

One more question, for the planning I put the round bottom flack in a water bath, cause I thought that these liquids are flammable and may catch fire

[@FortniteGorilla-x4f]

So do we need to describe the Carbon dioxide test for both experiments 1 and 2? So for the first mark(in exp 1) u need to describe colour change+ describe CO2 gas test isit? And for uncertainty do we have to include the +_ in front of the 2.0?

[@novastraightd1675]

Steady lah mr ng 💪💪💪💪🤙🤙🔥🔥🔥🔥

[@ginnuanthony9169]

do we draw a best fit line with the anomalie or without them

[@praseedachowdary]

11:36 can write that water is added to dilute B to have different concentrations of B?

[@ginnuanthony9169]

sadly must say to keep total volume of b constant

[@vicchua39]

For question 2, the solid contains CuCl2. So for test 1, will it decompose to form Cl2 gas and do we have to test for it?

[@burnd7426]

Hi Isit supposed to be +-2.0 . And for planning if I write simple distlliation but also state to remove the beaker after temperature exceeds 49 degrees will I get some marks?

[@ginnuanthony9169]

im not sure because it is mixture

[@litang4655]

i kinda changed my results for percentage loss qns bcoz I thot getting percentage gain is wrong. I will still get ecf right??

[@chemfanatic]

is there ecf for the rest of the questions if my mass of co2 is wrong?

[@ginnuanthony9169]

i think so

[@uhok4898]

Yes got ecf! Don't worry abt it (: everyone's mass differs!! 😃

[@pugalvannanmuruganandham7624]

My teacher said that, for that question there will be a wide range of acceptable answers as even the teacher who did the experiment during the 4 shifts got different answers

[@pugalvannanmuruganandham7624]

One of my friend got 16% and the other got 77%

[@pugalvannanmuruganandham7624]

Hi how many marks will be loss if we drew a curve, cause I drew an exponential curve( I had like nil anomaly). Will there be ecf for the description of the graph?

[@pugalvannanmuruganandham7624]

Cause some of my teachers said that, even if you draw a curve, they will still mark you right and I am basing my graph of the data I have collected. But other teachers say that I will be penalised for it

[@yeetymusprimus2225]

5:45 many of my teachers said it was meant to be a curve. They said draw a best fit line and a line can also be a curved line. This is speed of reaction so the graph should be a curve isn’t it???

[@BernardNg]

It is a straight line. I am 101% sure. :)

[@yeetymusprimus2225]

Hope fully, I drew a straight line 🙏🙏🙏🙏@@BernardNg

[@pugalvannanmuruganandham7624]

I drew a curve, like 90% of the student in my school drew a straight line but me and some others drew a curve 😭

[@yeetymusprimus2225]

@@pugalvannanmuruganandham7624 mine got 50-50

[@zhengyang9293]

I used conical flask for the fractional distillation 😢

[@Xxx1124xxx]

Same omg 😭😭

[@uhok4898]

hii! For the last qn i wrote potassium manganate, would it be accepted? i mean its a carboxylic acid anyway right? Ans also, if i forgot the fractionatint column for the fractional distillation how many marks wld i be penalised?

[@pugalvannanmuruganandham7624]

The it will be called simple distillation, for which you will still get the full marks 😊

[@Chinope_EN]

I don't think KMnO4 is acceptable since there's propanol in the solution also (as stated in the qn paper), so it'll just turn purple to colourless) -> [The presence of propanol and propanoic acid in the solution]

[@SamiChenVA]

wah it's over alr

[@yeolmin924]

hi Mr Ng! i screwed up for the planning qn and blanked out… i wrote a really strange method that involved heating the mixture until 49 degrees and condensing the gas in a condenser… but with no mention of fractional distillation. will i still be able to get at least 1 mark?

[@pugalvannanmuruganandham7624]

Probably 1-2 m

[@AfeefHussain]

Uhmm sir what if i did distillation only. Would I not get any marks at all.

[@chemfanatic]

hi for the last question when you are supposed to test for the acid i put alcohol to produce a sweet smelling liquid which is an ester, is this answer accepted?

[@BernardNg]

Recall esterification also requires the addition of conc. sulfuric acid as catalyst and heating to form the ester. This is too elaborate for a chemical test so unfortunately I don't think it will be accepted.

[@pugalvannanmuruganandham7624]

Hi teacher, for the question on why we add water to the solution of b, this was roughly my answer ( can you help me check if it is ok) “ it is to ensure that the concentration of B varies, and to ensure that the total volume of B used is constant for different concentrations”

[@ginnuanthony9169]

your first line is what i wrote only, u wrote the second line also so i think u would get the mark

[@burnd7426]

Will I get correct if I got 0.13g of CO2

[@applejuice250]

yepp dw abt the mass, it differs for everyone. worst case u lose 1m and ecf the rest to get correct

[@jjj07]

I have a question. For question 1, the mole ratio of sodium thiosulphate to HCl is 1:2. However, using the formula you provided, it is assumed that both of the reactants have the same moles. Is that the case?

[@YESNCN]

i have the same question i did stoichiometry yet my ans is wrong🥲

[@nubofmaster]

theoretically the graph should be a straight line, but if the plots are similar in the way of an exponential curve, will it be accepted to draw a best fine curve?

[@pugalvannanmuruganandham7624]

Ya mine too

[@pugalvannanmuruganandham7624]

I also got and exponential curve, wait so will they minus marks for the graph explanation 😭

[@BernardNg]

Actually it is possible to have an exponential curve for such plots. You will learn in higher levels that for some reactions, the rate may be second order with respect to a reactant, then the plot will be exponential.

[@BernardNg]

But for this reaction, it is well-established that rate is first-order with respect to sodium thiosulfate, so the plot should be a straight line.

[@pugalvannanmuruganandham7624]

How many marks with we loss

[@Uhmmhmhgdnjdhij]

As long as fractional distillation was suggested its at least 1m right

[@Chinope_EN]

If u r able to draw it out then it's 1m, so unless u draw out then u need to describe the process of fractional distillation

[@RaghuSriramBowenss]

If we extrapolate after drawing curve will we still get the mark? Thank you for the useful video!!!

[@pugalvannanmuruganandham7624]

Ya

[@veryvelestial]

I have a question! For the last part, is Magnesium ribbon accepted to test for propanoic acid? Because even if there's no acid, won't the metal react with water to produce a metal hydroxide + H2 gas, so testing for H2 gas won't matter because H2 is produced with or without acid?? HELP PLS!!

[@BernardNg]

Yes. Using Mg ribbon will still be correct due to the context of the question. Since we are testing for the presence of propanoic acid in liquid propanal, we can assume that there is negligible water present.

[@BernardNg]

However I don't think the qns is asking for the test for hydrogen gas. Simply the observation of bubbles/ effervescence.

[@veryvelestial]

@@BernardNgYah, so the answer would be: "Add metal. If propanoic acid is present, effervescence of colourless odourless gas produced..." then describe test for h2 gas

[@pugalvannanmuruganandham7624]

I added CaCO3, then observed for effervescence, then to bubble the gas into lime water

[@mary-zv1zm]

hi how many marks would be deducted if i drew a curve instead of a straight line?

[@Chinope_EN]

If the shape of the graph is wrong, then deduct 1m

[@wonn_saturu]

After fractional distillation, I wrote crystalisaiton to get propanol crystals , how much marks will I be deducted😅

[@clent444]

for the uncertainty question , can put plus minus 2? 😅

[@BernardNg]

As in plus minus 2.0%? Should be alright

[@clent444]

@@BernardNg yea plus minus 2.0 :D

[@YESNCN]

Hi why can’t the planning be simple distillation?

[@BernardNg]

Simple distillation should work just that the purity of propanal will not be as high. Nonetheless, for a mixture containing more than 2 liquids, we should choose fractional over simple distillation

[@YESNCN]

@@BernardNgi see thank you! But will i still get the marks if i wrote simple distillation?

[@8348beab]

My friend tested for hydrogen and burned a hole through her paper 😱

[@BernardNg]

😲 she submitted a holy script!! 😏

[@zx5298]

was i supposed to know school got condenser for distillation

[@pugalvannanmuruganandham7624]

Ya

[@pugalvannanmuruganandham7624]

My friend drew the industrial fractional distinction diagram, the one used to separate crude oil

[@BernardNg]

Erm.. have. All the apparatus we learn in chapter 1 can be found in the school laboratory.