This Page is one of the best academic site I have ever come across. I’ll rate you guys 100 out of 100. I have watched your video on titration and now this… you guys are simply the best
@@medicathron Go and read understanding chemistry by Godwin Ojukuku. Phenolphthalein is used to confirm the presence of CO32- if it's the only anion present in the compound. We are chemist. You don't just say that something is not correct without verifying. You should be humble enough to say, let me confirm and get back to you. Godwin Ojukuku is the chief Examiner of Waec in Nigeria. Try reading his book.
I have only see NECO using phenolphthalein to confirm CO3²-. But we all know it's not absolutely confirming CO3 or perhaps are we saying all substance that change the colour of phenolphthalein contain CO2?@@sesughahowua5745
I love how you broke it down, but residue + dil. Hcl+nh3 in drops wont give a gelatinous ppt. So the observation should just be white ppt formed. Once again thank you sir
I have an issue with when you added HCl to the residue. You are correct with the liberation of CO2. However, since you added HCl to PbCO3 there will also be the the formation of insoluble PbCl2 which dissolves on heating and reappears on cooling To me HNO3 will be used instead of HCl. This is likely to feature in the real exam
Excuse me sir, I thought that they were only two cations that give white gelatinous precipitate i.e Zn and Al Why is Pb also giving the white gelatinous precipitate.
If we think this way, then if we have a chalky precipitate when we use NaOHor NH3 ....then we should have confirmed pb²+ at that stage , and there will be no need to proceed with those questions again
Not a precipitate yet...a chem reaction between water & salt didn't occur... To have precipitate...Chem rxn must occur... Double decomposition/ double displacement/ double dissociation leading to the formation of an insoluble salt "residue" If Na2co3 & pbno32 can react in the solid form....there won't have been any need dissolving it in H20... H20 merely frees the ions , facilitating ion exchange both ways...so that's not a precipitate
Moreso.... a student writing the inference as "precipitate" will simply implicate the student as having a prior knowledge of the salts... when the white paper 📃 is a subject of confidentiality... Norms water 💧 is just solubility test...& the student is supposed to play along "feigning" ignorance of the identity of the exam sample.
You welcome You don't describe a precipitate as "powdery" as you can't feel it with your hand. Also, once a sample is dissolved, it's no longer dry,hence no longer powdery. it's either gelatinous or chalky.
@@extorialmedia check 2008 waec past question 2d(ii) When you have a residue that contains Pb²+ & you add conc HCI.... you get chalky precipitate... For NaOH & NH3....if confused on how to describe the precipitate...simply say white precipitate..Thank you
Yea....at the least chemistry...before chem theory... In the meantime, you can check through other theory lectures on the channel... Plot is to finish this waec&neco sparingly... Then go fully-fledged & all out for utme covering all the topics for utme 2025 starting from August this...that way we can live fully to our name & brand 300plus
Thank you sir Sir how sure are you about the question coming out in this exam so that we'll not study the the table and the see a different thing in the exams.please don't disappoint us
Yes...that's the exact question... Some tweaks coming up...as we also get info... As such next video dropping in 2hours tidy things up.. Take this video & especially the next video on salt analysis seriously.... that's a replica of what your question will be... YOUR QUESTIONS CAN'T GO OUT OF THOSE TWO VIDEOS ON SALT ANALYSIS
Pb²+ was confirmed because with K2Cr2O7 it gives yellow precipitate as seen on display in the video. But with aluminum no precipitate. As a matter of fact, when distinguishing be pb²+ & Al³+...K2Cr2O7 or KI(potassium iodide) is used to confirm pb²+
depends on your question.. if you use NaOH or NH3 ... you are going to get the same result ... in NaOH , both are soluble in excess and give the same white ppt. in NH3, Both are insoluble in excess with the same white white ppt. so There is reason why you will have to use NaOH and then use NH3. He used NH3...but tomorrow you can be given NaOH instead. Best of Luck.!
Well done sir. But you didn't add aqueous NH3 to the 2nd portion of the residue directly, rather, you added it to the solution from 3. Is it right to say 'residue + or solution 3 +... Also, element like Pb and Ca are not gelatinous but chalky, non-gelatinous or powdery.
Yes...that's double displacement reaction for you... Before reaction .. both salts are soluble... After dissolution in water....displacement takes place...leaving one soluble & the other insoluble
The inference supposed to be simply "c is a mixture of two salt" we can't categorical say the solubility of the salts Since the two where mixed and double decomposition is expected to take place.
@@Uncle-Chemical once you observe sample size before adding water & also observe size undissolved in water.... you can tell some of the quantity had dissolved while some did not dissolve . Hence d inference
This Page is one of the best academic site I have ever come across. I’ll rate you guys 100 out of 100. I have watched your video on titration and now this… you guys are simply the best
Feeling elated...
Thanks all the same... all the best in your exam
I love your teachings sir
Glad to hear that
Thank you so very much sir. Y'all are a big help to students, for real. Keep up the good work 🙏💯
Most welcome... & amen...
All the best
Thank you sir
What About alternative to practical sir in physics chemistry and biology
Thanks so much Boss, so glad to have found this 7 hours before my exam😫🤲
Most welcome....brush up....
Success all the way
Thanks 😊 so much Sir
What are the component ions that are present in sample C30 Sir
Thank you sir saw it 2hours before my exams
Same here😂
All the best
Thanks sir
I really understood everything
Do more of physics and biology
Definitely...biology drops this week....we needed to get chem out of the way first
All on the way.... bio drops this week
Try adding phenolphthalein to a solution of the residue. Solution turns pink. Confirmatory test for CO3^2-
Phenolphthalein has no bearing int this exam
@@300plusacademy it might because it is port of the reagents in the instructional material
Phenolphthalein will not confirm CO3²- Mr. it can only tell if it is acidic or not...That's not specific
@@medicathron Go and read understanding chemistry by Godwin Ojukuku. Phenolphthalein is used to confirm the presence of CO32- if it's the only anion present in the compound. We are chemist. You don't just say that something is not correct without verifying. You should be humble enough to say, let me confirm and get back to you. Godwin Ojukuku is the chief Examiner of Waec in Nigeria. Try reading his book.
I have only see NECO using phenolphthalein to confirm CO3²-. But we all know it's not absolutely confirming CO3 or perhaps are we saying all substance that change the colour of phenolphthalein contain CO2?@@sesughahowua5745
This is an eyeopener
Welcome
Thank you so much sir 😁
Most welcome
I love how you broke it down, but residue + dil. Hcl+nh3 in drops wont give a gelatinous ppt.
So the observation should just be white ppt formed.
Once again thank you sir
ua-cam.com/video/LrUD3PtIcfE/v-deo.html
All corrected in the final hints...
Thanks all the same
@@300plusacademy Ok thank you sir
So interesting
Thank you sir but why isnt there a test for sodium to help identify the other inorganic salt(sodium carbonate)?
Cos there's no visible reaction with NaOH & NH3
Thank you so much sir.
You welcome
Thanks
Most welcome
Great job 👍
Thank you
I have an issue with when you added HCl to the residue. You are correct with the liberation of CO2. However, since you added HCl to PbCO3 there will also be the the formation of insoluble PbCl2 which dissolves on heating and reappears on cooling
To me HNO3 will be used instead of HCl.
This is likely to feature in the real exam
I corrected that here in the final hints
See link ua-cam.com/video/LrUD3PtIcfE/v-deo.html
HNO3 was used & I did say ... bin HCl.....
ua-cam.com/video/LrUD3PtIcfE/v-deo.html
Where is the gelatinous precipitate coming from
Addressed that in the video
Was FeSO4 and conc H2SO4 among the reagent?
They are normal lab reagent...
though the conc H2SO4 was just an oversight by waec
Please what about biology
🍳 cooking biology & physics
Physics ohhhhh🙏🏽🙏🏽👐
Sir what if you only put white precipitate instead of white precipitate
You good to go
Good job
Thanks
good
Thanks
This is the same thing know the yellow paper I guess❤. Thank you very much sir.
You welcome
Thank you
You're welcome
Why did I not find this video early enough to this examination.
Now that you found it....make d most of it
Excuse me sir,
I thought that they were only two cations that give white gelatinous precipitate i.e Zn and Al
Why is Pb also giving the white gelatinous precipitate.
If we think this way, then if we have a chalky precipitate when we use NaOHor NH3 ....then we should have confirmed pb²+ at that stage , and there will be no need to proceed with those questions again
If you are confused..I said in the video.... that you simply should just use white precipitate...simple
Sir is it what Is coming out for the weac
Probably, although they are working with what was given to them in the white paper.
Yes...take it seriously
& then the final hints
ua-cam.com/video/LrUD3PtIcfE/v-deo.htmlsi=DZGDuj6-0uXRwWBK
Is that how we would write it in the answer sheet
Yes....
Also take note of the final hints
ua-cam.com/video/LrUD3PtIcfE/v-deo.htmlsi=DZGDuj6-0uXRwWBK
@@300plusacademy yes sir which hint sir
After adding water to the mixture what would be observed is a white precipitate in a solution
Not a precipitate yet...a chem reaction between water & salt didn't occur...
To have precipitate...Chem rxn must occur...
Double decomposition/ double displacement/ double dissociation leading to the formation of an insoluble salt "residue"
If Na2co3 & pbno32 can react in the solid form....there won't have been any need dissolving it in H20...
H20 merely frees the ions , facilitating ion exchange both ways...so that's not a precipitate
Moreso.... a student writing the inference as "precipitate" will simply implicate the student as having a prior knowledge of the salts... when the white paper 📃 is a subject of confidentiality...
Norms water 💧 is just solubility test...& the student is supposed to play along "feigning" ignorance of the identity of the exam sample.
Thank you sir....but i thought lead would give a white powdery precipitate....not white gelatinous precipitate
You welcome
You don't describe a precipitate as "powdery" as you can't feel it with your hand. Also, once a sample is dissolved, it's no longer dry,hence no longer powdery.
it's either gelatinous or chalky.
It's white chalky precipitate sir
@@extorialmedia check 2008 waec past question 2d(ii)
When you have a residue that contains Pb²+ & you add conc HCI.... you get chalky precipitate...
For NaOH & NH3....if confused on how to describe the precipitate...simply say white precipitate..Thank you
You can use chalky or powdery. New school chemistry used powdery.
@@kelechiezeorah4619 okay then 👍
One question though… what does C represents in the first test taken?
C...represent the salt sample you will be given
Sir u are great
But will there be any theory lecture on your platform
Yea....at the least chemistry...before chem theory...
In the meantime, you can check through other theory lectures on the channel...
Plot is to finish this waec&neco sparingly...
Then go fully-fledged & all out for utme covering all the topics for utme 2025 starting from August this...that way we can live fully to our name & brand 300plus
WHAT ABOUT THE REDOX TITRATION SIR?
Yea...the final one on the way...this night
Ok
What about physics practical
Check ✔️ channel
It came out
What does the Cn sample stand for?
That's sample C, n means candidate serial number...say candidate number 128..
Sample on the table will be C128
Thank you sir
Sir how sure are you about the question coming out in this exam so that we'll not study the the table and the see a different thing in the exams.please don't disappoint us
Relax... go for the exam....
at the sight of ur questions...it will be all smiles
Are these the exact questions that are coming out or most of them are coming out not all?
Yes...that's the exact question...
Some tweaks coming up...as we also get info...
As such next video dropping in 2hours tidy things up..
Take this video & especially the next video on salt analysis seriously.... that's a replica of what your question will be...
YOUR QUESTIONS CAN'T GO OUT OF THOSE TWO VIDEOS ON SALT ANALYSIS
Pls is this the exact question
The question is coming In this format & you'll get at least 80% in ur exam
Please why is pb2+confirmed in question 5
Pb²+ was confirmed because with K2Cr2O7 it gives yellow precipitate as seen on display in the video. But with aluminum no precipitate.
As a matter of fact, when distinguishing be pb²+ & Al³+...K2Cr2O7 or KI(potassium iodide) is used to confirm pb²+
Double decomposition or precipitation reaction
Double decomposition ig
Please is this the exact question for 2024
Your question will be like this 80% at the least....take it seriously
Thank you sir ❤
Most welcome
You didn't use NaOH to test for d cation
depends on your question.. if you use NaOH or NH3 ... you are going to get the same result ... in NaOH , both are soluble in excess and give the same white ppt. in NH3, Both are insoluble in excess with the same white white ppt. so There is reason why you will have to use NaOH and then use NH3. He used NH3...but tomorrow you can be given NaOH instead. Best of Luck.!
Sir, why is calcium ion not suspected
Ca²± is not part of the salt this year
@@300plusacademy okay sir. But what of Aluminum
Calcium ion is a dirty ppt
Ca doesn't give a visible reaction with NH3... you can't suspect Ca.
Please is lead soluble in water
Depending on the lead...pbcl2 not soluble,
Pbco3 not soluble...pb(no3)2 soluble...
Thank you sir
You welcome
👍👍👍
Welcome
Please has WAEC released calculator for this year's exam?
Should be released on or before Thursday...
That's their standard practice
Well done sir.
But you didn't add aqueous NH3 to the 2nd portion of the residue directly, rather, you added it to the solution from 3. Is it right to say 'residue + or solution 3 +... Also, element like Pb and Ca are not gelatinous but chalky, non-gelatinous or powdery.
That's why it's recorded on the board as "residue +HCl"
saying solution in (3) is also correct
❤❤❤❤
Thank you
It ought to be Residue + dil HNO3 not dil HCl
THANKS man... a video production 99%done in the offing to bring clarity on that
Is this the exact practical we'll be seen
Yes....don't be caught napping
Is this really the question
Study it....that's a replica of what you'll see tomorrow
@@300plusacademy sorry but I'm in alternative b will the question be the same
Sir is this a predicted question
That's what you'll have >80% guaranteed
@@300plusacademythank you sir
Good job 👍👏, but residue +BaCl2 form white ppt of SO4,CO3 SO3 , then it's Dil HCl acid that confirms CO2
Yea...a final correction coming on all the identified gray areas....thank you
U can't use dil HCl but HNO3 because Pb will react with Cl from Hcl
Thank you sire
You welcome
Hmm! Soluble and insiluble salts but the two salts are soluble
Yes...that's double displacement reaction for you...
Before reaction .. both salts are soluble...
After dissolution in water....displacement takes place...leaving one soluble & the other insoluble
The inference supposed to be simply "c is a mixture of two salt" we can't categorical say the solubility of the salts Since the two where mixed and double decomposition is expected to take place.
@@Uncle-Chemical once you observe sample size before adding water & also observe size undissolved in water.... you can tell some of the quantity had dissolved while some did not dissolve . Hence d inference
@@Uncle-Chemical saying mixture of two salts ... too is correct
You will be given the two salts in mixed form.
So when you add water they will be partially soluble.
Just follow exactly what you are asked to do.
❤
I love this
Glad you did
i just find it😂😂😂
What did u ginger 😉
Good job
Thanks
i just find it😂😂😂
Nice job