<![CDATA[O-Level Chemistry]]>Hi, my elder boy ran into an issue with the following.


Hope someone can enlighten him. Many thanks in advance.
******************************************************

We need to calculate the enthalpy change of a certain reaction, usually acid-base, acid-carbonate, or dissolution reactions. So we take the two substances and mix them together and record the temperature change. Using Q=mcT, we calculate the amount of thermal energy given off or taken in by the reaction, and then using H=Q/n we find the enthalpy change of the reaction. However, the confusion is what value of n (number of moles) to use.

Examples of reactions:

HCl + NaOH -> H20 + NaCl (here n is the mol of any one of the reactants or products, no confusion.)

2HNO3 + Na2CO3 -> H2O + 2NaNO3 (here teacher says take mol of H2O, because it is the one carrying off the thermal energy. Or take it as the mol of Na2CO3, because that is the reactant that is changing, not the acid.)

H2SO4 + KOH -> 2H2O + K2SO4 (here following the same rule as above, taking the number of mol of water, is for some reason wrong.)

Is there a general rule or concept that allows you to figure out exactly which number of mol to use?

]]>https://forum.kiasuparents.com/topic/73327/o-level-chemistryRSS for NodeSat, 18 Apr 2026 19:05:47 GMTWed, 27 Mar 2013 13:54:58 GMT60<![CDATA[Reply to O-Level Chemistry on Sun, 07 Sep 2025 16:07:02 GMT]]>Predictions to GCE O Level Science (Chem) 2025 paper :https://youtu.be/f9QqxgRMquM?si=fbKmKh3WaFl2KEn8

]]>https://forum.kiasuparents.com/post/2146087https://forum.kiasuparents.com/post/2146087Sun, 07 Sep 2025 16:07:02 GMT<![CDATA[Reply to O-Level Chemistry on Sun, 31 Aug 2025 11:36:37 GMT]]>Prediction to 2025 O Level Chemistry (Bold prediction)

https://youtu.be/P0lP_BedWFA?si=6gJ8xDS8J98j6JVe

]]>https://forum.kiasuparents.com/post/2146025https://forum.kiasuparents.com/post/2146025Sun, 31 Aug 2025 11:36:37 GMT<![CDATA[Reply to O-Level Chemistry on Tue, 22 Oct 2024 16:25:15 GMT]]>https://youtu.be/DMhdOi4IaW4?si=bsBS412DaOFADEd4

Tips and strategies for Combined O Level Science Paper 2024

]]>https://forum.kiasuparents.com/post/2142152https://forum.kiasuparents.com/post/2142152Tue, 22 Oct 2024 16:25:15 GMT<![CDATA[Reply to O-Level Chemistry on Thu, 17 Oct 2024 06:27:04 GMT]]>For those taking O Level Chemistry this year, here are the tips:

https://youtu.be/12yPZDG-DjQ?si=mvqyLP0SdfT0YtaQ

]]>https://forum.kiasuparents.com/post/2142131https://forum.kiasuparents.com/post/2142131Thu, 17 Oct 2024 06:27:04 GMT<![CDATA[Reply to O-Level Chemistry on Thu, 19 Sep 2024 14:42:03 GMT]]>Hi all

For those taking Sec 3 Chemistry Exam soon, here are some tips.

https://youtu.be/Cq2NyQknfdA?si=qhlkrpm9DnvdbUeJ

]]>https://forum.kiasuparents.com/post/2141708https://forum.kiasuparents.com/post/2141708Thu, 19 Sep 2024 14:42:03 GMT<![CDATA[Reply to O-Level Chemistry on Wed, 31 Jul 2024 05:51:38 GMT]]>@0limshs hi I’ve one to recommend. I engaged this math tutor and she has a science tutor working under her. We have also engaged the science tutor since the start of last year for my 2 kids. You may contact the tutor via WhatsApp at 83443012

Wish you all the best!

]]>https://forum.kiasuparents.com/post/2136669https://forum.kiasuparents.com/post/2136669Wed, 31 Jul 2024 05:51:38 GMT<![CDATA[Reply to O-Level Chemistry on Mon, 29 Jul 2024 18:35:08 GMT]]>@0limshs hello, have you found one ? Otherwise I can recommend. You can PM me.

]]>https://forum.kiasuparents.com/post/2136594https://forum.kiasuparents.com/post/2136594Mon, 29 Jul 2024 18:35:08 GMT<![CDATA[Reply to O-Level Chemistry on Wed, 12 Jun 2024 07:05:57 GMT]]>I am sharing a video on tips to study GCE O Level Science (Chemistry) 2024.

Hope this is helpful.

https://youtu.be/9Bub8T5fTIg?si=1temV_aZlT_Bxtx5

]]>https://forum.kiasuparents.com/post/2134977https://forum.kiasuparents.com/post/2134977Wed, 12 Jun 2024 07:05:57 GMT<![CDATA[Reply to O-Level Chemistry on Wed, 15 May 2024 10:13:12 GMT]]>Dear all


The predictions to this year GCE O Level 6092 - 2024 Paper.

https://youtu.be/P0PaUY66z3I?si=Ue-ewqmzXW0ZAedx

I think this prediction is accurate.

]]>https://forum.kiasuparents.com/post/2133907https://forum.kiasuparents.com/post/2133907Wed, 15 May 2024 10:13:12 GMT<![CDATA[Reply to O-Level Chemistry on Fri, 10 May 2024 00:26:48 GMT]]>Hi parents, I’m looking for Biology and Chemistry tutor for sec 3, at West area. Please let me know if you have any good recommendation.

]]>https://forum.kiasuparents.com/post/2133673https://forum.kiasuparents.com/post/2133673Fri, 10 May 2024 00:26:48 GMT<![CDATA[Reply to O-Level Chemistry on Fri, 13 Oct 2023 00:56:17 GMT]]>here is


2023 O-level Chemistry 6092
Paper 3 Practical exam question,
came out on last Wednesday (4 October 2023), on

sodium thiosulphate and rate (speed) of reaction :-

https://www.youtube.com/watch?v=A37-vJ52OPg

]]>https://forum.kiasuparents.com/post/2120601https://forum.kiasuparents.com/post/2120601Fri, 13 Oct 2023 00:56:17 GMT<![CDATA[Reply to O-Level Chemistry on Tue, 29 Aug 2023 15:37:35 GMT]]>Hi,


I’m looking for recommendations for Pure Chemistry tutor for my child in Sec 3. Tuition is in the east area. Appreciate recommendations pls.

Thanks!

]]>https://forum.kiasuparents.com/post/2117755https://forum.kiasuparents.com/post/2117755Tue, 29 Aug 2023 15:37:35 GMT<![CDATA[Reply to O-Level Chemistry on Wed, 05 Jul 2023 13:58:41 GMT]]>Should I do A Level Science even without foundation in Pure Science O Level Science?


https://youtu.be/yXYgGpwl5_0

]]>https://forum.kiasuparents.com/post/2112532https://forum.kiasuparents.com/post/2112532Wed, 05 Jul 2023 13:58:41 GMT<![CDATA[Reply to O-Level Chemistry on Tue, 04 Jul 2023 16:00:50 GMT]]>Hi all



Some students demonstrated misconceptions in their answers. This is the first video of the Series of Misconceptions in Chemistry - what are the common wrong answers and standard answers to the common questions.

https://youtu.be/PfCZyTbNxKg

]]>https://forum.kiasuparents.com/post/2112441https://forum.kiasuparents.com/post/2112441Tue, 04 Jul 2023 16:00:50 GMT<![CDATA[Reply to O-Level Chemistry on Fri, 30 Jun 2023 10:17:09 GMT]]>Hi,

Just wondering, do your children attend any O Level Science practical crash courses or preparatory classes for their upcoming O Level Science Practical exams? COuld you share with me your advice and past experiences?
Feel free to DM me. Thank you!

]]>https://forum.kiasuparents.com/post/2111963https://forum.kiasuparents.com/post/2111963Fri, 30 Jun 2023 10:17:09 GMT<![CDATA[Reply to O-Level Chemistry on Wed, 07 Jun 2023 13:21:34 GMT]]>Hi all


Predictions for 2023 GCE O Level Chemistry P2 and P3 as requested by some viewers.

https://youtu.be/z79JSUe8Wfw

]]>https://forum.kiasuparents.com/post/2110432https://forum.kiasuparents.com/post/2110432Wed, 07 Jun 2023 13:21:34 GMT<![CDATA[Reply to O-Level Chemistry on Wed, 07 Jun 2023 13:21:32 GMT]]>Hi all


Predictions for 2023 GCE O Level Chemistry P2 and P3 as requested by some viewers.

https://youtu.be/z79JSUe8Wfw

]]>https://forum.kiasuparents.com/post/2110431https://forum.kiasuparents.com/post/2110431Wed, 07 Jun 2023 13:21:32 GMT<![CDATA[Reply to O-Level Chemistry on Thu, 16 Feb 2023 15:31:33 GMT]]>Hi all


Some common mistakes to identify in students' answers. It could be helpful in revising for exams.

https://youtu.be/tENbuS6zHgY

]]>https://forum.kiasuparents.com/post/2097875https://forum.kiasuparents.com/post/2097875Thu, 16 Feb 2023 15:31:33 GMT<![CDATA[Reply to O-Level Chemistry on Mon, 09 Jan 2023 14:24:14 GMT]]>Should I do A Level Chemistry? Please share this video with friends who may need it.


https://youtu.be/mQrcIYurrQI

]]>https://forum.kiasuparents.com/post/2094605https://forum.kiasuparents.com/post/2094605Mon, 09 Jan 2023 14:24:14 GMT<![CDATA[Reply to O-Level Chemistry on Sun, 27 Nov 2022 22:22:11 GMT]]>

phtthp\" post_id=\"2090627\" time=\"1669563250\" user_id=\"35251:

Since there is no change to next year 2023 O-level Chemistry syllabus (SEAB),
no need

to buy these new series.
Our existing textbook, O-level \"Chemistry Matters\", is detailed and good enough !
Thanks phtthp..

]]>https://forum.kiasuparents.com/post/2090638https://forum.kiasuparents.com/post/2090638Sun, 27 Nov 2022 22:22:11 GMT<![CDATA[Reply to O-Level Chemistry on Sun, 27 Nov 2022 15:34:10 GMT]]>

MrsKiasu\" post_id=\"2090513\" time=\"1669506421\" user_id=\"43981:

I just read this.. for students doing O next year, will the MC new books help?
Since there is no change to next year 2023 O-level Chemistry syllabus (SEAB),
no need

to buy these new series.
Our existing textbook, O-level \"Chemistry Matters\", is detailed and good enough !

]]>https://forum.kiasuparents.com/post/2090627https://forum.kiasuparents.com/post/2090627Sun, 27 Nov 2022 15:34:10 GMT<![CDATA[Reply to O-Level Chemistry on Sun, 27 Nov 2022 14:41:27 GMT]]>

SG_KP1\" post_id=\"2090604\" time=\"1669554707\" user_id=\"188234:

This got me curious, now I see Chem and Bio moved from 2nd to 3rd edition while Physics moved from 4th to 5th edition.

We did not buy the LSS books in S1, only the pure or \"Matters\" books and I was hoping both kids could use throughout (as don't seem to be used all that often). I guess will see if either kid requires the newer versions (S3 kiddo's school seems to be fine with using prior/similar versions).
Yup, you’ve listed the new editions accurately. It should be in the latest booklist of all sec schools though.. Hm. Why are you curious?

Does the matters books overlap with more details, making the LSS books unnecessary? I didn’t take note that your child is in S3 IP too. 🙂

Autolycus posted that the new books have a substantially different approach and some overlap but the syllabus hasn't drastically changed, so it should be alright to use the previous edition.

]]>https://forum.kiasuparents.com/post/2090618https://forum.kiasuparents.com/post/2090618Sun, 27 Nov 2022 14:41:27 GMT