The InThinking Chemistry website has been a great resource to have. The multiple choice tests have been invaluable in diagnostic marking and the guides to each subtopic, along with their discussions of common pitfalls, have helped to guide and improve...

Richard Young, British International School of Cairo, Egypt

This is a valuable resource for the teaching of IB chemistry.

Carla Grilli, St. Leonard’s School, UK

The InThinking Chemistry Website will be of value to any IB Chemistry teacher. The website is packed full of resources including worksheets and topic tests with answers. The comments about teaching each topic and experimental work are helpful.

Toby Dowling, North London Collegiate School, UK

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Asessement of IB DP Chemistry for May 2021

3 March 2021

There is some confusion on social media about the arrangements the IB have put in place for the May 2021 assessment process as it very much... more

What home schooling is showing

22 February 2021

Good parents will ask their children what they have been doing in school and help them with homework etc. etc. However until now most parents... more

Subscriber comments

  • thank you for the prompt reply.
  • Hello Farah, I think this is difficult to answer generally as it very much depends upon the context. How valid is the literature value? The most likely scenario is that it is a well-known value and comes from several different reliable sources....
  • HI Geof, please do guide me on the validity of the results of an IA that has a very high percentage error when compared to literature value. If the conclusion is drawn 'fully consistent with the experimental data' however is not close to literature...
  • 9 Apr Geoffrey Neuss
    Entropy & spontaneity
    Hello Xiaodan, The reversible decomposition of calcium carbonate is actually a heterogeneous system so is not covered under equilibrium on the IB syllabus. However students can probably understand that solids are not present in the equilibrium...
  • 9 Apr Xiaodan Wang
    Entropy & spontaneity
    Dear Geoffrey, I have a question about entropy. My students came across this question and the correct answer is I and II. Which ones of the condition on this following reaction are going to increase the entropy? CaCO3 (s) CaO(s) + CO2(g) I....
  • Hi Dawn, The current version of the Chemistry guide clearly states for Paper 3 that Section A: contains “one data-based question and several short-answer questions on experimental work.” Separately the IB has said that there will be no...
  • Will any of paper 2 contain lab-based questions like Section A of paper 3?
  • 28 Mar Geoffrey Neuss
    MC test: Graphical techniques
    Hello Stephanie, Volume is directly proportional to the absolute temperature so V = 0 cm3 when T = 0 K. The slope of Graph 2 is correct but the line does not go through the origin. The units of oC in Graph 4 are converted into K by adding 273....
  • 28 Mar Stephanie Seymour
    MC test: Graphical techniques
    Hi Geoffrey, I did not get Q1 correct on this MCQ, Can you elaborate more. I assumed that the answer would not be anything with a degrees celcius on the scale. Thank you
  • 26 Mar Sonja De Beer
    Strong & weak acids & bases
    Thank you so much. One of my students determined Ka for ethanoic acid at different temperatures, looking at his data, the Ka increased at higher temperatures - as expected for endothermic reactions - but then reading your comments about ethanoic...
  • 26 Mar Geoffrey Neuss
    Strong & weak acids & bases
    Hi again Sonja, I would expect Ka to increase at higher temperatures as the value of equilibrium constants for endothermic reactions increases as the temperature is increased. (Le Chatelier's Principle) However for many weak acids the dissociation...
  • 26 Mar Geoffrey Neuss
    Hi Sonja, It is endothermic. Basically two processes are occurring. The bond to the hydrogen atom in the undissociated acid has to break which is an endothermic process but then the ions formed hydrate which is an exothermic process. Overall...


Chemistry for the IB Diploma (Oxford IB)

The new edition of the Study Guide (which has sold over 150,000 copies) by Geoffrey Neuss for first exams in 2016.

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