Hello. I came across this question in the May HL and SL paper. 0.05mol of sodium hydrogen carbonate was added to 50cm3 of 2.0M solution of citric acid. reaction given, temperature changed from 298K to 297K. cw 4.18. what is the enthalpy of this reaction?...
R1 What drives chemical reactionsHello Lauren,It is true that R3.2.2 states "Deduce redox half-equations and equations in acidic or neutral solutions" but the acidic solutions part refers to the need to add H+ or H2O to arrive at the half-equations...
Practice questions: R3.2 Oxidation & reductionI feel like Q8 is an extension question beyond the syllabus which states in R3.2.2 that students need to be able to "deduce redox...equations in acidic or neutral solutions....", and not alkaline as given here.
Practice questions: R3.2 Oxidation & reductionHello again Harprit, If you look at R3.4.1 which states "A nucleophile is a reactant that forms a bond to its reaction partner (the electrophile) by donating both bonding electrons." then it is clear that benzene is acting as a nucleophile...
R3.4 (AHL) Electron-pair sharing reactionsThanks. I have a follow up too, I was just looking at a MCQ on questionbank that I think is from a specimen paper about identifying nucleophiles. The answer states that benzene cannot act as a nucleophile, but isn't it acting as a nucleophile in this...
R3.4 (AHL) Electron-pair sharing reactionsHello Harprit,This is another example of where the syllabus appears to contradict itself. Yes, R3.4.14 states that the formation of the electrophile will not be assessed for the reaction between benzene and an electrophile but R3.4.6 states "Apply...
R3.4 (AHL) Electron-pair sharing reactionsHello Geoff. I'm struggling with electrophilic substiution a little here. The syllabus says there's no assessment for the formation of the electrophile. But without that how are students able to understand how the hydrogen gets removed from the benzene?...
R3.4 (AHL) Electron-pair sharing reactionsHello Austin,Coal originates from plant matter decomposed over millions of years under pressure and contains mainly carbon, hydrogen, oxygen, nitrogen, and sulfur. Question 1 gives the percentages of C, H, O and S by mass for different types of...
Data-based question (2)The fossil fuel data here is a little confusing. I assumed that reporting hydrogen percentage by mass would be H rather than H2. I don't know much about fossil fuels: Is it typical to have H2 and O2 present?
Data-based question (2)
Mani
May 2025. Do we need to look at moles of citric acid neutralised? so 0.05 mol NaHCO3 neutralizes 1/3 X 0.05?
R1 What drives chemical reactions