Chemistry Blog

Strength of Hydrogen Bond

Strength of Hydrogen Bond Qn: Which of these compounds has the strongest hydrogen bond, HF, H2O or NH3? How do we estimate the strength of hydrogen bond? Ans: HF. Due to the largest electronegativity difference between H and F. Followed by H2O and then NH3. Qn: But then why does water have the highest boiling […]

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Common mistake in drawing hydrogen bond

Common mistakes in drawing hydrogen bond One of the most common mistakes is to write the dipole across the hydrogen bond, e.g. A dipole exists as a pair, partial positive and partial negative. It also depicts the uneven electron density distribution in a covalent bond thus it first forms in a single molecule where the hydrogen […]

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My Last Class T-shirt

Thankful that i had the chance to teach such a wonderful bunch of students before i left the college. Even though i told them i didn’t need one as i wouldn’t have any occasion to wear it. Thank you 17S305, for my last class t-shirt 🙂 Home

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Tips for organic deductive questions

Organic deductive questions If the organic deductive questions gives the molecular formula, see if the number of C and H is comparable. In addition, if the molecule contains more than 6 carbon atoms, the compound is likely to contain a benzene ring. Even if C and H is not comparable, the degree of unsaturation can tell us […]

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Simple tips for pattern recognition questions

Tips for pattern recognition questions Tip #1: Use your highlighter. Complicated rearrangement of atoms can be followed simply by highlighting the example given. Do the same for the question you are given and you will be able to predict the reaction product easily! Tip #2: Number the carbon chain. This tip is more for those questions […]

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Changes to H2 Chemistry Syllabus Part 2

H2 Chemistry Syllabus 2017 Part 2 (part 1 here) H2 chemistry syllabus 2017 updates: Organic: Constitutional (structural) isomerism. Cis-trans isomerism, used to be geometric isomerism. Enantiomerism used to be optical isomerism. Nitrogen Compounds (proteins): Not required to learn primary – quaternary structures, as well as list major functions of proteins in the body. Not required […]

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Changes in H2 Chemistry syllabus 2017 – part 1

Theories of acids and bases *New! Arrhenius theory – acid produce H+ in water, base produces OH– in water. Bronsted Lowry theory – acid produces H+, base accepts H+. Conjugate pair concept. Lewis theory – acid as electron pair acceptor, base as electron pair donor. Gases: Vm = 22.7 dm3 at stp (1 bar, 273 […]

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Changes in weightage for H2 Chemistry syllabus 2017

‘A’ Level Chemistry Syllabus Overview of changes in weightage: Table taken from SEAB website All students required to take practical paper 4, including private candidates. This means that candidates retaking their A level chemistry paper this year will have to sit for a 20% weightage practical paper. Also, their previous SPA scores will not be counted. […]

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