After communicating with several students, i realised that many come to his Chemistry blogsite to look for more F-R-E-E O Level Chemistry Questions and Solutions/Answers. In fact, you can find them at “Chemistry Notes & Tips” under CATEGORIES on the right hand side column of this blog. Seems like many students are not sure how to find the topics of their interest.
I have decided to put up a “NAVIGATION VIDEO” on this blog to teach all readers how to maximise their learning in this blog. Stay Tuned for it!
Meanwhile, if you are looking for specific O Level Chemistry Topics, check the following links for wealth of information and tips:
- Atomic Structure
- Kinetic Particle Theory
- Bonding & Structural Properties
- Balancing Chemical Equations
- Mole Calculations
- Rate of Reaction
- Periodic Table & Group Trends
- Energy Changes
- Redox
- Electrolysis
- Metals & Reactivity Series
- Organic Chemistry
- SPA / Chemistry Practical Tips
Hope this helps you in learning Chemistry and scoring the grades you desire.
PS: Drop me a comment, i would love to hear from you. =)
[...] that, please check also the blogposts that i have discussed in 2008 on O Levels Chemistry Exam Questions & Answers (in topical basis). Again, this contains archives (older blogposts) on questions that were discussed for the 2008 [...]
what’s the color change at da end of a titration experiment with fe 2+ ions and potassium manganate? explain please!!
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sean Reply:
June 2nd, 2009 at 1:33 am
Hi saba,
Although titration is carried out in this example, this chemistry question should be placed under the chapter of “REDOX: Reduction & Oxidation”.
Fe2+ are very good reducing agent.
KMnO4 is commonly used to test for a reducing agent.
In this case, KMnO4 change from Purple to Colourless.
Hope this information helps.
To Your Academic Success in Chemistry,
Sean Chua
Master Trainer @ SimpleChemConcepts.com
Author of Up Your Chemistry Grades Now! book
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QCM Reply:
November 9th, 2010 at 7:43 am
Or we may use take the time needed for the potassium permanganate to decolorize with known concentrations of iron(II) ions (or for the solution to turn reddish-brown/pale yellow). Plot a best-fit curve and repeat the whole experiment again with the unknown concentration of iron(II) ions. Lastly, read the concentration of your graph. However this method is seldom used in Chemistry, but it can work though. It may be used in Biology to check the blood plasma glucose concentration as glucose is also a reducing agent.
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I guess we have to say ACIDIFIED potassium manganate(VII) in order to have the colour change from purple to colourless. In neutral or alkaline condition, brown precipitate of manganese(IV) oxide, MnO2 is obtained instead.
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