Heat of Neutralization and the Strength of Acids and Alkalis

1. Heat of neutralization between a strong acid and a strong alkali is always -57.3 kJ mol^-1.  Why?

Heat of neutralisation is the sum of of energy absorbed during bond breaking in the acid and alkali and energy released during bond formation of water molecule from H⁺ ion and OH^- ion.  All the reactions form 1 mole of water. 


2.  Heat of neutralization for neutralization involving weak acid or weak alkali is less than -57.3 kJ mol^-1.  Why?
Weak acid/akali does not ionises completely in water. Some energy released during formation of water is used to ionises the weak alkali/acid.

Heat of Neutralisation

Definition :

Energy change when one mole of water is formed from the neutralization between one mole of hydrogen ion from an acid and one mole of hydroxide ions from an alkali.
  

5H students are carrying out experiment to determine heat of neutralisation between an acid with an alkali.

Sharing Scientific Skills with SMK Puchong Jaya

It was my pleasure to have this opportunity to meet students from SMK Puchong Jaya.  We had a great sssion to learn and practise scientific skills evaluated in Paper 3 Chemistry SPM.

All the best to all Chemistry SPM candidates from SMK Puchong Jaya.

Polypropylene in Daily Life

Polypropylene as fabric

• The first polypropylene was produced by Professor Giulio Natta in 1954.
• It was later widely used  as injection moulding applications(Example: packaging, parts for electronic and electrical appliances, caps and closures, toys, luggage and a variety of household goods)
• Second largest use iof polypropylene is n fibres sector. (Example: thermal underwear & storage box)
• Film & sheet market: uses in the pacckaging of sweets, snack foods and cigarettes.
• The structure of polypropylene(polypropene)

For more info, visit

http://www.icis.com/v2/chemicals/9076430/polypropylene/uses.html



http://www.bpf.co.uk/Plastipedia/Polymers/PP.aspx

Kuiz Kimia Kebangsaan Malaysia 2011

86 students from my school were taking K3M 2011 this year. Hopefully more students will be awarded Sijil Merit, Sijil Kepujian & Sijil Cemerlang.

Pocket Warmer

This pocket warmer use chemicals that react to release heat.  The heat given off through exothermic reaction can be used to warm up body.  Mountain climbers bring pocket warmer  when they are high in the mountain. It can be used to lessen the pain of aching muscles.

Chemistry Form 5 Mid Year Exam SBP 2011

Please click here to download the Paper 1, 2, 3 & answer scheme.

This exam covers all topic in Form 4 and chapter 1 & 2 in Form 5.

A good tools to review how much you are ready for SPM.

Numerical Problems Involving the Factors that Affect the Rate of Reaction

Numerical Problems Involving the Factors That Affects the Rate of Reaction

How to Determine Empirical Formula of Magnesium Oxide

Revision Guide for Carbon Compounds

Carbon Compound Ver Diagram

Electrolysis of Copper(II) Chloride

The usage of cartoon in explaining the concept of electrolysis copper(II) chloride solution. Another alternative for students to understanding an abstract concept in chemistry.

Esterification Reaction

Esterification occurs between carboxylic acids and alcohols.

The colourfull notes from my students(5H) show reaction between ethanoic acid and different alcohols(methanol, ethanol, propanol and butanol).

Isomers of butene

Isomers of butene

Isomerism occurs in alkene due to

1. branching
2. position of carbon-carbon double bond

Photos show possible isomers for butene, C₄H₈.  Can you draw their strutural formulae and name them?

Their names are as follows:

Top: but-1-ene
Left: 2-methylprop-1-ene
Right: but-2-ene

Carboxylic Acids

General formula of Carboxylic acids: C_nH_2n+1COOH, n = 0, 1, 2.....
All the carboxylic acids have the same functional group, which is carboxyl group, -CO

Can you write molecular formulae and draw structural formulae for the molecules in the album above?

Feel free to drop your answers in the comment box.

Science & Technology Week 2011

Date: 11- 15 April 2011
In commerating International Year of Chemistry 2011, school has planned a series of activies as follows:

1. Essay Writing Competition(EWC)

    Theme: Chemistry – Our Life, Our Future
     *limited to 3000 words only.  For more details, click here.
 
Open to all students. Essay of the winners will  be submitted by the Principal of the school for the National level EWC.  Grand prize is waiting as the first prize winner in the national level will be fully sponsored to attend the closing ceremony of International Year of Chemistry in Brussels, Belgium from 1 - 3 Dec 2011.

2. Atomic Structure Design

    Use your own imagination and contruct your own 3D atomic model. You're free to use any materials.

3. My Periodic Table!

    What is your own version of Periodic Table of Element! Prepare one and share with us. The creative one will be the winner!

4. Chemistry Quiz

    Date: 11 April 2011
    Topic: Numerical Problems relating the concept of moles, chemical equation & concentration.
    4 students will be chosen randomly from each form 5 on the day of event to take part of the quiz. The more question you answer correctly, the nearer you are to the grand prize!

5. Karnival Kimia Malaysia(K₂M) 2011

    Date: 15 April 2011
   A bus of 40 students from our school will attend K₂M which will be held in National Science Centre.  A series of activities is waiting us : poster exhibition, demonstration and hands-on experiments, slide and video shows, talks & lectures on the theme and sub-themes, quiz and competition, etc.