Chemistry Form 4: Chapter 7 - Preparing a Standard Solution

• Standard solution is a solution whose concentration is known accurately.
• The solution is normally expressed in mol dm^-3
• Standard solution can be prepared by using a calculated mass of solute or dilution method from concentrated solution.

MAKING STANDARD SOLUTIONS FROM CONCENTRATED AQUEOUS

Equipment typically used when preparing a solution in a volumetric flask includes the volumetric flask and its glass stopper, pipette, a medicine dropper, and a funnel. Water can be delivered from the beaker or wash bottle.

Procedure:

MAKING STANDARD SOLUTIONS FROM CALCULATED MASS

Procedure:

• Volumetric flask is more accurate than beaker for the preparation of standard solution.
• Water is added using dropper to bring the solution to the graduation mark.
• Standard solution must be covered by stopper to prevent the contamination of the standard solution by foreign particles.
• After preparing the standard solution, shake it well to ensure thorough mixing.

Logos Hope Docked at Penang

Vision and Purpose: 

Bringing Knowledge
Over 40 million people in 158 different countries have walked up the Ships gangway to visit one of our ships' floating book fairs. For many, it is their first ever opportunity to purchase good quality literature at a fraction of its retail value. Many people without the means to study have learnt vital skills and been able to enhance their lives through a purchase from over 6,000 available titles, including books for studies, professional and career interests, individual development and personal growth.
Cultural variety abounds with over 40 nations meeting on board. For visitors, opportunities to meet crew provide insights into the wider world, while interactive programmes offer fresh perspectives on living in a multi-cultural society. For volunteer crew, time on board the ships provides a chance to experience countries and cultures for themselves, as well as opportunities to learn valuable skills for the future.

Bringing Help
Sailing from port to port, crew experience the needs of the world first-hand. Being in a position to help – whether by donating supplies, building a house, or offering a listening ear – is both a privilege and a responsibility. The ships seek to bring aid and relief in situations of particular need as a practical demonstration of God’s love for mankind. Coupled with their promotion of education, this approach aims not only to alleviate immediate needs, but also to bring long-term change in each community.

Bringing Hope
Every person has a inbuilt need for hope and purpose in life. Our volunteer crew seeks to bring new hope by their service on board as a community focused on the needs of others. They offer hope through their actions and their interaction with others. Every crewmember has a story to tell of a transformation in their personal life that has given them hope and purpose.

Come and visit the world's largest floating book fair in Penang

Physics Form 5: Chapter 5 - Radioactive Decay

Radioactive decay is the breaking up of unstable nuclei into more stable nuclei with the emission of radioactive rays.

There are three main types of radiation:

• Alpha decay
• Beta decay
• Gamma decay

A) Alpha decay

The reason alpha decay occurs is because the nucleus has too many protons which cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is emitted. The way it works is that the Helium nuclei are in constant collision with the walls of the nucleus and because of its energy and mass, there exists a nonzero probability of transmission. That is, an alpha particle (Helium nucleus) will tunnel out of the nucleus

 

B) Beta decay

Beta decay occurs when the neutron to proton ratio is too great in the nucleus and causes instability. In basic beta decay, a neutron is turned into a proton and an electron. The electron is then emitted

C) Gamma decay

Gamma decay occurs because the nucleus is at too high an energy. The nucleus falls down to a lower energy state and, in the process, emits a high energy photon known as a gamma particle.

 

Physics Form 4: Chapter 4 - Specific Heat Capacity

Specific Heat Capacity is the amount of energy (in Joules) needed to increase the temperature of 1 kg of a substance by 1 degree Celsius

Different material have different specific heat capacity value

High specific heat capacity ===> good insulator of heat

Low specific heat capactiy ===> good conductor of heat

Click on the diagram below to play!
 

Chemistry Form 5: Chapter 3 - Conversion of Iron (II) to Iron (III) and Iron (III) to Iron (II)

Conversion of Fe²⁺ to Fe³⁺

Oxidising agent : bromine water Reducing agent :  Fe2+ ions Oxidation half equation: Fe2+ ions lose electrons and are oxidized to Fe3+. The presence of Fe3+ ions is confirmed by the formation of brown precipitate with excess of NaOH solution.                      Fe2+ -------->    Fe3+    +     e Reduction half equation: Bromine molecules which give bromine water its brown colour gain electrons and are reduced to colourless bromide ions.                      Br2    +    2 e   ------->  2 Br- Overall ionic equation: 2 Fe2+   +    Br2    ---------->  2 Fe3+    +    2 Br- Observation: Brown bromine water decolourises. The solution changes colour from pale green (Fe2+)  to yellow (Fe3+).

Conversion of Fe³⁺ to Fe²⁺

Oxidising agent : Fe2+ ions Reducing agent :  zinc Oxidation half equation: Zinc atoms lose their electrons and are oxidized to zinc ions, Zn2+. Zinc powder dissolves in iron (III) chloride. Zn    ------->   Zn2+    +    2 e Reduction half equation: Fe3+ ions accept electrons and are reduced to Fe2+. The presence of Fe2+ ions is confirmed by the formation of green precipitate with excess of NaOH solution. Fe3+    +     e    -------->    Fe2+    Overall ionic equation: 2 Fe3+   +    Zn    --------->  2 Fe2+    +    Zn2+ Observation: Zinc powder dissolves into solution. The solution changes colour from brown (Fe3+) to pale green (Fe2+).

Page accuses Putrajaya of ‘buying time’, wants English-language option restored

The MalaysianInsider News, August 17, 2011 By Debra Chong

KUALA LUMPUR, Aug 17 — The Parent Action Group for Education Malaysia (Page) wants Putrajaya to restore ‘teaching science and maths in English’ option before it kicks off a new policy next year.

Its vice-chairman, Sulaiman Mahran, ticked off Deputy Prime Minister Tan Sri Muhyiddin Yassin for saying the Education Ministry will study further the possibility of using two languages to teach the two subjects in national schools, as reported by state news agency Bernama yesterday.

“It’s only buying time until 2012 when the MBMMBI will be fully implemented,” Sulaiman said in a statement, referring to the “Upholding the Malay Language and Strengthening Command of English” policy that is to take over the existing language policy for science and maths (PPSMI).

The English-language lobbyist pointed out that the long-term advantages of English had been identified during the Mahathir administration but that its implementation was miscarried during the Abdullah administration.

“Datuk Seri Najib’s administration should repair its implementation, not dismantle it,

“What should be studied deeper is MBMMBI, which is clearly defective because it reduces the students’ exposure to English by 50 per cent,” Sulaiman said.

Prior to the Sarawak polls on April 16, Prime Minister Datuk Seri Najib Razak had also announced he would consider using dual languages as the medium of instruction for Mathematics and Science in schools.

PPSMI was first introduced in 2003 but the Education Ministry decided last year to stop it by 2012 after consulting with teachers and parents around the country.

In the uproar that followed after PPSMI was abolished, Putrajaya introduced MBMMBI, which will see the teaching of Mathematics and Science revert to Bahasa Malaysia from 2012 while more contact hours for English would be offered in order to improve students’ skills in the language.

In May The Malaysian Insider reported that the Najib administration had not decided on switching back to English for Science and Mathematics (PPSMI) because several Cabinet ministers felt any change would be another embarrassing flip-flop.

The Education Ministry has also announced it would hire 10,000 teachers to teach English in local schools.

Najib has also got a promise from the United States to send Peace Corps volunteers to teach the language in the country.

Chemistry Form 4: Chapter 7 - Strength of Acid

The strength of an acid depends on the degree of dissociation of the acid in water to produce hydrogen ions and anions. The pH of an acid solution depends on the concentration of hydrogen ions.

Strong Acid	Weak Acid
·     Strong acid have a higher degree of dissociation. ·     A strong acid is an acid which dissociates completely in water to produce a high concentration of hydrogen ions. ·     Thus, pH value for strong acid is lower than weak acid.	·     Weak acid have a lower degree of dissociation. ·     A weak acid is an acid which ionises partially in water to produce a low concentration of hydrogen ions. Only a part of the molecules ionises and the remaining still in covalent molecules. ·     Thus, pH value for weak acid is higher than strong acid.

Click on the diagram below to play!

Weak Acid

Strong Acid

Examples of strong acid

HCl	Hydrochloric acid		HNO3	Nitric acid
HBr	Hydrobromic acid		H2SO4	Sulfuric acid
HI	Hydroiodic acid		HClO4	Perchloric acid

Examples of weak acid

Physics Form 5: Chapter 5 - Radioactivity

Introduction

In 1896, Bequerel, a French physicist discovered that crystals of Uranium salts emitted penetrating rays similar to X-rays which could fog photographic plates. Two years after this Pierre and Marie Currie discovered other elements: Polonium and Radium which had this property. The emission was known as Radioactivity.

 
The Stability of Nuclei

Protons and Netrons are held together in the nucleus of an atom by the strong-force. This force acts over a very short distance of about ~1 fm, (10^-15m) and over this short distance it can overcome the electromagnetic repulsion between the positively charged protons. Nuclei with radii that are within the range of the Strong force are stable. As atomic number increases the radius of the nucleus also increases and the element becomes unstable. This instablity manifests itself as the emission of particles or energy from the nucleus. The elements with atomic number greater than 82 are radioactive.

Radioactivity is the spontaneous and random emission of radioactive rays from unstable radioactive materials to become more stable material.

Spontaneous	Cannot be influenced by any physical factors such as temperature, pressure and time.
Random	Emission occurs at irregular intervals and does not occur at the same rate.

There are 3 types of radioactive rays:

• Alpha radiation
• Beta radiation
• Gamma radiation

The World's Longest Bridge Over Water

The world's longest bridge over water, connecting China's port city of Qingdao with an airport on the other side of Jiaozhou Bay, has finally opened. The bridge is 26.4 miles long, making it the longest bridge in the world.

The building of the bridge has generated some amazing statistics:

• It stands on 5,200 pillars.

• It cost around $1.5 billion to build.

• It uses enough steel for almost 65 Eiffel Towers - 450,000 tons, along with 81 million cubic feet of concrete.

• It can withstand a magnitude 8 earthquake, typhoons, or the impact of a 300,000 ton ship.

The bridge will hold its title for about 5 years; in 2016, a 30 mile bridge is expected to be completed that links Hong Kong with Macao and Guandong province. 

 

Physics Form 4: Chapter 4 - Thermal Equilibrium

When two substances having different temperatures are introduced or kept together, heat energy flows from a substance at higher temperature to a substance at lower temperature. Also, heat continues to be transferred till their temperatures are equalized.

• Thermal equilibrium is the situation where there is no net heat flow between the two bodies at the same temperature.
• That is the rate of heat absorption equals to the rate of heat dissipation at the same temperature.
• Two bodies are said to be in thermal equilibrium when:

a)      they are at same temperature

            b)    the net rate of heat flow between them is zero.

Click on the diagram below to play!

 

Badminton World Championship 2011

Physics Form 4: Chapter 3 - Application of Archimedes Principle (Hydrometer)

• Hydrometer is used to measure the density of liquid.
• The hydrometer works on the principle that a floating object displaces a volume of liquid whose weight is equal to the buoyant force.
• Hydrometer will sink deeper in the less dense liquid but float higher in the denser liquid.

   Design of a hydrometer

Characteristic	Explanation
Lead shots are added to the base	·     To lower the centre of gravity of the hydrometer ·     So that, hydrometer can float upright in a liquid.
Thinner and longer glass tube is used	·     Will give a larger scale distance and can detect small changes in the densities.
Big bulb at the base is used.	·     So that more liquid can be displaced
For calibration, hydrometer is allowed to float in lower density and higher density liquid	·     Liquid level in lower density and higher density is marked. The space between the two marks is divided into a number of equal divisions that give density readings.

Penang Clan Jetty History

Bo Lang Chai (Forgotten) from Pusat KOMAS on Vimeo.

Chemistry Form 4: Chapter 7 - Concentration of Solution (Molarity)

• Molarity is defined as moles of solute per liter or 1 dm³ of solution.
• Molarity is used to express concentration of solution.
• 1 dm³ = 1000 cm³
• The unit of molarity is mol dm^-3

Click on the diagram below to play!

Graduate Picks Former Teacher for University Grant

The Star Newspaper
GEORGE TOWN: A teacher's hard work did not go unnoticed by a former student who nominated her for a S$5,000 (RM12,300) grant from the Nanyang Techno-logical University, Singapore.

Chung Ling High School teacher Tan Lon Eng was nominated by Goh Lam Chye, 23, who was asked by the university's School of Humanities and Social Sciences to name two educators who had played important roles in guiding students, for the grant.
The grant allows Tan to choose a student from Chung Ling who will be given the opportunity to pursue studies at the university.

Goh, who recently graduated from the university, was chosen to select a candidate due to his academic achievement and active participation in co-curricular activities. “I feel honoured to be chosen as the university awarded the grants to only 22 students, including two other Malaysians. “I have decided to name the grant after Tan, who was my former teacher, in appreciation of her help,” Goh said here.

“It feels good to be able to help the juniors at my alma mater pursue their studies,” he said. Tan said she would name a student next year. “I need time to observe and choose the right candidate for the grant,” said Tan.
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Malaysian higher learning institutions should emulate the Singapore way in honouring the outstanding students and teachers. In my opinion, this recognition from Nanyang Technological University to Cikgu Tan from Chung Ling High School is better than our own Anugerah Perkhidmatan Cemerlang, APC to school teachers. Sometimes the APC is awarded based on seniority, preference and racial quota.

Physics Form 4: Chapter 3 - Application of Bernoulli Principle (Spinning Ball)

Let's we watch how Roberto Carlos do free kick.

Goal......goal......This was one of the best ever free kick. By the way, how Roberto Carlos did it?

• According to Bernoulli Principle, a ball which spins in the same direction of moving air will increase the velocity of the ball. The moving air in the opposite direction of the spin ball is slowed down.
• Higher velocity will produce lower pressure and vice versa.
• Because of this, the air pressure on one side is higher than that the other side. It produces a resultant force acting from high pressure to low pressure.
• Therefore, a spin ball curves.

 

More examples of spinning ball

Chemistry Form 4: Understanding of Acid and Bases

Acid is a chemical substance that dissolves in water to produce hydrogen ions, H⁺ ions. This causes the concentration of hydrogen ion in the solution to increase and the pH to drop.

According to the Arrhenius definition, when hydrogen chloride which is a gas HCl is dissolved in water, it dissociates to produce hydrogen ions and chloride ions in solution. This making HCl an acid when dissolves in water.

Without presence of water, the acid will not dissociate to produce hydrogen ions and it will not show acidic properties.

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Also, a base is a chemical substance that dissolves in water to produce hydroxide ions, OH^- ions. This causes the concentration of hydroxide ion in the solution to increase but decrease in concentration of hydrogen ion. This is why the pH increases when a base is added to water.

According to Arrhenius definition, sodium hydroxide, NaOH is a base because when it dissolved in water, the NaOH dissociates to produce hydroxide ions.

Without presence of water, the base will not dissociate to produce hydroxide ions and it will not show basic properties.

                                                 Acid                                       Base

Operational Definition	When added to water pH < 7	When added to water pH > 7
Arrhenius Definition	When added to water dissociates to release a hydrogen ion (H+)	When added to water dissociates to release a hydroxide ion (OH-)

The Swedish Chemist, Svante Arrhenius (1859-1927). The Arrhenius definition of acids and bases is an extension of his theory of electrolyte solution, which formed his 1884 doctoral thesis.