Butane in Bunsen Burner in School Laboratory

A common Bunsen burner used in the school laboratory.  It consists of butane gas. 

The butane gas in the cartridge under combustion in the presence of oxygen gas produce carbon dioxide and water. 

Chemical equation for complete combustion of butane. 

When there is insufficient of oxygen(the hole of Bunsen burner is closed), incomplete combustion occurs and sooty flame is produced. 

New York Call for a Ban on Styrofoam

What we commonly call  Styrofoam is more technically known as foamed polystyrene.

New York City Mayor Michael Bloomberg recently just plans a ban on Styrofoam food packaging  from stores and restaurants. 

Common uses of Styrofoam

• disposable coffee cups, plates
• cushioning material in packaging

The structure of polystyrene. 

Number of Atoms & Number of Molecules

Which of the following substance contains 1.204 x 10²⁴ atoms?

A  1 mol of nitrogen gas
B  1 mol of ammonia
C  1 mol of water
D  1 mol of argon

Many of my students choose the wrong answer in the current topical test.

1 mol of nitrogen gas consists of 1 x 6.02 x 10²³ molecules. 

Number of atoms in 1 mol of nitrogen gas is 2 x 6.02 x 10²³ .
(Each nitrogen, N₂ molecule consists of 2 nitrogen atoms)

1 mol of ammonia consists of 1 x 6.02 x 10²³ molecules

Number of atoms in 1 mol of ammonia gas is 4 x 6.02 x 10^23.
(Each ammonia, NH₃ molecule consists of 4  atoms) 

1 mol of water consists of 1 x 6.02 x 10²³ molecules

Number of atoms in 1 mol of water is 3 x 6.02 x 10²³
(Each water, H2O molecule consists of 3 atoms) 

1 mol of argon consistss of 1 x 6.02 x 10²³ atoms. 


The correct answer : A

Examples of Hydrocarbons

The above figure shows different examples of carbon compounds.
As we exam the structure of every molecule, each carbon atom is  with bonded with other atoms(carbon atoms/hydrogen atoms) through either single bond, double bond or triple bond.

Which examples shown is saturated hydrocarbons?

Saturated hydrocarbons are Organic compounds containing only carbon & hydrogen atoms only.

Interpreting Graph relating to Rate of Reaction

Hydrogen peroxide decomposes to water and oxygen.



In this reaction, rate of reaction is measured by the changes in volume of oxygen gas released per unit time.

Rate of reaction can be shown by a steeper curve.

Curve Q has  a steeper curve.  The rate of reaction is higher.   The possible factors affecting the rate of reaction is : size, concentration, temperature, pressure and catalyst.  The possible factor mostly is concentration.  Higher concentration, higher rate of reaction.  

Curve Q shows that volume of gas released is lesser. 

Volume of oxygen gas released depends at the quantity of reactant(in more specific, number of moles of hydrogen peroxide used).   

Number of moles of hydrogen peroxide used in the initial experiment is 

(0.1 x 25)/1000 = 0.0025 

After determining number of moles of hydrogen peroxide given in A, B, C & D. 

Only the number of moles of hydrogen peroxide in C is the smaller than 0.0025.

The correct answer : C

Determining Rate of Reaction

In the reaction between limestone powder(calcium carbonate) hydrochloric acid, 17 cm³ of carbon dioxide that produced is in 3.5 minutes. 

Average rate of reaction is 17 cm³/3.5 min

But, during the second minute, only (12.5 - 7.5) cm³ of carbon dioxide gas released in 1 minute time, 

Average rate of reaction during the second minute is

(12.5 - 7.5) cm³ / (2 - 1) min 

The correct answer is : C

Slow Reaction

Slow reaction has low rate of reaction. It takes a long time for the reaction to be complete.
Examples of slow reaction :

Rusting of Iron
An iron takes a long time to react with oxygen and water to form rust(brown solid on the iron nail), which is known as hydrated iron(III) oxide, Fe₂O₃.3H₂O.

*credit to Wikipedia

Formation of stalagmites
Stalagmites are formed due to the dripping of mineralized solutions and the deposition of calcium carbonate. Normally this stalagmites formation only occurs under certain pH conditions within the underground cavern.











Ripening of fruits

Question Analysis of Paper 1 Chemistry SPM 2012

Chemistry SPM 2012 Paper 1 Question Analysis from sweemoi khor

2012 SPM Chemistry (Paper1) Answer

1.B 2.A 3.A 4.A 5.C 6.D 7.C 8.D 9.A 10.D
11.B 12.A 13.D 14.D 15.A 16.C 17.B 18.A 19.A 20.B
21.C 22.C 23.B 24.A 25.C 26.C 27.D 28.D 29.D 30.B
31.B 32.B 33.B 34.D 35.B 36.C 37.C 38.A 39.C 40.C
41.A 42.A 43.B 44.D 45.D 46.D 47.C 48.A 49.A 50.D

Common Sources of Radiation Used in Malaysia

Medical Field

Widely used in Nuclear Medicine, radiology & Radiotherapy, for diagnosis purposes & medical research. 
Common radioisotopes used : Technitium-99, Cobalt-60, Cesium-137, Iodine & Radium 226

In Industry

Used in industrial application such as gauging, oil logging, industrial radiography, analyytical purposes for minerals & soil samples, quality assuarance for electronic componenets & tracer 
technique applications. 
Common radioisotopes used : Americium-241, Berryllium-9, Cobalt-60, Cesium-137, Stronitium-90, Iridium-192, Argon-41, Kripton-85, Sodium-24.

In Research

Mostly for research activities in agriculture, medicine & nuclear sciences. 
Common radioisotopes used : Phosphorus-32, Technitium-99, Cobalt-60, Cesium-137, Gold-198.

Source : Atomic energy Licensing Board, Malaysia

Crystallization of Lead(II) Iodide

1. What is the special characteristics of lead(II) iodide you observe from the video above?
2. What are the reactants used to prepare lead(II) iodide?

Naming of Carbon Compounds

Are you able to identify names of 10 different carbon compounds?
It's a trial version using Wordle.

Modul Perfect Score SBP (Kimia) 2012

Perfect Score SBP 2012 is prepared by a group of experienced teacher.   It consists :

1. Answering techniques for Paper 2 & 3 SPM
2. 5 sets of questions which arranged according to topics. 

I believe it help students to get a thorough revision through the exercises. You may download through the link provide. 

Download

Any questions that need clarification from Chem2u, please post by using the link at the comments below this post. A text box will appear.  Remember to include your name before you click the button Publish. 

Paper 2 Trial Chemistry SPM Terengganu 2012

All 5B, 5F & 5G Students

 Please attempt the following questions in Paper 2 Trial Chemistry SPM Terengganu 2012.

Question 7 : Salts

Question 8 : Redox Reactions

Question 9 : Carbon Compounds

Question 10 : Rate of Reaction

All of you are welcomed to post your answer or ask questions here. 
Remember : Please click at the comments below this post. A text box will appear.  Remember to include your name before you click the button Publish.  A best response & active participant will be acknowledged by Chem2u after the discussion is closed on 29 October 2012. 

Peperiksaan Percubaan SBP Chemistry 2012

Paper 1

Paper 2

Paper 3

Answer Scheme

Credit to Mr Adura