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Q19.

1.Pollutant Y is acidic.

2.When pollutant Y dissolves in rain water

3.it produces acid rain// causes air pollution.

Pollutant Y causes

1.Corroding/  corrode building.

2.Kill plants// increases acidity of soil// decreases pH of soil.

3.Kill aquatic organism// less.

●

Reject: destroy

 

 

 

 •Hard water contains Mg2+   and Ca2+

•   A – detergent

•   B  - Soap

Answer to Selected Topics 2012

Q17

Procedure

1.Measure [20 -200] cm3 of sodium hydroxide [0.1-2.0] mol dm-3 solution.

2.Pour the solution into a polystyrene cup.

3.Record the initial temperature of the solution.

4.Measure [20 – 200] cm3 of hydrochloric acid [0.1 – 2.0] mol dm-3.

5.Pour the solution into another polystyrene cup.

6.Record the initial temperature of the solution

7.Pour hydrochloric acid into sodium hydroxide solution.

8.Stir the mixture.

Record the highest temperature reached.                (7 marks)

Working

•Initial temperature of hydrochloric acid = T1

•Initial temperature of sodium hydroxide = T2

•Average initial temperature =  = Ta

•Highest temperature = Tb

•Heat given out = 200 x 4.2 x (Tb  - Ta) = x J                  1 mark

•Heat of neutralization =  -x/0.1 /1000    kJ mol-1                                 

                                      or         -x/0.1     J mol-1                  1mark

Answer to Essay Writing 2012

Q16.

Conversion of Fe3+ to Fe2+ ion

1.Reducing agent : Magnesium/ zinc/ any metal which is more electropositive than Fe (reject potassium, sodium and calcium)

2.Add [magnesium] to iron (III) chloride solution. (must be a soluble salt)

3.Stir/ shake/ Heat

4.Filter

5.Green precipitate is formed when sodium hydroxide  solution is added drop by drop until in excess. Or

  Dark blue precipitate formed when potassium hexacyanoferrate (III) solution is added.

Conversion of Fe2+ to Fe3+ ion

1.Oxidising agent as halogen:  Chlorine/ Bromine

2.Add chlorine water to solution of iron (II) sulphate.

3.Stir/ Shake/ Warm

4.Add sodium hydroxide solution or  potassium hexacyanoferrate (II) solution

5.Brown precipitate/ dark blue precipitate/blood red solution is formed.

Rate of reaction - All about factors!

The following was some activities carried out by my students doing "Catalyst factor on Rate of Reaction".

The presence of catalyst will lower the activation energy of a reaction, but at the same time, make sure you all remember that there is no increase in frequency of collision.

The increase of rate of reaction is caused by the lowering of activation energy in the reaction.
Therefore, there is an increase in frequency of effective collision in the reaction.

Check the video of decomposition of hydrogen peroxide solution as below:

Rate of Reaction

Rate of Reaction

Photos taken 28/1/2010

Class: 5 setia

Reaction of sodium thiosulphate and sulphuric acid :

Problem: How does the change of temperature of solution of sodium thiosulphate affect the rate of reaction?

Find it out!


More actions!!



Videos!

Rusting..... have you (Part II) ?

More pictures on day two...

Wow teacher I got the iron nail rusted!!!!