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2013-01-30

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.

2013-01-24

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

2013-01-09

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