Nota Terkini

Friday, March 27, 2009

[Chemistry Form 5] Rate Of Reaction

The rate of reaction can be obtained by measuring the

* Time taken for the reaction to be completed

The rate of a reaction is inversely proportional to the time taken for the reaction to be completed.

Rate = 1/Time

* Amount of product formed or reactant used up per unit time

Example:

When a sodium thiosulphate solution is reacted with hydrochloric acid, the rate of the reaction can be measured by timing how long it takes for a sufficient amount of sulphur to form so that a dark cross drawn on a oiece of card below the reaction flask can no longer be seen.

1) What is the rate of reaction if the time taken for the cross to disappear is 50 seconds?

Answer: Rate = 1/Time = 1/50s = 0.02/s

2) Write the chemical equation for the reaction above.

Answer: Na2S2O3 (aq) + 2HCl (aq) --> 2NaCl (aq) + S (s) + SO2 (g) + H2O (l)

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