RATE OF REACTION (KADAR TINDAK BALAS)
Explaning the rate of reaction
When we
talk about rate of reaction, it is always depending on how fast the reaction
takes place in an experiment. It can be either fast reaction, or slow reaction,
as it is a measurement of speed.
Scientifically, the rate of reaction is defined by change in amount of reactant or product against time. For instance, when a gas is produced during a reaction, so rate of reaction is the change in volume of the gas produced against time. Another example is when the mass of reactant is decreased, thus the rate of reaction is the change in mass of the reactant against time.
Scientifically, the rate of reaction is defined by change in amount of reactant or product against time. For instance, when a gas is produced during a reaction, so rate of reaction is the change in volume of the gas produced against time. Another example is when the mass of reactant is decreased, thus the rate of reaction is the change in mass of the reactant against time.
Rate of
reaction is inversely proportional to time of reaction (1/time) as the smaller
the value of time (shorter time), the greater the value of 1/time. Because of
that, when a reaction takes shorter time to complete, therefore the rate of
reaction is high. On the other hand, when a reaction takes longer time to
complete, therefore the rate of reaction is low.
Rate of reaction=1/(time of reaction)
Examples
of high rate of reactions or fast reactions are burning of magnesium ribbon
with oxygen, precipitation of lead (II) chloride by mixing sodium chloride
solution and lead (II) nitrate solution; and production of carbon dioxide
sodium carbonate (marble) reacts vigorously with dilute hydrochloric acid.
Meanwhile, examples of low rate of reactions or slow reactions such as
photosynthesis process, corrosion of metals and burning of copper with oxygen.
Measuring the rate of reaction
The
rate of reaction can be measured by looking at observable changes during the
reaction takes place such as;
a) Reduction in mass of reactant
b)
Increase in mass of product
c) Production of precipitate
d)
Release of gas
In all reactions, the quantity of
reactants will decrease while the quantity of products will increase. Thus, the
rate of reaction can be measured as follows;
Rate of reaction=(reduction of reactants quantity)/time
or
Rate of reaction=(increase of products quantity)/time
As an
example, a reaction between calcium carbonate with hydrochloric acid will
produce calcium chloride, water and carbon dioxide.
CaCO3 +
2HCl → CaCl2 + H2O + CO2
From
that chemical reaction, the rate of reaction can be determined by following
methods
Rate of reaction=(reduction of calcium carbonate mass)/time
or
Rate of reaction=(increase of carbon dioxide volume)/time
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