Question

State four conditions necessary for chemical reaction to take place?

Answer 1

Chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. The substance initially involved in a chemical reaction is known as a product and the chemical change yields one or more products.

Complete answer:
The four condition necessary for chemical reaction to take place are:
Heat: there are various reactions that take place only under a certain temperature. When heat is supplied to the reactants they go under reaction as heat also increases the rate for the chemical reaction. Example- there is a reaction between copper and sulphuric acid on heating that produce $S{O_2}$.
$Cu + 2{H_2}S{O_4}\xrightarrow{\Delta }CuS{O_4} + 2{H_2}O$
Light: light is also one of the factors that stimulate the rate of reaction. There are some reactions that undergo only in the presence of light. Example- hydrogen reacts violently with chlorine in the presence of diffused sunlight to produce hydrogen chloride.
${H_2} + C{l_2}\xrightarrow{{sunlight}}2HCl$
In the presence of sunlight, green plants manufacture food in the form of glucose using carbon dioxide and water as raw material.
$6{H_2}O + 6C{O_2}\xrightarrow[{chlorophyll}]{{sunlight}}{C_6}{H_{12}}{O_6} + 6{O_2}$
Catalyst: A chemical substance that changes the rate of reaction without undergoing any permanent changes during the course of the chemical reaction is said to be a catalyst. The process through which a catalyst changes the rate of chemical reaction is said to be catalysis. Catalysts can either increase or decrease the rate of reaction. Catalysts are of two types: positive and negative catalysts.
Example- Manganese dioxide acts as a catalyst in the decomposition of potassium chlorate on heating at low temperatures.
$2KCl{O_3}\xrightarrow{{Mn{O_2}/240^\circ C}}2KCl + 3{O_2}$
Surface area: the rate of chemical reaction is slow if the surface area of the reactants is small as there is less chance to contact between the reactants. On the other hand, when the surface area is big, the rate of chemical reaction increases. So, in order to increase the reaction rate. The surface area of the reactant should be large. Example- when large sized granulated zinc is treated with dilute hydrochloric acid, they react together rapidly and form hydrogen gas and zinc chloride.
$Zn + HCl \to ZnC{l_2} + {H_2}$

Note:
Positive catalyst is defined as the catalyst which increases the rate of chemical reaction. For example- manganese dioxide, a positive catalyst, increases the rate of decomposition of hydrogen peroxide. $2{H_2}{O_2}\xrightarrow{{Mn{O_2}}}2{H_2}O + {O_2}$
Negative catalyst is defined as the catalyst which decreases the rate of chemical reaction. For example- glycerin is a negative catalyst that decreases the rate of decomposition of hydrogen peroxide into water and oxygen.
$2{H_2}{O_2}\xrightarrow{{{C_3}{H_5}{{(OH)}_3}}}2{H_2}O + {O_2}$