what is a chemical change
a chemical change is a change in which new susbtance(s) is/are formed
what are chemical change also called
chemical reactions
in a chemical reaction, what happens?
In a chemical reaction, substances callled reactants react with each other to form new substances called products
why does chemical changes occur(1)
chemical changes occur because of interactions between different kinds of matter, such as when substances are mixed
neutralisation and precipitation
why does chemical changes occur (2)
chemical changes can also occur because of interactions between matter and energy, such as heat, light or electricity
combustion, decomposition, and electrolysis
interactions between matter when mixed
combustion(burning)
(Thermal) decomposition
what are the different examples of chemical changes when mixed
reactions invloving acids and alkalis
precipitation reactions
oxidation reactions
interactions between matter and heat
decomposition by light
interactions between matter and electricity
Decomposition by Electrolysis
what is precipitation
Precipitation is the process in which an insoluble solid is formed when two solutions are mixed . The insoluble formed is callled a precipitate
what happens in oxidation reaction
a substance may react with oxygen to form a new substance, chemical reactions are :
1. Rusting
2. Respiration
what is respiration
respiration is the oxidation of food substances, like glucose, to release energy for cellular activities
for eg. glucose+oxygen–carbon dioxide +water
what is combustion
combustion is the burning of substances (such as fuels) in oxygen
what does combustion need
heating is required for combustion to take place
what is released during combustion
energy is released during combustion, usuallly in the form of heat and light
what are the similarities of combustion and oxidation
Both combustion and oxidation involves substances reacting with oxygen
how to differentiate combustion from the other examples of oxidation
Combustion requires heating, while the other exanples of oxidation may not require heatiing. During combustion, energy is released, usually in the form of heat and light
definition of decomposition
it is the process in which a compound breaks down into two or more substances
what is electrolysis
just need to understand
a technique using electricity to break down a compound to obtain its constituent elements
why are silver nitrate solutions stored in amber bottles?
expose to direct sunlight will cause it to decompose
important to note in photosynthesis
photosynthesis is not decommposition by light
how are acid rain formed
sulfur dioxide gas that is released into the atmosphere reacts with oxygen and water to form sulfuric acid, leading to the problem of acid rain
