NO SPAM
Q. State the indications of a Chemical reaction , with examples ?
BEST ANSWER WILL BE MARKED AS BRAINLIST .
Answers
Answer:
The indications of a chemical change or a chemical reaction has occurred are the following:
- Formation of a precipitation.
- Change in color.
- Evolution of gas.
- Evolution or absorption of heat.
- Odor.
Evolution of gas:
The chemical reaction between zinc and dilute sulphuric acid is characterized by the evolution of hydrogen gas.
Zn(s)+H2SO4(aq)→ZnSO4(aq)+H2(g)
2.Change in colour:
The reaction between the lead nitrate solution and potassium iodide solution.
Pb(NO3)2(aq)+2KI→PbI2(s)+2KNO3(aq)
In this reaction colour changes from colourless to yellow.
3.Formation of precipitate:
The action of Barium Chloride on sodium sulphate.
BaCl2(aq)+Na2SO4(aq)→BaSO4(s)+2KNaCl(aq)
4.Change in temperature:
The action of dilute sulphuric acid on zinc:
Zn(s)+H2SO4(aq) => ZnSO4(s) + H2(g)
In this reaction, heat is evolved.
5.Change in the state:
When the wax is burnt in the form of the wax candle then water and carbon dioxide are formed. Wax is solid, water is a liquid whereas carbon dioxide is a gas.
Answer:
1)Evolution of gas. Some chemical reactions are characterised by the evolution of gas. ...
2)Formation of precipitate. Some chemical reactions are characterised by the formation of precipitate. ...
3)Change in colour. Some chemical reactions are characterised by change in colour. ...
4)Change in temperature. ...
5)Change of state