describe the kinds of energy changes that accompany physical and chemical change with an example each .
Answers
Explanation:
Melting and burning of candle wax is an example of both physical and chemical changes. Answer: Burning of wood is a example of both physical and chemical change. When wood is burnt the moisture present in it turns to vapour ,it is a physical change while it burns and generate CO2 is a chemical change
During phase changes, energy changes are usually involved. For example, when solid dry ice vaporizes (physical change), carbon dioxide molecules absorb energy. Meanwhile, when liquid water becomes ice energy is released. Remember that all chemical reactions involve a change in the bonds of the reactants
Answer:
Explanation: physical changes are mostly accompanied by temperature change of the substance.
Ex:- water is heated to convert it state of liquid into gas.
chemical changes are observed by :
I) emission of heat or light
II) formation of precipitate
III) evolution of gas
IV) colour change
Ex:- REACTION SHOWING COLOUR CHANGE-when an iron nail is placed in a blue colour of the solution of copper sulphate after sometime it is found that the intensity of the blue colour of the solution slowly decreases an iron nail becomes brownish in colour due to deposit machine of copper.
Fe + CuSO4 -----> FeSO4 +Cu
REACTION SHOWING FORMATION OF PRECIPITATE ::--
When Lead Nitrate solution is added to potassium iodide solution then I yellow precipitate of lead iodide is formed along with potassium nitrate solution.
2KI + Pb(NO3)2 ---> PbI2 + 2KNO3