Question

1. How can you use chemical formulas to determine if a change is either chemical or physical?

2. How do particles differ after a physical change?

3. How do particles differ after a chemical change?

4. Your friend says, “Chemical changes are caused by an input in energy. In physical changes, there is no transfer of energy.” Is your friend correct? Why or why not?

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Answer 1

Answer:

1,2,3, are in sequence

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Answer 2

1. by performing chemical analysis, such as mass spectroscopy, on the substance to determine its composition before and after a reaction. “chemical reaction.
2. after a physical changes no new materials are formed and the particles do not change apart from gaining or losing energy.Particles   same unless and until there is a chemical change. The matter is solid, liquid or gas only their arrangement, energy and movement changes.
3. after a chemical changes new substances are formed  the process is  difficult to reverse. During chemical changes particles do change with atoms or ions by  regrouping . Bonds (links) between atoms break and new ones form and energy is either given out or taken in.
4. "Yes",  Chemical reactions   involve changes in energy due to the breaking and formation of bonds. Reactions in which energy is released are exothermic reactions,  those  are  taking heat energy are called as endothermic.
5. "YES" When physical changes occur, they are generally accompanied by a transfer of energy. The law of conservation of energy states that in any physical process, energy is neither created nor destroyed. ... During most processes, energy is exchanged between the system and the surroundings.