I need help from chemists..Please..?

Question

What is physical and chemical changes?
How does each differs from another?
How about the exothermic and endothermic changes?
can you give examples?

May I know your sources? Thank you.

Answer 1

Look here: http://antoine.frostburg.edu/chem/senese/101/thermo/faq/exothermic-endothermic-examples.shtml

Physical changes occur when objects undergo a change that does not change their chemical nature. A physical change involves a change in physical properties. Physical properties can be observed without changing the type of matter. Examples of physical properties include: texture, shape, size, color, odor, volume, mass, weight, and density.

An exmple of a physical change occurs when making a baseball bat. Wood is carefully crafted into a shape which will allow a batter to best apply force on the ball. Even though the wood has changed shape and therefore physical properties, the chemical nature of the wood has not been altered. The bat and the original piece of wood are still the same chemical substance.
http://www.usoe.k12.ut.us/curr/science/sciber00/8th/matter/sciber/change.htm

Chemical changes occur all the time in our daily lives. A chemical change occurs when one kind of matter changes into another kind of matter. This process of change is called a chemical reaction. Observing a change in one or more chemical properties often identifies a chemical reaction. These include a change in color, the release of a gas, the formation of a precipitate (a solid that will settle out of a liquid or gas), and the absorption or release of heat. When two or more substances are mixed together and one of the changes listed above occurs, then a chemical change or reaction has taken place.
http://galileo.phys.virginia.edu/education/outreach/8thgradesol/ChemicalChg2.htm#background

Answer 2

A physical change never results in a new chemical being formed. A chemical change does - and the product often looks completely different from the reactants. That is how you tell the difference.

An exothermic chnage gives out heat to the surroundings, which get hotter. An endothermic change takes in heat from the surroundings, which get colder.

Answer 3

chemical changes result in the changed matter having some new chemical content, while in physical changes, the type of matter in the object stays the same.

eg:

Chemical = baking powder + vinegar makes CO2
Physical = Ice + heat makes water (in this example, the change can be reversed and the chemical content has not changed)

Answer 4

physical changes are usually mixtures as in wen they r mixed they can be easily separated e.g if iron fillings are mixed wit sand since iron is metalic it can be removed frm the mixture with a magnet.
chamical changes r those that are combined and are nt that easy 2 separate into their elements e.g zinc oxide

endothermic changes are reactions that take in heat frm the suroundings so if there is an endothermic raection occurin in a beaker and u touch the beaker ur hand will feel cold e.g photosynthesis
exothermic reactions are those that give out heat so if it is occurin in a beaker and u touch it u will feel heat.