Please answer quickly !!!: What is a physical change and what is a chemical change ?!?
922983
lol chem... anyway a physical change is one that only effects apperence such as a paper ripping or adding paint to a wall. a chemical change changes what something is compleatly like burning paper changes it into ash
226110
There is confusion here between references to a chemical compound and a physical state. The chemical name given to the combination H2O is water. This is completely separate from the physical states it can take of solid, liquid or gas. Even when solid, the chemical compound is still water. In our lives water is vital and we interact with it in all of its physical forms. It is only sensible that our language would have different names for this important material as a solid (ice), a liquid (water) and a gas (steam/water vapor). I am sure these distinctions already existed before humans really understood that all three were the same material. So in everyday language we call solid water ice. To a scientist it is the chemical water in a solid form. Scientist might refer to other materials that are not usually in the solid state as ices so it might be necessary to clarify that it is water ice and not, for instance, nitrogen ice.
208346
Strictly speaking, a chemical change occurs when the bonds between atoms are either made or broken (often both).  Bonds can be either covalent (electrons are shared), ionic (one or more electrons are given up by one or more atoms and given to another atom or atoms), or metallic.  Burning something is a chemical reaction.
764428
For chemical changes, the energy scale is related to Boltzmann's constant, which is pretty small, and temperature, which is typically 1-1000 degrees.  For nuclear changes the energy scale is related to Einstein's famous equation, E=mC^2.  the mass is typically very small, say the mass of an electron, but the speed of light is huge, and gets squared, making nuclear changes much, much more energetic than chemical changes.  That's why the sun is billions of degrees, and a campfire is only thousands of degrees.
255271
Yes you are correct.Different substances are different because of  their molecular structure and the constituents of each molecule. Molecules are well bound together in solids than in fluids (gases and liquids). The molecules are free in gases.\n Further the molecules are not at rest and are in vibrations.When the substance is heated  the average energy of a molecule  increases which tend to decrease the bindings of the molecules.\nGenerally by heating , a substance  chnges from solid to liquid and then to gaseous state.We call this as physical change.\nWhen the energy is  strong enough to break the  molecules into its constituent elements new compounds are produced we call it as chemical change.\nIn effect heat  has many things to do with their bondings
865842
Energy\n\nA chemical reaction simply supplies energy to the system
499302
melting physical\nrusting chemical\nburning chemical
915926
just cutting the hair is a physical change\n\ndyeing the hair is a chemical change\n\nhope this helps!
751958
heat change\ncolor change\nemmission of gas
578226
A chemical change is one that produces one or more new substances with different properties from those of the starting materials.\nA physical change is which the chemical composition of the starting material does not change and no new substance is formed.
871372
Physical\n\nA chemical change is a change in molecular composition. For example: When you mix baking soda and vinegar, it ceases to be simply soda and vinegar. A chemical reaction takes place.\n\nA physical change is a change in physical property. For example: The irons heating element is activated, causing the metal to warm up. It doesn't change to any other form of metal, nor does its structure differ afterwards. It mearly changes in physical temperature.
950214
physical changes do not change the electron structure of a substance while a chemical change makes something totally new
66886
GO to wikipedia.com and type in chemical reaction.  That is kind of a tough definition, so I will help to break it down a little for you.  Basically, you got something, and it changes into a whole new a different thing.  That is a chemical reaction.  It could be 2 things coming together to make 1 thing, or vice versa.  Or two things could lead to 2 new things.  The most important part of a chemical reaction is that substances change to NEW substances that have serperate properties and characteristics from the original.\nOn wikipedia there is a link to an IUPAC definition.  IUPAC is pretty much in charge of defining stuff in chemistry, so their definition is the one you're looking for, however, it might be a little complicated.  If this didn't help, maybe you should repost your question.
290614
chemical reaction\n\nall substance give off some heat during change\n\nlook up kinetics on the web
252753
Changes that don't involve chemical reaction. Example: chenge in state (solid, liquid, gas), temperature change, etc. Ofcourse temperature change will initiate density change.. density is another physical property.
895819
Chemical. Because the way everything reacts to make you taste things. Thats why different things have different tastes. A physical property would be touch cause thats how it feels and theres no reactions taking place.
585728
I have a question for you: WHAT THE HECK DOES THIS HAVE TO DO WITH CHEMISTRY?