What are the differences between a physical change and a chemical change?
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A physical change would include changes that have to do with the physical aspects of the substance, such as: color, state of matter, or temperature. A chemical change occurs when a reaction takes place and a new substance is produced, like the reaction of sodium and chlorine to produce salt.
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if you go from A to be and then B to A you should have no overall energy change. one will be an exothermic reacion and the other should be endothermic reaction
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-Chemical reaction rates vary with conditions of the change, but nuclear rates do not.\nthis statement is true
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Burning is a chemical change. Oxygen reacts with the material that you burn and converts it into the corresponding oxide. You start with one chemical and end up with another in the burning process. In the case of boiling, a liquid is converted into gaseous (vapour) state. Here the material is same; only its physical form is different before and after boiling. Hence it is a physical change.
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It highly depends on what you're mixing.\n\nTypically, the good signs to look for are these:\nEvolution of Gas\nEvolution of Heat\nForming of Precipitate (two clear liquids become murky)\nChange of Color\n\nPretty much a change in any physical quality. If you want to figure out if a chemical reaction occurs without actually doing an expirement, look up "Reaction Spontenaity"
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n chemistry, a physical change is when a substance undergoes some form of change that does not change the substance at the molecular level (i.e. a chemical change). Physical changes do not create new substances, as in a chemical change, but result in the same substance in a different form or shape. A physical change in which a substance changes states between solid, liquid and gas is called a phase change. When water is frozen into ice it undergoes a phase change, and thus a physical change, as it is still water but in a different form. Under normal conditions physical changes can generally be considered reversible, however this does not always hold true. Other characteristics of physical changes include the absence of a newly created substance or the change is reversible.\n\nA chemical change is a process in which reactants are changed into one or more different products. A chemical change occurs whenever new compounds are formed or existing compounds decomposed. During this reaction, chemical bonds between atoms are broken and new chemical bonds formed. This results in a rearrangement of the chemical bonds.\n\nThere are several different types of chemical change. These include synthesis, decomposition, single displacement, double displacement, neutralization, precipitation and redox.\n\nIndicators of a chemical change include a colour change, the formation of a precipitate, the formation of gas, production of heat or light, the appearance of a new substance, a use-up of a starting substance, or exposure to the tertiary chooper enzyme or a change in temperature or energy. When new substances are formed, a chemical change has occurred, and a chemical reaction has taken place.
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Most of the processes are actually physical but still there are some chemical processes; most chemical processes are intermediate reactions to clean up a product or to add some chemical for enhancing specifications.
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A chemical property is a property of a substance that becomes apparent during a chemical reaction, and can only be observed by changing the substance's chemical identity.
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During a chemical reaction, existing bonds are broken, atoms are rearranged and new bonds are formed.
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A Chemical action means that a substance has reacted chemically on another which is in bulk. A chemical reaction is usually idependent of physical form.
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heat change\ncolor change\nemmission of gas
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Energy\n\nA chemical reaction simply supplies energy to the system
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A chemical reaction involves only the electrons of the atoms -- the nucleus of each atom remains unchanged.  In addition, the same number of the same types of atoms is present after the reaction as was present before the reaction.\n\nA nuclear reaction involves a change of the nucleus of the atom(s), either splitting one large nucleus into one or more smaller nuclei (fission) or joining multiple nuclei together to form a larger nucleus (fusion).  This means that after a nuclear reaction, there are a different number of different types of atoms than there were before the nuclear reaction.\n\nIn addition, nuclear reaction tends to produce large amounts of high-energy photons (x-rays, gamma rays, etc) and nuclear particles (alpha and beta particles) as a result of the reaction.  Chemical reactions produce low-energy photons (heat and visible light) and do not produce nuclear particles.\n\nIn a nuclear reaction, some of the matter of the original atom is converted into energy -- so the resulting products will have less mass than the total mass of all the original material.  In a chemical reaction, the mass always remains the same because the same number and type of atoms are still present.
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Physics, Chemistry and Biology.\n\nPhysics is the science of matter and energy and of interactions between the two, grouped in traditional fields such as acoustics, optics, mechanics, thermodynamics, and electromagnetism, as well as in modern extensions including atomic and nuclear physics, cryogenics, solid-state physics, particle physics, and plasma phyics.\n\nChemistry is the science of the composition, structure, properties, and reactions of matter, especially of atomic and molecular systems. \n\nBiology is the science of life and of living organisms, including their structure, function, growth, origin, evolution, and distribution. It includes botany and zoology and all their subdivisions.
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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.
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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.
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um...right...please retype the question. if you want to know more about the branches (inorganic, organic, physical etc) try www.chemistry.org