What is a physical and chemical change? Explain your answer.?
488684
a physical change is changing the appearance of something... like if you melt ice, techincally it's still ice, just in a different form... you can ALWAYS change something back when you change it physcially\n\na chemical change is just the opposite. its cahnging the chemical balances of something and you can't change it back... like if you burn wood... the wood turns to ask and you can never get that ash back into wood.
862924
Remember the defintions of "chemical" and "physical" properties!\n\nPhysical are those that can be experienced by the senses (sight, smell, taste, hearing, touch). Chemical are those in which the chemical reaction creates a new material; however, it has become accepted practice to use "chemical property" to define a material's behavior at a set of known conditions (temperature, humidty, pressure, etc). \n\nThe site given lists just about everything you'd want to know about Nitrogen; from it, you should be able to answer some of the basic "physical" characteristics and pull what you need for the chemical ones.\n\nLike I've answered before - since the definition of "chemical" has evolved over the years, you need to decide for yourself which ones best answer your query.
730330
Different chemical composition, one has a reaction the other doesn't..☺
585728
I have a question for you: WHAT THE HECK DOES THIS HAVE TO DO WITH CHEMISTRY?
645993
Exact chemical process...?\nNo one has yet discovered it completely\nBut they definetely are inching towards that secret...\nNevertheless what they so far have discoverd or will discover in future is only the chemical changes that happens 'when you love' but what I feel is more elusive is a question of 'what is this Love that makes these chemical changes in brain'...
673308
sucking on pasta is a chemical change, boiling it in water is a purely physical change though...
211484
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.
232711
Change in enthalpy (or "heat content").  Enthalpy is defined as the internal energy plus the pressure of the system times the volume, or, in other terms, H = U + PV.\n\nChange in enthalpy is the change in heat content resulting from a chemical reaction.
233794
Historically Chemistry was broke down into two areas - organic and inorganic.  The inorganic chemists, those who dealt with non living matter were called physical chemists because they spend their time analyzing the physical properties of matter. What we talking of here is areas such as thermodynamics and quantum mechanics and making nuclear bombs.  Then  in the late 40's physicists enter the arena, a la Watson and Crick, and the difference between organic, inorganic and physical blurred to the point of disappearing.  These days a typical physical chemist works for industry doing spectographic analysis of whatever the company product line is.  It may not be sexy, but quality control is important and someone's got to do it.
270794
Melting means a change of physical phase.  There are essentially three phases of matter here on earth: solid, liquid or gas.  When a solid substance becomes liquid, that is said to "melt".  The opposite of melting is freezing, or going from liquid to solid phase.\n\nShrinking means reduction in size or length.  The chemical bonds are altered; the phase remains the same (which is most often solid).\n\nShrinking does not involve change of phase whereas melting does involve change of phase.
915926
just cutting the hair is a physical change\n\ndyeing the hair is a chemical change\n\nhope this helps!
795875
A physical change is when a substance undergoes a change in form, but is still the same chemical composition. Some examples of physical changes include change of state (liquid water to steam), size (cutting paper in half), shape (folding paper), dissolving (ice tea crystals in water), and mixing (red and white paint). In any of the above situations, the chemical make up of the original stays the same. (Eg. liquid water is the same as steam or ice).
733335
Yes it is a chemical reaction, aka  chemical change. Carbon dioxide and water are combined with light energy to form glucose( a type of sugar ) and oxygen.  You end up with different substances than you begin with, therefore it's a chemical change
1022281
d)  both a and c\n\nbecasue in a chemical reaction   everythin on the product and teh reactant must be the same\n\nthe mass and atoms must be same
117720
Essentially pH is important in how reactions happen, and in a system as precise as the human body, any small change can have an effect on how the chemical reactions occur.  Enzymes might not work anymore, your blood cells might not be able to get as much oxygen, etc.
323999
Physical changes only change the appearance of the substance eg - water turns to ice or turns to water vapor is a physical change. The atoms are not rearranged. This kind of reaction is easy to reverse.\nChemical changes actually changes the chemical substance, and its characteristics and require much energy to occur. eg - hydrogen and oxygen combine to form water (H2O). these reactions are very hard to reverse. The atoms are rearranged. \nMarina.
761935
when in a chemical reaction