What is Chemical: Definition and 1000 Discussions

A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances, chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
Chemical substances exist as solids, liquids, gases, or plasma, and may change between these phases of matter with changes in temperature or pressure and time. Chemical substances may be combined or converted to others by means of chemical reactions.
Forms of energy, such as light and heat, are not matter, and are thus not "substances" in this regard.

View More On Wikipedia.org
Recent contents Top users
  1. E

    Arranging Chemical reactions into

    Metal AX BX CX DX EX A - + + + + B + - + - - C + + - + - D...
  2. K

    Chemical Bonding - Polar bonds

    What determines the ionic nature of a bond? I am a bit confused regarding this. Is it the polarising ability of the cation or the greater electronegativity of the anion? Regarding fajan's rules, smaller the size of the cation (and greater the charge) and smaller the size of the anion, greater...
  3. O

    Chemical and Bio-chemical Sensor

    I was trying to find some information regarding nanotube-embedded chemical and bio-chemical sensors and especially information comparing such sensors to classical capacitive sensors. For example, I need answers to such questions as how can capacitance be detected at the nanoscale? To what...
  4. S

    Machine Converts Chemical Energy To Electrical Energy?

    What Kind Of Machine Converts Chemical Energy To Electrical Energy? A)dynomite Explosion B)batteries Or Fuel Cells C)steam Turbine D)hydrogen Bomb Explosion E)tail Of A Firefly
  5. E

    Evidences of a Chemical Reaction

    Q: Can u tell me what are the evidences of a chemical reaction?
  6. A

    Energy is neither created nor destroyed in a chemical reactions.

    Energy is neither created nor destroyed in a chemical reactions. Explain where the energy released by the reactions comes from.
  7. A

    Chemical equation ammonium nitrate with water

    If i added ammonium nitrate with water, what is the chemical equation? is it NH4NO3 + WATER = NO2H + HNO3
  8. G

    Chemical charge the same as electrical?

    Are ions effected by electrical charge? If a positivly charged ion was placed near a postivley charged plate, would the ion be repelled?
  9. P

    Chem Rxn Help: Na_2SO_4 + Ba(NO_3)_2 -> BaSO_4 + NaNO_3

    I just needed help understanding the concept of this chemical reaction Na_2SO_4 (aq) + Ba(NO_3)_2 (aq) \rightarrow BaSO_4 (s) + 2NaNO_3 (aq) This is the conventional equation, and I wrote the net ionic form to be: SO_4^{2-} (aq) + Ba^{2+} (aq) \rightarrow BaSO_4 (s) However, the answer in...
  10. P

    Chemical Reaction Between HF and H2O2

    Can anyone tell me what's the reaction and product if I mix Hydrofluoric Acid (HF) and Hydrogen Peroxide (H2O2)? HF + H2O2 = :confused:
  11. R

    Chemical weapons loose in London?

    (http://today.reuters.com/news/newsArticle.aspx?type=topnews&storyid=2006-06-03T125413Z_01_L03352884_RTRUKOC_0_US-SECURITY-BRITAIN-SHOT.xml&WTmodLoc=NewsArt-R1-MostViewed-2) Either a very new threat has in fact materialized ( :eek: ), or certain sensationalist media are over-hyping an imagined...
  12. O

    Creating Chemical and Electromagnetic Energy

    I am supposed to make a machine that encompasses different types of energies. I just have no idea what I can do for chemical energy and electromagnetic energy using household materials, for the most part. I was thinking possibly using a match for the chemical energy. Would have a solar powered...
  13. W

    What do you think of http://www.webqc.org?

    Hello! Please evaluate my web portal http://www.webqc.org" and tell your opinion. Thank you in advance!
  14. S

    Chemical Equilibrium (answer check)

    Consider the following reaction A(g) <---> 2B(g) + C(g) When 1.00 mol of A is placed in a 4.00L container at temperature t, the concentration of C at equilibrium is 0.050 mol/L. What is the equilibrium constant for the reaction at temperature t? Here is my answer: The balanced...
  15. A

    The Chemical Basis of Industry

    "The Chemical Basis of Industry" Choose one of the industries listed below to research. automobile cleaning clothing manufacture computer construction cosmetic dental farming food preparation food processing fuel law enforcement medical photography software Your...
  16. R

    What is dynamic nature of chemical equilibrium?

    what is "dynamic nature" of chemical equilibrium? Explain what is meant by "dynamic nature" of chemical equilibrum?? thank you
  17. S

    Chemical asorb sun energy?high CO2 in atmosphere

    good day to everyone, i wish to ask what chemical in our environment asorb some energy from sun? and what it has to do with high C02 level in the atmosphere? thanks in advance
  18. A

    Precipitate will form in a chemical reaction?

    How can you predict weather or not a precipitate will form in a chemical reaction?
  19. A

    Is the Equation H2O2 + MnO2 = 2HO + Mn + O2 Balanced?

    Hi, I need help balancing this equation H2O2+MnO2=2HO+Mn+O2 is that right?
  20. S

    Very simple inorganic chemical reaction HELP

    Hello. Can you please help me with this reaction? * KBr + NaOH --> ?* Put KBr in boilling solution of NaOH. What are the products?
  21. V

    Chemical bonding - spin of bonded electrons

    Can anybody here please explain to me about the spin of an electron in the covalent bond? My textbook just says that it follows the Hund’s rule. Moreover I am confused with one more statement in the text – it says that in a covalent bond, in the bonding molecular orbital the electrons tend to...
  22. B

    Biology Science Fair: Seeking Research & Chemical Guidance

    I am doing a biology science fair. Here is my plan: I am going to ask my pharmacist for HCG containing pills, and put them into 5 different cups - one which will remain as a constant I can compare the others to. To the other four, I will add different chemicals, then test them for HCG using...
  23. M

    Some simple chemical reaction help

    Here is my first question. Cl2O + H2O -------> I am pretty sure this is a synthesis reaction becasue it there is non metal oxide and a water. I also know a non metal oxide plus a water forms an acid. I predict this to be HClO3. If that is the correct answer, I can't seem to balance...
  24. B

    Discover the Versatile Chemical with Changing Polarity | Find Help Here

    Is there a chemical that when heated its polarity changes?
  25. B

    Prospects of Chemical Engineering

    Hi I've recently applied for Chemical engineering at UMIST (Or Manchester university) to, in my mind at the moment, research properties of materials relating to its physical properties, and conductivity. So I would like to ask: What are the current main 'outstanding' problems in...
  26. E

    Can some one explain balacing chemical equations to me

    I don't understand how to balance equations. I have a huge test in science and i don't understand how do balance them. she says there is a easy short cut but she dosent want to to teach us it beacouse she thinks it will be to easy. could some one tell me a easy way or just explain how to do...
  27. S

    How Does a 10°C Temperature Increase Double the Rate of a Slow Reaction?

    We are currently studying reactions in terms of kinetic energy, reaction rates, collision theory, and so on. There is a question on my assignment that is kind of boggling me right now: An increase in temperature of 10 C rarely doubles the kinetic energy of particles, and hence the number...
  28. Hootenanny

    Is there a way to simplify my chemical system model?

    I'm doing a chemistry report and I'm attempting to model a chemical system. However, the formulae I'm coming up with looks rather ugly and complicated I was wondering if there was any way I could simplify it. I can't see any way though. I have come up with: SQ = \sqrt{\frac{CL^2 + 2CL +...
  29. H

    Chemical Bonding in Hydrocarbon

    While studying chemical bonding for methane,ethyne etc., I have made the following assumption to help me to remember the sigma bond, pai bond, and hybrid orbitals. 1. Every single covalent bond around a carbon atom is a sigma bond. 2. Only one of the bond in double and triple covalent bond...
  30. P

    Physical change chemical change?

    In chemistry class they talk about physical change as something changing that is easily seen by the naked eye and chemical change as something more fundalmental that is something changing such as Na and Cl combining to form salt which is way different to Na or Cl. But what happens if you...
  31. P

    Understanding the Chemical Reaction of CuSO4 + Fe and Its Effects on Iron Plate

    CuSO4(aq) + Fe(s) --> FeSO4(aq) + Cu(s) FeSO4(aq) + Cu(s) --> CuSO4(aq) + Fe(s) http://img106.imageshack.us/img106/6140/chem3fp.png Why does the iron plate becomes brown? I have no precise idea, but I think it might be related to the loss of electrons of the iron plate. Could someone...
  32. P

    What does a catalyst do in a chemical reaction?

    What does a catalyst in a chemical reaction? I read wikipedia and the information is not very detailed to satisfy me. It basically says:
  33. P

    Which are the products of this chemical reaction?

    Which are the products of this chemical reaction? (NH_4)_2Cr_2O_7(s)+ O_2 (g) --->
  34. P

    Is There a Better Way to Balance Chemical Equations Without Luck?

    Doesn't exist a method alternative to the one done by luck to balance chemical equations? The small equations are easy to balance by luck, but with the long ones I lost a lot of time. Thank you. :smile:
  35. M

    Identifying Unknown Gases and Liquids: Chemical Changes and Solutions Explained

    2. An unknown gas was burned in oxygen to produce nitrogen gas and water vapor. Was the unknown gas an element? Explain. 6. You are given two liquids. One is a pure compound, and the other is a solution. How could you distinguish the two liquids? These are not found in textbook. They...
  36. D

    What is the Main Chemical in Robitussin and Where is it Found?

    DM's either a chemical, or asa friend i know said an alcohol(?) whats its full name and is it found in acid? either acid or lsd
  37. J

    What is the difference between chemical engineering and chemistry?

    I've been really trying to grasp the differences between the two. Do Chemists mainly stay in labs and do quality controll/reasearch? While Chemical engineers put allready obtained knowledge into use? I'm really confused on this and can't decide which is more of the direction I'd like to...
  38. G

    How do you create chemical equation?

    How do you create chemical equation?
  39. A

    Help With Chemical Bonding Worksheet

    I just started a worksheet and wanted to check the answers I've gotten thus far and ask for a bit of help with the ones I'm stuck on.:smile: [What's bolded is my answer.] A chemical bond is an attractive force that holds atoms together. Chemical bonding is the process of atoms...
  40. C

    Where can I find chemical equations for Thorium?

    Anyone know where I could find a couple of chemical equations for Thorium. I need them for a project I am currently doing. I have not been able to find any.:uhh: Thank you.:smile:
  41. M

    Make a superhero with the chemical neon

    I need to make a superhero with the chemical neon and it should have stuff like physical qualities, chemical reactivity, how does it react with other elemts, what's it do, historical facts, neighbours in periodic table.. when was it discovered and by whom i was wondering if you guys could...
  42. G

    Change in chemical potential

    Consider a solution of particles of type A and B with the following Gibbs potential G(P,T,n_A,n_B)=n_A g_A(P,T) + n_B g_B(P,T)+ (1/2)\lambda_{AA}n_A^2/n + (1/2)\lambda_{BB}n_B^2/n + \lambda_{AB}n_A n_B/n + n_A RT \ln(x_A) + n_B RT \ln(x_B) where the n_i's are the number of moles with x_i=n_i/n...
  43. J

    Programs Chemical Engineer Major: Math vs Chemistry for Employment

    Hello all. I am currently in my first year of a chemical engineering program and I was talking to someone in the Chemical Engineering section of this forum and he said that partial differential equations is very important for Chem E's. He actually said that I should not even thing about...
  44. S

    News US forces use of Chemical weapons in Fallujah

    This video is graphic, not for those with a weak stomach. http://www.informationclearinghouse.info/article10907.htm
  45. G

    Medical Chemical and Electrical transmission

    Signal propagation along motor nerves or fibres of muscles is electrochemical (or electrical)l, whereas transmission at the neuromuscular junction is chemical, Why is that?
  46. S

    Identifying Unidentified Yellow Chemical in Tin Chloride

    Today I was making up some solutions of tin(II) chloride dihydrate (SnCl2.2H2O) and I noticed that an insoluble, yellow chemical had formed at the bottom of the beaker. I have no idea what this could be. I've thought about the possibility that there was an impurity in the tin chloride, but...
  47. A

    Finding the chemical equation

    My question is about finding the chemical equation and name of wrongly labeled element given the molecular weight of the formula and weights of two of the elements. The problem gives the overall molecual weight of the formula as 150 grams/mole. Then it says there is 1.00grams of chloriene in...
  48. A

    Courses Chemical Engineering Student needs opinions on course usefulness please.

    I can take one of the following 3 courses as a technical elective. I need to know which would be the most useful to me. My Math background: I have taken a year of Calculus, linear algebra, and diff eq (no partials.) Thermal Physics [text: Kittel "Thermal Physics"]...
  49. BasketDaN

    Exploring Diamond Colloid: The Most Energy Dense Chemical Fuel?

    Does anybody know much about, or know where I could find out about, diamond colloid? It is the most energy dense chemical fuel, correct? And if that is true, that would mean it can react to expend the most energy per ounce of any chemical reaction, right?
  50. H

    Oleic Acid: Chemical Formula and Uses

    What is the chemical formula for oleic acid?
Back
Top