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.

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  1. M

    Can Non-Metallic Triggers Be Used in Sodium Acetate Heat Packs?

    Does anybody have any idea of whether or not a non-metallic trigger could be used in sodium acetate heat packs. The crystalisation preocess in the packs is triggered by bending the metal disks inside them which causes heterogeneous nucleation. Are there any plastics which could work where...
  2. D

    Chemical Engineering Program Accreditation and Curriculum: Is it Worth the Wait?

    Hey. I've just finished my first year of uni, and it is almost time to enrol in next years units. I have been kicking up between chemical and mechanical engineering for the past year, but after much research, i think ill go with chemical and process engineering. I was reading about the...
  3. H

    Looking into chemical engineering

    Interesting website you got here, found it by accident... looks like lots of smart peoples around here, maybe I can get smarter if I stick around. Little about me, just a young dude looking into chemical engineering, renewable energy and stuff like that, seems like the "in" thing nowadays, maybe...
  4. Wellesley

    Schools Best Chemical Engineering Undergraduate Schools

    I'm curious about what people consider is the best ChemE school. What schools do employers like to see applicants come from? This list excludes MIT, Cal Tech and other premier schools that are already rather obvious. Thanks for all suggestions.
  5. B

    Fuel may be designated by the chemical formula C51 H105 S2 (OH)3

    Homework Statement A fuel may be deignated by the chemical formula C51 H105 S2 (OH)3 Write out the balance equation for complete combustion of this fuel. Homework Equations Cx Hy Oz Sn [(x) + (y/4)] o2 > xCo2 + (y/2) H2o The Attempt at a Solution The problem is that I...
  6. J

    Balancing Chemical Equation

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  7. M

    Solving Chemical Kinetics Homework for A, B, C & D

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  8. H

    Where Can I Find Affordable and High-Quality Chemical Vendors in the US?

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  9. D

    What is the chemical name for OI2?

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  10. D

    Mass Relationships In Chemical Reactions

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  11. F

    How do I calculate the length of a chemical bond?

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  12. E

    Shielding Effect and Chemical Shift

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  13. J

    Chemical reactions with ether?

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  14. J

    Solubility and chemical equations

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  15. G

    Chemical Equilibrium: AgCl + NaCl Effects

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  16. S

    An egg is fried in a skillet, a chemical or physical properties?

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  17. N

    Use of computers in chemical engineering

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  18. C

    Two repulsive/attractive forces that influence chemical bonds between two atoms

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  19. T

    I understanding how to read and write chemical formulas

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  20. A

    Chemistry Basics: Learn Chemical Nomenclature

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  21. R

    What is the Chemical equation of this?

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  22. V

    Arrhenius Equation - Chemical Kinetics

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  23. P

    Does Chemical Reactions Affect Mass?

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  24. A

    Needed: All information on chemical Eng.

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  25. M

    Courses Math courses for Chemical Physics?

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  26. D

    How Does Hydrogen Sulfide Affect pH and Precipitation in a Cu-Zn Solution?

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  27. W

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  28. B

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  29. Q

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  30. U

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  31. G01

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  32. O

    Navier Stokes with chemical reaction

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  33. MathematicalPhysicist

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  34. S

    Chemical Engineering Thermodynamics

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  35. U

    What is the meaning of chemical energy, in terms of first principles?

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  36. M

    Trivial question about chemical rxns

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  37. R

    Uncovering Citric Acid's Chemical Composition and pH

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  38. S

    Courses Intro course on different types of chemical families

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  39. H

    What is the value of Kc for this equilibrium reaction?

    Homework Statement A 1.0 dm3 reaction vessel contains initially 1.0 mol of N2O4(g) and 1.0 mol of NO2(g). At equilibrium, 0.75mol of N2O4(g) are present. What is the value of Kc? A. 0.33 B. 0.50 C. 2.0 D. 3.0 The Attempt at a Solution Right answer = D, but I do not why. My attempt...
  40. M

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  41. B

    Chemical form of uranium in a bomb?

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  42. M

    Solving the Kc of a Chemical Reaction with N2O4

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  43. C

    Chemical Equilibrium: Co(H2O)62+ + 4 Cl- ----> CoCl42- & 6 H2O

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  44. R

    How to determine the product of a Chemical Reaction.

    Ok the question is some what simple and difficult. I know there are certain rules like a. A + B = AB (combination) b. AB = A + B (decomposition) c. AB + C = CB + A (substitution) d. AB + CD = AD + CB (metathesis) now the trouble i have is not in balancing the equation but figuring out...
  45. S

    Chemical info needed to break ceramic tile

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  46. L

    Calculating Salicylic Acid Required for Aspirin Production

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  47. K

    Chemical Equation: Dissociating PbBr2 - Ksp of 6.3E-6

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  48. A

    Cat urine in pool chemical room

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  49. M

    Solve 3 Chemical Equilibrium Questions & Calculate Kc

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  50. R

    Chemical , Pericyclic Reaction

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