Chemical Definition and 1000 Threads

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. A

    Cat urine in pool chemical room

    Discovered that my cat has been urinating in my pool equipment room this winter. My equipment room is in my basement. We store all of our pool chemicals here. I am worried that the chlorine will mix with the urine and create a toxic gas. Could this happen? Sometimes when my husband refills...
  2. M

    Solve 3 Chemical Equilibrium Questions & Calculate Kc

    Hi, I have 3 questions i can't seem to solve anyways thanks in advance. 1) If the equilbrium constant at a cetain temperature is 24 for the reaction, 2NO(g) <-> N2(g) + 02(g). Both of the systems listed below cannon be in equilbrium because at this temperature because there is only one value...
  3. R

    How Do External Fields Influence Pericyclic and Thermal Reactions?

    1. What is the effect of external applied static electic/ magnetic field effect on pericyclic, thermal...etc type chemical reactions? 2. What is the direction of resulting dipole deuto the three dipole arrenged in trianguler geometry?
  4. S

    Chemical structure of Acetyl-Phosphate

    Acetyl phosphate is produced during acetate fermentation. I can't find the structure for it anywhere. The precursor in this case is Acetyl-CoA, which has the the structure H3CO-S-(Coenzyme A). And of course I know the structure of a phosphate ion. So the only question really is, does...
  5. R

    Which ∆H Should Be Used in Chemical Equations and Potential Energy Diagrams?

    So, I did 5 labs where I burned certain things and found the temp. diff. in the calorimeter. That said, I calculated the ∆H for the entire system, the ∆H per gram of system substance, and the ∆H per mol of system substance. Im wondering which ∆H I should be putting into my chemical...
  6. J

    Balancing Chemical Reactions: Isobutyric Acid + 2-Methoxyethanol

    hi i have the following reaction isobutyric acid + 2-methoxyethanol <-> 2-methoxyethyl-2-methylpropanoate but i don't know all of the by-products. please help thanks edit: i think is only water and some unreacted reactants?
  7. M

    Program for chemical model and formula

    Is there a program that can make a chemical model for you if you write the chemical formula or the other way around?
  8. A

    Florida Insititute of Technology Chemical Engineering

    I'm about 70% certain of going to this university in order to do my chemical engineering course. Is there anyone who's been to the university, or knows anyone who has been and can tell me what the institution is like, how much work they had to do to get through and any other things which might...
  9. I

    Chemical Potential in a Degenerate Fermi Gas

    in a Fermi gas, we know that when the temperature is much less than the Fermi energy, it becomes a degenerate gas. does this mean the chemical potential of the system be very large?
  10. B

    Stoichiometry applied to reactions and chemical equations

    Homework Statement I don't understand this problem, i think he wants me to find the limeted reaction. If you could explain as good as possible. Thanks :smile:Homework Equations Al(OH)3(s) + H2SO4(l) → Al2(SO4)3(aq) + H2O(l) If 1.28 g of aluminum hydroxide reacts with 3.73 g of sulfuric acid...
  11. C

    Chemical equilibrium: Enthelpies and equilibrium contsants

    Homework Statement For the system 2 CO2 = 2 CO + O2, ∆H= 510 kJ the percentage decomposition of CO2 changes w/ temperature as follows. Temp, K...% Decomposition 1500...0.048 2500...17.6 3000...54.8 Calculate the equilibrium constants, plot lnK vs. 1/T. In the graph, find the slope and...
  12. L

    Chemical equation for Al + nitric acid?

    Alluminium + Nitric Acid = Alluminiumnitrate Whats the chemical formula for this equation ? :) Thanks
  13. S

    What is Diesel Fuel's Chemical Formula?

    hello, my name is Jesse and I'm new to the forums. I'm in 10th grade chemistry and i have a question. what is the chemical formula of diesel fuel? i searched it on google and found something about hydrocarbon and i have no idea what this is. please help
  14. D

    Calculating masses of reactants&products in chemical reactions

    i can't do this home work. i REALLY suck at physics, this is why I am here. can someone help me pleasse? :) 1#to combust completely 7g of iron, 2L of oxygen is needed. for each of the following state if any unreacred iron rests after combustion and if it does how much: a) 2g of iron and...
  15. E

    Is My Chemical Equation for Fuel-Rich Ethylene Combustion Correct?

    Homework Statement An engine is operated slightly fuel rich (phi>1). Ethylene (C2H4) and inert nitrogen (N2) are the reactants and there are 40 mol of nitrogen for every mol of ethylene. The hydrocarbons are burned over a catalyst and converted to carbon dioxide (CO2) and water vapor (H20)...
  16. S

    Chemical Equilibria: Law of Mass Action & Beyond

    chemical equilibrium law is made using the fundamental rule rate of forward reaction=rate of backward reaction and then applied law of mass action to it but law of mass action is not always correct in giving relation for the rate . so why it is used there? secondly if...
  17. S

    Chemical vs Aerospace Engineering

    Urgent Advice! Hey guys and gals, I have recently been accepted into the University of Melbourne in their new generation science course and finished enrolment yesterday... only now i can't decide what i want to do with it and i need to decide pretty quicksmart. I've started threads along...
  18. R

    Need Advice on Chemical & Engineering Majors

    please guide me...urgent -------------------------------------------------------------------------------- i just read the thread abt difference in chemists and chem engnr... thre waz a very gud reply from mr jacone... i m also confused in 1 thing... m studing in new york ... here in my...
  19. K

    Chemical Kinetics - Rate Laws and Mechanisms

    Homework Statement This is straight off an old AP Exam, but I can't seem to find it online so I'm hoping you all can help me out. 2 NO(g) + Br2(g) --> 2 NOBr(g) The following results were obtained in experiments designed to study the rate of the reaction above. Experiment Initial...
  20. R

    Reaction of CuSO4·5H2O & SrCl2·6H2O with Water

    ok what is the reaction of copper(2) sulfate penta hydrate and distilled water as well strontium chloride hexahydrate and distilled water.:cool:
  21. R

    General Chemistry - Chemical Equilibria

    General Chemistry -- Chemical Equilibria Suppose 1.22 atm of CH4(g), 2.57 atm of C2H6(g), and 15.00 atm of O2(g) are placed in a flask at a given temperature. The reactions are given below. CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g) KP = 1.0x10^4 2 C2H6(g) + 7 O2(g) 4 CO2(g) + 6 H2O(g) KP = 1.0x10^8...
  22. S

    Effect of accel/velocity on chemical reactions

    A simple question really. Does acceleration affect the rate of a chemicall reaction. I.e if I was to put some test (chemical) experiment aboard a suitable craft and accelerate it to a high velocity, would the reaction occur at the same rate as it would at rest - ignoring relativistic effects...
  23. L

    New Develtopments In Chemical Engineering

    Need some help here. I'm going for an interview for Chemical Engineering and I'd like to get some detailed info on what's happening in Chemical Engineering. I've looked at Chem Eng journals for developments and here's where the problem is. I have to subscribe since I'm not actually an...
  24. turbo

    Managing Chemical Sensitivity & ER Visit

    True. I managed to drive myself to the hospital after being exposed to fragrances at work, and the triage nurse just waved me in based on my appearance. The intake nurse clocked my BP at 208/80 and shoved me into the ER. The ER nurse assigned to me was a classmate of my wife and contacted...
  25. S

    Chemical Reaction between water and chlorine

    [SOLVED] Chemical Reaction between water and chlorine Homework Statement Whats the reaction between chlorine and waterHomework Equations NoneThe Attempt at a Solution Is it the reversible reaction: Cl2(g) + H2O(l) <----> HCl(aq) + HClO(aq)
  26. V

    A chemical engineering example for lagurre equation

    Is there anybody here can give me a chemical engineering example that the final differential equation will be LAGUERRE ?
  27. S

    Solving Chemical Reactions: Helium, Hydrogen & Displacement

    Pls solve my problem quickly as i am junior, i am not expert in solving these: SiO2 + Na2CO3=Na2SiO3 +CO2 So how do CO2 get separated from products,and where did the 1 oxygen atom go, Is this equation needed to be balanced. Why is helium placed in the group of noble gases? Do it reacts...
  28. S

    Chemical Equilibrium Characteristics

    Consider the reaction: H2O(g) + CO(g) H2(g) + CO2(g) Which of the following statements are true and which are false. false Reactions with large equilibrium constants are always slow. false When Q > K the system will spontaneously shift to the right. false Amounts of all...
  29. D

    Chemical Engineering: Benefits of Double Degree & Further Study

    Hey. There are currently two degrees i am strongly considering taking next year, and chemical engineering is one of them. Reasons for my choice: I love maths I like chemistry Physics is alright =P The income is decent Now, if i did go for this, id make it a double degree and also do a...
  30. J

    Chemical rxns in a typical automoblie lead-acid battery.

    A typical automoblie engine uses a lead-acid battery. During discharge, the following chemical reaction takes place. Pb [sub](s)[sub] +PbO[sub]2[sub] [sub](s)[sub] +2H[sub]2[sub]SO[sub]4[sub] [sub](aq)[sub] +2H[sub]2[sub]O[sub]2[sub] [sub](l)[sub] (1) Pb [sub](s)[sub] +PbO[sub]2[sub]...
  31. hagopbul

    DPPH (a chemical salt [(C6H5)2N-NC6H2 (NO2)3]) and EPR/ESR

    I am doing this test on DPPH (a chemical salt [(C6H5)2N-NC6H2 (NO2)3]) The goal of the experiment is to study The Electron Paramagnetic Resonance or The Electron Spin Resonance Buy using this way: see it in the file
  32. H

    New, and with gas to liquid chemical

    Hello, I was led here when I did a search on "Chloramines". This is what has happened. I moved into an apartment. I was cleaning off my stove with Joy dish soap and a scrubby sponge, and tap water. I kept getting a really strong bleach smell. I found out the maintence used a product...
  33. P

    How Do You Calculate the Molarity of Chemical Solutions?

    This is probably an incredibly easy one for you, but it's frying me. I'm in AP Chem, and since I'm involved in a lot (excuses, excuses...tsk tsk...), my brain is fried and it's having trouble clicking. My teacher is unhelpful, even hostile, and the book provides no explanations. For example...
  34. K

    Chemical name for 12 protons and 10 electrons?

    What would the chemical name for 12 protons and 10 electrons? This has been bugging me forever!
  35. A

    Schools Good University for Chemical Engineering

    I'm a Caribbean student in my final year of high school and want to go to a University in the United States. Could anyone give me an idea of how good the engineering programs, notably chemical are at these schools: Florida Institute of Technology Howard University Georgia Institute of...
  36. P

    Calculating Charge Flows in Chemical Cells: How Much Zinc Reacts per Second?

    Hi there! Could anyone help me out with this question? Which steps should I take in solving this question? Chemical cells can produce quite large charge flows for substantial times before their chemicals have all reacted. If zinc is the metal losing electrons under chemical attack, what mass...
  37. B

    Thermodynamics chemical reaction problem

    Homework Statement What are q and w (in kJ) for the reaction of 22 g of Na(s) and 82 g of Cl2(g) to produce NaCl at 1 atm and 298 K. Homework Equations w=-delta(n(g))* R*T where delta(n(g)) = the moles of gas created during the reaction The Attempt at a Solution First, I wrote...
  38. rocomath

    Chemical bonding, is this book good?

    So I'm having trouble grasping the theories of Chemical bonding and I'm taking Organic Chemistry. I know it's not realistic that I will truly understand it, but I'd like some grasp of it. This book is written by Linus Pauling and I know he is a 2-time Nobel Prize winner, but is this book at my...
  39. P

    Cs2Se + Sc Reaction: Resultant Chemical

    I guess straight forward enough question, what would be the resultant chemical if Cs2Se + Sc = ?
  40. A

    Calc Mass Propane Needed to Raise Air Temp by 50K

    1. Homework Statement The standard enthalpy change of combustion of propane (C3H8) is -2220kJ/mol. It requires 1.0J of energy to raise the temperature of 1.0g of air by 1.0K. Calculate what mass of propane needs to be burned to raise the temperature of the air in the balloon by 50K. 2...
  41. H

    Solve Equilibrium for Chemical Reaction: 2A <-> B + C

    Homework Statement The following reaction initially contains [A]o = 0.2150 M and [B]o = [C]o = 0.4150 M. If the equilibrium constant for the reaction is Keq = 2.03, what are the concentrations of reactants and products when the reaction has achieved equilibrium? What is the value of deltaG for...
  42. M

    Nuclear reaction or chemical reaction

    If you light a match to a mixture of oxygen and hydrogen which then reacts explosively to form water. Is it a chemical or nuclear reaction? I know a chemical reaction is one in which a substance is changed into one or more new substances. A nuclear reaction is one in which a new element...
  43. M

    Do Nuclear Reactions Create New Elements?

    In chemical reactions the individual elements present in the reactants are the same as in the products of the reaction. Is this true for nuclear reaction? My attempt Nuclear reactants produce new products, and a new element can be made. This means that a new element with different proton and...
  44. M

    Chemical element and chemical property

    Is it possible for atoms of the same chemical element to have different chemical properties? My attempt Isotopes of an element differ from one another by the number of neutrons in the nucleus. They have same number of proton in the nuclei so they have the same chemical properties but not...
  45. chemisttree

    Illegal/Dangerous chemical activities

    Illegal/Dangerous Activities: Explicit "how to" discussions of illegal and/or dangerous activities, or posts advocating such activities, are prohibited; such as: how to make explosives, manufacture crack, steal software, hack into the CIA, ... The Physics Forum’s guidelines regarding...
  46. J

    Chemical versus nuclear reaction in charcoal

    From my experience one cannot under go a nuclear reaction of a material by heat alone, so why does charcoal, which all i have heard is carbon, yeild potassium and sodium compounds when heated? :mad:
  47. K

    Chemical Equations for Alpha, Beta & Gamma Radiation

    Homework Statement chemical equation for a) alpha decay of radon-222 b) beta decay of Na-24 c) gamma radiation of tritium Homework Equations The Attempt at a Solution 3 1 0 Gamma RADIATION H ----------- n +...
  48. K

    How to Write Proper Chemical Designations for Isotopes?

    Homework Statement write the "proper chemical designation" for the following isotopes a. uranium-238 b. carbon-14 c.polonium-210 Homework Equations The Attempt at a Solution would i just state number of protons, electrons and neutrons uranium-238...
  49. K

    Solving Chemical Equations for Alpha, Beta, Gamma Decay

    Homework Statement chemical equation for a) alpha decay of radon-222 b) beta decay of Na-24 c) gamma radiation of tritium Homework Equations dont know The Attempt at a Solution can someone write down the equation
  50. M

    Does Mixing 2-Propanone and 2-Ethylhexanol Create C11 H24 O2?

    If I add the chemicals C3 H6 O (2-propanone) and C8 H18 O (2-ethylhexanol) will I wind up with the chemical formula C11 H24 O2 ? thanks
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