Chemistry Definition and 993 Threads

Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant chemistry (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties of the soil on the moon (cosmochemistry), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics).
Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are two types of chemical bonds: 1. primary chemical bonds e.g covalent bonds, in which atoms share one or more electron(s); ionic bonds, in which an atom donates one or more electrons to another atom to produce ions (cations and anions); metallic bonds and 2. secondary chemical bonds e.g. hydrogen bonds; Van der Waals force bonds, ion-ion interaction, ion-dipole interaction etc.

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  1. onomatomanic

    Chemistry of traditional soapmaking

    I have two questions regarding the first stage of traditional soapmaking, which, according to a bunch of DIY websites, is to make "lye water" out of "hardwood ash". Firstly, the 'pedia article on "wood ash" says that "potassium hydroxide [aka potash lye] can be indirectly made from wood ash...
  2. E

    Most Rigorous General Chemistry Textbook

    I am seeking the most challenging and rigorous gen. chem. textbook to learn from. I have it pretty well narrowed to Oxtoby vs. Atkins. Caltech appears to use Oxtoby. Furthermore, the description for the Oxtoby book touts itself as "the most modern, rigorous, and chemically and mathematically...
  3. L

    Alevel paper 3 chemistry: titration vs collection of carbon dioxide over water

    Homework Statement titration method is more accurate than collection of carbon dioxide over water method to solve stoichiometry equation. Homework Equations what are the 3 reasons? The Attempt at a Solution some carbon dioxide has leak into the air, carbon dioxide is partially...
  4. C

    Identifying the Electrophile in But-2-ene and Bromine Reaction

    Homework Statement But-2-ene reacts with bromine in the presence of concentrated aqueous sodium nitrate to give the following compound CH3-C(H)(ONO2)-C(H)(Br)-CH3 Which of the following statement is correct. a.the electrophile is NO2+ b.Only 2,3-dibromobutane is formed. c.Resultant...
  5. A

    Programs Chemistry Major: Am I on track for Physical Chem?

    So I am a Chemistry major, but am behind on my math (was a Biology major but switched because I decided I would rather minor in Biology so as to avoid the boring plant and evolution/ecology stuff, plus I love Chemistry lol) and so am only taking calculus II this coming semester. My adviser wants...
  6. T

    AP Chemistry basic reaction problem

    Homework Statement Solutions of cobalt(II) nitrate and sodium hydroxide are mixed. What are the solubility rules for the hydroxides? and it occurs in a aqueous solution Homework Equations I have no idea how to solve these problems from my chem class lasty year and we will be...
  7. A

    A2 Physics Experiment: Electrical Conductance Through Salt Solution

    After summer I have to do my physics A2 experiment coursework. I really like working with electricity and looking at what happens at an atomic level, but I fear that what I want too do is more chemistry than physics. I had the idea of look at electrical conductance through a salt solution...
  8. J

    How to Find Ethanol %/Volume at 24 Degrees Celsius?

    Homework Statement Using the density of ethanol at 24 degrees Celsius how would I find the %/volume? I can find lots of places that have 20 or 25 degrees but I don't know where to find something referring to 24 degrees? Homework Equations The Attempt at a Solution I have to...
  9. T

    Chemistry Can a BS in chemistry do whatever a BS in physics does?

    I'm solely talking about recent grads in these two fields. The job market for chemists is pretty dismal; I'd imagine it's more true for physicists, is it not? But it seems to me the skills learned under these two degrees are quite similar...I mean any physics BS can work as a labrat and any...
  10. V

    Overlap between physical chemistry and chemical engineering?H

    How much overlap is there between physical chemistry and chemical engineering with regards to thermodynamics, kinetics, and transport phenomena? Would it be beneficial for a chemical engineering student to take the physical chemistry courses that deal with these topics? Or would it be redundant...
  11. B

    Chemistry Directions to go after a Master's in Chemistry

    Hi everyone, I am currently having a dilemma in regards to the next step of my education. I am into my second year of my MSc in inorganic chemistry and would like some advice in regards to different paths I could go after finishing. I've seen a lot of great advice given on this forum so I...
  12. H

    Applications of resonance in chemistry?

    While reading organic chemistry, the textbook said that resonance is something which is found everywhere in chemistry. It applies everywhere in chemistry and so on. However so far the only application I've found of resonance is that the more resonance structures a certain molecule has, the more...
  13. J

    A Textbook that combines biology, chemistry, and physics?

    Is there any textbook or any book (introductory, mostly) out there that combines the teaching of physics, biology, and chemistry phenomenon while appropriately teaching the details for each of the fields as it goes on. Or anything similar?
  14. D

    How Do You Calculate Kp and Qp for Chemical Reactions at Equilibrium?

    Hey guys, I've just got an assessment coming up. I just want to double check if I got it right and perhaps people can help me with a question or two. QUESTION 1. Consider the reaction A(s) + 3B(g) = 4C(g), ΔH°=-16.6kJ i) Given Kc = 0.00570, calculate Kp at 198°C. ii) Given p(B) = 0.10atm...
  15. I

    Chemistry Physics or Chemistry: Which Career Path to Choose?

    Hello everyone, just joined the forum. I need some solid advice about choosing my career path, I've read some of the previous posts on the topic, but would greatly appreciate any further help! I'm 18 years old, at the end of high school. I love and enjoy both Physics and Chemistry, and work...
  16. B

    Schools What's chemistry like in university? Lots of math?

    Hello, I am planning to major in chemistry and I just wanted to know if a lot of the material is, or requires, mathematics. I love math and I would say I am pretty good at it. It would be my second choice for a major. However, I heard that chemistry is not really a mathematical science, more...
  17. H

    Chemistry: Electron Configuration of Manganese Cation

    Homework Statement Write the ground state electron configuration of Mn2+. Homework Equations N/A The Attempt at a Solution Well I thought that since it had the 2+ superscript and manganese is a metal, it must have lost two electrons. Manganese has an atomic number of 25 and...
  18. M

    Oxidation & Reduction: Measurement of Power - Electrochemistry

    how oxidation or reduction potential a measure of oxidizing or reducing power,it just observed that higher r.p or o.p higher oxidizing power or reducing power,or it has well sounded explanation
  19. J

    How Do Coefficient Changes Affect Equilibrium Constants?

    Homework Statement The reaction below has a equilibrium constant of Kp = 2.26 x 10^4 at 298 K CO(g) + 2H2(g) <=>CH3OH(g) Calculate Kp for each of the reactions and predict whether reactants or products will be favored at equilibrium A. (1/2)CO(g) + H2(g) <=> (1/2)CH3OH(g) Homework...
  20. H

    Chemistry: How do I write an ionic equation for this reaction?

    Homework Statement I was doing this problem for HW online, that asks to write the ionic equation for a reaction, but I'm completely stuck. After using all my attempts (i.e., I can no longer submit the answer even if it is right, :frown: ) I still couldn't get the right answer. We've only...
  21. djh101

    Programs Which math classes should I take as a [physical] chemistry major?

    I am majoring in chemistry at UCLA with physical chemistry concentration (transferring as a junior next semester), intent on pursuing research in the field in the future. I would like to minor in mathematics (if a double major is not possible), but I'm having a hard time deciding what classes I...
  22. R

    Need Guidance in a Chemistry Related Project

    Hello, I am a student with a chemistry project. However, I am not quite sure what I would like to do the project on. I am fairly ignorant when it comes the recent findings and happenings of the chemistry world. Some of my areas of interest would be biochemical, nuclear, and energy related...
  23. A

    Entropy calculations involving integration (physical chemistry)

    This isn't a homework question per se, but more of a coursework question. Specifically, I'm a bit at a loss as to how to go about learning a particular section of the coursework for a physical chemistry (i.e. thermochemistry) class I am taking. The section in question is that pertaining to...
  24. A

    General Chemistry Book Recommendations

    Hi! I wonder if you could give me some general chemistry book recommendations. I have a modest background in Chemistry (I've read introductions equivalent to "Chemistry, the central science", "Chemistry" by Chang, "Concise inorganic chemistry" by Lee and "Organic chemstry" by Clayden - I've...
  25. T

    How Do You Calculate Theoretical Reaction Time in Enzyme Experiments?

    I'm doing an EEI on enzymes. I'm using catalase and hydrogen peroxide to produce oxygen. The oxygen is then collected into a measuring cylinder. My three variables are the concentration of catalase, concentration of hydrogen peroxide and the temperature of both. Increasing the concentration of...
  26. H

    Organic Chemistry Hantzch Synthesis

    Homework Statement http://img51.imageshack.us/img51/9563/chem3.png Homework Equations The Attempt at a Solution I know the answer has to be a or c because you need the ammonia to make this reaction happen but I don't know whether you would want to use 3-oxobutanenitrile or...
  27. N

    Understanding Nucleophilic and Electrophilic Attacks in Organic Chemistry

    How to see if there is a nucleophilic or electrophilic attack? Nucleophilic or electrophilic attack? What type of attack performs a) the water molecule in the attack with one of its free electron pairs? b) bromine molecule when in an attack with a double bond? Motivate! I think...
  28. V

    Is quantum chemistry more theory heavy compared to chemical engineering?

    I'm a chemical engineering major and I have to take one of these. Is QM more theory heavy or are they about the same in that regard? I am leaning more towards QM. my only exposure so far has been with the "modern physics" part of general physics
  29. E

    Schools Is Chemistry Required for Computer Science Engineering?

    hey...can anybody help me out...Im an IB student and I wanted to know whether chemistry is required for computer science engineering or not?
  30. N

    How Many Moles of Fe Ion Are in 5 mL of Fe(NO3)3 Solution?

    Homework Statement If you have 5 mL of Fe(NO3)3(aq) at a concentration of 0.200 mol/L How many moles of Fe ion do you have? The Attempt at a Solution Would it simply be (0.200) * (0.005) = answer or would you have to divide that answer by three since one Fe per three NO3...
  31. B

    Chemistry What can you do with a major in chemistry?

    Hello, I'm currently a high school student in grade 12 and I was wondering what one could do after majoring in chemistry. I am very interested in it, as well as math, physics, and bio. I want to know what kind of jobs chemistry majors can get and how common some of the jobs are (for example...
  32. C

    Merging Mech. Engineering & Chemistry for work in the Military Sectoror

    Hi there. I am currently a freshman Mechanical Engineering major. I'll try to keep things short. I have a vision for my future; I want to design body armor and personal protective equipment for the military/paramilitary. This interest has lead me to pursue Mechanical Engineering as a...
  33. W

    Analytical Chemistry UF: Comparing Wavelengths & Frequencies

    Question 20 from our final I just took (Analytical Chemistry UF). "You may recall that the wavelength of the sodium D1 line in vacuum is 589.7558nm. In air it becomes 589.5924nm. What is the difference in frequency for these two wavelengths." I said 0. All the other people did the...
  34. S

    IB Chemistry Extended Essay help

    Homework Statement For my IB extended essay I want to determine the quantity of salt in comercial popcorns, and analyze if this amount of salt consumption is bad for one's health. I've made my investigation, and read that the levels of salt in these popcorns are quite high, and in the long...
  35. L

    Translation on Inorganic Chemistry ()

    Hi! I am trying to translate a paper on inorganic chemistry from Spanish into English but, since I am not an English native speaker and my knowledge of chemistry is limited, I could definitely use some help in order to get everything right. With regard to the title of the paper (NC =...
  36. M

    Answer Enthalpy Change Atomisation Hydrazine: B 1720 kJ

    Homework Statement Hydrazine was used as a fuel for the Messerschmidt 163 rocket fighter in World War II and for the American Gemini and Apollo spacecraft . What is the enthalpy change of atomisation of 1 mol of gaseous hydrazine? A 550 kJ B 1720 kJ C 1970 kJ D 2554 kJ Use of the...
  37. K

    Is chemistry needed for astronomy/astrophysics

    I am currently doing my GCSEs at secondary school and will have to choose 4 subjects for my A levels, currently I am thinking physics, maths, further maths and history. I also want to be an astronomer/astrophysicist and have heard that chemistry can be useful for that. Would i need to take...
  38. T

    Chem major who hates Organic Chemistry?

    I am chem major currently taking organic chemistry. I am ashamed of admitting I hate organic chemistry. This is not even science. It seems to me though, it is a branch of engineering. You have stuff, you make new stuff. You increase your yield and figure out steps to synthesize something. I...
  39. J

    Can You Check My Answers to These Gas Law Problems?

    Hello. If somebody has time can you check my answers? Q1: A gas occupies a 2.0L container at 25°C and 2.0atm. If the volume of the container is halved and the temperature remains constant, what is the new pressure? P1V1 = P2V2 P2 = 2.00 atm x (2.00L / 1.00L) = 4.00 atm --- Q2: The...
  40. J

    Chemistry | Enthalpy Change Calculation for N2H4 Combustion

    Homework Statement hydrzine, N2H4 ia a liquid rocket feul. It reacts with oxygen to yeild nitrogen gas and water. N2H4 (l)+ O2 (g)--> N2 (g) + 2H2O (l) the reaction of 6.50g N2H4 evolves 126.2 kJ of heat. Calculate the enthalpy change per mole of hydrazine combusted I am having trouble...
  41. J

    Summer Programs for High Scholars in Physics & Chemistry

    What are some good summer programs for high scholars involving physics and chemistry? I'm currently a freshman, next year will be my sophomore year and I'm enrolled to Pre-AP Chem and Pre-AP Physics. I have a strong interest in Physics and Chem; also I'm looking to get into one of the more...
  42. N

    Practical, interesting chemistry book

    I have taken general chem 1&2 and orgo chem 1&2, but I honestly don't know how the chemistry I know relates or is used in anything. I can write page long synthesis and mechanisms, but I don't really know what I'm making, if it's safe, or if it's impossible. I only have one chemistry class left...
  43. B

    Social and (Maybe) Technical Issues in Organic Chemistry Lab

    Hi, this is my first post. I'm generally more of a blog/message board reader than a contributor, but there's really been something that has been eating away at me, making it difficult for me sleep at night. (Note: long post coming up) Last semester in Organic Chemistry I, I made a huge error...
  44. B

    Should I take Further Maths and/or Chemistry A levels?

    Hello, I am new to these forums. I am in Year 10 and have decided to take Physics and Maths at A level. However, I need to choose 2 more A levels and have considered Further Maths and Chemistry. I would like to take Chemistry because I love science! But I'm worried there will be too much...
  45. M

    Overcoming Math & Physics Struggles to Pursue a Career in Chemistry

    My passion is constantly learning new things about Chemistry, and science in general. I wanted to be a chemical engineer and a chemist when I was in grade 9 but now that I'm in grade 11 and researching about the career as a chemist-- I realize there aren't many job offers, and the pay is low...
  46. MacLaddy

    Chemistry Department Photo: What's Happening in the Picture?

    Ignoring the school, links, and overall blandness of this website; can somebody PLEASE explain to me what is happening in the picture to the left? http://www.slcc-science.org/chem/ :rolleyes:
  47. S

    Chemistry: A titration of ethylamine with HCl.

    Homework Statement For the titration of 50 mL of 0.150 M ethylamine (C2H5NH2), with 0.100 M HCl, find the pH : a) when 10 mL more of HCl has been added than is required b) when 75% of the required acid has been added Homework Equations Maybe Henderson Hasselbalch?: pH = pKa + log (base/acid)...
  48. B

    AS Practise Chemistry coursework question

    Homework Statement Write an equation in words to show relationship between mass concentration, molar concentration and molar mass and give a short explanation. Homework Equations I understand that the equation is: molar mass = Mass concentration/Molar concentration The Attempt at...
  49. G

    The single most interesting chemistry journal article I've read in 5 years

    Traceless protein labeling http://www.nature.com/nchembio/journal/v5/n5/abs/nchembio.157.html http://www.nature.com/nchembio/journal/v5/n5/full/nchembio0509-275.html If this procedure really does work as they say, what a really, really slick idea this group has come up with. Not only...
  50. G

    Is click chemistry really viable for in vivo applications?

    With the huge interest in click chemistry for in vivo applications--the staudinger ligation and the Huisgen cycloaddition, I was wondering, just how viable are these reactions in real world settings? Assuming second order kinetics, the fastest ever reported Staudinger ligation click reaction...
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