Chemistry Definition and 993 Threads

Strongest bond in chemistry ionic ,covalent or metallic?Bond strength decrease in the following order covalent > ionic > metallic so i think strongest bond would be covalent bonding then comes ionic bonding and at last metallic bonding.Correct me if i am wrong.One more question is water/ice...

Homework Statement The rate of the reaction was studied at a certain temperature. O(g) + NO2(g) --> NO(g) + O2(g) In the first set of experiments, NO2 was in large excess, at a concentration of 1.0 * 10^ 13 molecules/cm3 with the following data collected. time (s) [O] (atoms/cm3) 0...

Homework Statement Problem: I am told that the first mechanism is operative in saponification. The Attempt at a Solution However, this strikes me as wrong because the first mechanism involves the formation of dianion. Using hydroxide ion to abstract a proton and make that particular...

I was wondering, if ethanol is used in a food, as it commonly is with food flavorings (as a solvent), and that food is then dried out such that It is made into a powder or cereal or something, does all the ethanol completely evaporate? I know ethanol is very volatile and has a low boiling...

Homework Statement The dissociation constant Ka for the acid-base reaction HA-->(H+)+(A-) is given by Ka = products / reactants; but instead of listing Ka, people generally list pKa = -logKa (where log indicates the 10-base logarithm). Similarly, instead of using [H+], people generally use pH...

I've read an article about computational chemistry in which the authors were performing a geometry optimization. For this purpose, they firstly optimized the geometry at HF/6-311++G(d,p) level with full relaxation on the potentiel energy surface (what does that mean exactly ? Can we extract this...

I majored in materials science and engineering, but my primary interest seems to be more in the chemistry aspect of materials, so I've been thinking about going into chemistry as well. I've taken chemistry courses (up to organic chemistry and orgo lab) but did not major in it. For chemistry PhD...

Homework Statement I'm taking an online introductory chem course, and while explaing the failure of classical mechanics to describe electron behavior, the teacher brought up the following ode which is based on Newton's second law and coulombs law: -e^2/4(pi)(epsilon-nuaght)r^2=m(d^2r/dt^2)...

Hello, I have questions. I love science. I don't think I am much of a biology person so naturally I am more appealed to both chemistry and physics. While I find physics incredibly fascinating and logical, I am exceedingly mediocre at the subject, earning only B's on all of the quizzes and...

Homework Statement How much energy is required to decompose 765 g of PCl3, according to the reaction below? The molar mass of PCl3 is 137.32 g/mol and may be useful. 4 PCl3(g) → P4(s) + 6 Cl2(g) ΔH°rxn = +1207 kJ The Attempt at a Solution 765 g PCl3 x 4 mol PCl3/137.32 g PCl3 = 22.28 mol...

Hello! I understand that a lot of this may be considered physics, but It is for AP Chemistry. We will likely be required to identify a certain element on the periodic table given a set of quantum numbers of one of its electrons. I understand the primary quantum number, n, essentially...

im only 17 and have recently joined an honors chemistry class and i found that people are trying to make new elements. now i have already heard about this before but recently i have been interested. i don't know if this has been tried before i don't know but i was wondering if you take element...

What is the degrees of freedom at the critical point of a 1 component system such as water. in my test I put zero because the critical point is a POINT that is fixed per substance. is there any books that can back me up? I heard that my teacher said there was 1 degree of freedom which I am...

After 20 years of being a locksmith, I have decided that I want to get a college degree and I'll be starting next year! As part of my degree, I will be doing two chemistry courses which will cover: - Intermolecular forces, chemical equilibrium, energy considerations and chemical reactivity...

1. Suppose that you have a sample of a gas in a cylinder equipped with a piston that has a volume of 1.50 L, a pressure of 1.20 atm, and a temperature of 250 K. Suppose that the gas is expanded reversibility under isothermal conditions until the pressure is 0.75 atm. What is the entropy change...

Hey all, I want to preface this with I wasn't sure if I should put this in the physics thread since it is quantum mechanics or in chemistry thread since this is for my Physical Chemistry course. I will gladly move the thread if the community feels it is more appropriate in the physics thread. I...

Homework Statement For the reaction: 2SO3(g) →2SO2(g)+O2(g) when 2.00 mol of SO3 is added to a flask at 10.0 L and 350 K at fixed volume, at equilibrium the ratio of SO2:SO3 is 0.663. What is the values of the equilibrium constant? What is ΔG° at this temperature? Homework Equations...

Homework Statement Here is the question: What weight of neutral red (molecular weight 289) must be dissolved in 1.00 ml to give a =40.0 µM (µmol l-1) solution? Give your answer in MICROGRAMS (µg). Homework Equations Not sure the only one I'm aware of is mole concentration (mol dm^-3) =...

Hi all, I'm new around here but I've checked out the site several times, thought it might be a good place to get some feedback. I graduated from the University of Georgia with a BS Chem in 2013, and have spent the last year working in sales. I'm now situated in Lubbock, TX (where Texas Tech is...

Consider the following generic equilibrium: aM + bN ⇌ cO + dP An equilibrium constant, K, can be defined as: $$K = \frac{[O]^c [P]^d}{[M]^a [N]^b}$$ But couldn't we also define another equilibrium constant similarly with coefficients that are in the same ratio as our original equation? For...

Hello! I have a few conceptual questions regarding thermochemistry. In thermochemistry, why is Q of solution equal to negative Q of reaction? Why is a volume decrease equal a POSITIVE value for w?

Homework Statement Calculate what mass of oxygen is required to completely combust 500.0g of gasoline. Assume that the gasoline contains only octane.[/B]Homework Equations My problem is... I don't know WHEN to apply sig figs. If this is a multi-step problem (i to iv in this case), do I apply...

I propose the Pauling Scale is not valid in all circumstances, and other scales of electronegativity would do better to predict the behavior of electron density in molecules: Electronegativity seems to be poorly defined for such a widely used chemical property: a 'tendency' of an atom or...

Here in Spain all of them are independent subjects at university and last year of high school, but in the first years of high school the contents related with physics and chemistry are joined in the same subject. The same happens with biology and geology. Therefore, high school physics teachers...

Homework Statement A 34.05 gram liquid sample of an unstable compound is deposited in a metal piston assembly that has a cylinder with a diameter of 20.0 cm. After the sample is added, the piston is placed in contact with the liquid and the piston vent is closed. This process removes all...

Hello! I need a little help! At school we did an experiment. We took cooper sulphate (CuSO4.5H2O) and heated it.Then we tried to see whether there are five moles of water to each mole of cooper sulphate. I am asked to "start with a brief statement of how the experiment allowed you to determine...

So, I want to write a paper for this year's science fair. I wanted to ask, if anyone could give me a few suggestions on some cool topics? It doesn't necessarily have to be Chemistry, it could be Physics, Mathematics, Bio, etc. If anyone has some ideas about Food Chemistry, that'd be cool too...

Homework Statement Given the functions Q(v,w) and R(v,w) [/B] K = v(dQ/dv)r and L = v(dQ/dv)w Show that (1/v)K = (1/v)L + (dQ/dw)v (dW/dv)r I have the problem attached if for clarity of the information. Homework Equations I assume everything is given in the problem. The Attempt at...

So I just started learning about enthalpy changes and all the equations that go along with it (for grade 12 chem). I wasn't sure how to do a few questions, so I'd really appreciate the help. I'm mostly kinda confused on when to use the equations q = mcdeltaH and deltaH = ndeltaHx 1) If at 25°C...

Hey there folks! I'm a math/computer science major focusing on scientific computing and I was wondering what courses I would need to take in my undergrad to be able to help out in Computational/Theoretical Chemistry. I've taken general chem and taking P Chem soon, is this enough or are there...

Hi what would be some good books for helping to understand chemistry for beginners? I'm not sure what kind of level of understanding this forum is aimed at or if it is (or can be) made to accommodate people who have very limited understanding of science. Unfortunately I didn't take science...

Homework Statement A silicon chip used in an integrated circuit of a computer has a mass of 4.86 mg. How many silicon atoms are present in this chip? Homework Equations no. of moles of element = no. of particles / 6.22 * 10^23 particles No. of moles of a element : mass of element...

Hello everyone I'm coming here to ask for some career advice. I graduated last year with my degree in accounting and I'm really at a point that I just hate it and am getting out of the field completely. I was originally studying to be a teacher for history and art however because of the...

Hello, I was wondering if anyone could help to explain something simple to me, I am lost for answers, and this is something a 7th grader should know I am assuming. C2H2 + N2O ---> CO2 + N2 + H2O. Now this may seem like a retarded question, but how can there be two oxygen molecules in the...

can we use some conversion types of chemistry in electrical. Lke in chemistry we used to calculate that if mass of 50g require 500ml of water to dissolve then mass of 10g requires = (500*10)/50 . similarly can we use the same tecnique to find some electrical quantities for example dielectric of...

Hello! Is it possible to study the organic chemistry without the firm knowledge of general chemistry? I took the general chemistry on last year and will take the organic chemistry on this Fall but I forgot the majority of topics from general chemistry...I heard that organic chemistry is quite...

Homework Statement The redox reaction of peroxydisulfate with iodide has been used for many years as part of the iodine clock reaction which introduces students to kinetics. If E°cell = 1.587 V and E° of the cathode half-cell is 0.536 V, what is E° of the anode half-cell? S2O82–(aq) + 2H+ +...

I have been doing research in chemistry for quite a while now. I love chemistry! But for about a year now, all of the questions that I've had are of a more purely physical nature. My mentor has some good answers for me, but a lot of the time he doesn't seem to care or know about the answer. He...

Hello! For those who took (or have been taking) the organic chemistry, which methodology do you prefer to tackle the mechanism and prediction questions? I have been reading Loudon & Wade (functional group-based) and Clayden (mechanism-based), but I feel like the mechanism-based approach is...

I'm having trouble deciding between the two as I don't want to go into any specific field, my goal is just to be in a position to have a proper career. I don't know which subject has more prospects in the industry but I'll probably want to progress to a masters eventually and obviously will have...

I will be applying for schools soon in physics, although my bachelors is in chemistry. Although I have decided that I would rather pursue physics than chemistry in graduate school, at the moment, I do not have my heart set on any specific sub-discipline of physics. So, assuming I have absolutely...

Hello! I am a rising sophomore with double majors in a chemistry and microbiology. The reason I wrote this post is to seek your advice on my plan to review the chemistry for myself and for the research lab; I am currently working for the synthetic chemistry lab that focuses on the...

Well i want to see what do you prefer and why?

Hello! I have some questions about the textbooks in the organic chemistry. I have been using the organic textbooks by L.G. Wade, Clayden, and Loudon. I love those books, but I have been hearing that the textbooks wrote by Klein, Carey, Morrison Boyd, and Hornback are really good. Do I...

I am about to take a teacher certification test for HS Chemistry. I would love to get suggestions from you on the friendliest textbook available out there for self studying, since I will study entirely on my own. The scope would be about two-semester introductory college level, I would also...

Hello! I am a rising sophomore with double major in a microbiology and a chemistry. I wrote this thread because I need a guidance in the course selection for the upcoming Fall Semester. Is taking both organic chemistry and biochemistry a good idea? I know that the biochemistry is based on...

Hello everyone, I am new here and have been digging through the forums to see if my problem has been discussed before, but couldn't really find the answers I was looking for. I am a community college student transferring to university this fall, majoring in physics. However I have had this...

In the chemical engineering curriculum I saw "general chemistry for engineers." How different is it from regular general chemistry which everyone else takes? We are currently using Burdge chemistry. Besides regular problems and additional exercises it does have biological and engineering...

Hi, What software could you recommend for making complex physics and chemistry charts (for better overview) like the following 3 examples? Exapmple of SI. Units in physics http://physics.nist.gov/cuu/Units/i/SubwayDiagram.gif Chemistry chart...

Hi, I've red the first 4 chapters in Clayden Organic chemistry, and I got to admit I find the first chapters on NMR and Orbital theory lacking in explanation and figures. I don't feel like i have a clear understanding of the concept after reading these chapters because they seem to assume...