Concentration Definition and 583 Threads

In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. A concentration can be any kind of chemical mixture, but most frequently solutes and solvents in solutions. The molar (amount) concentration has variants such as normal concentration and osmotic concentration.

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  1. Muhammad Usman

    I Concentration of Impurities in Extrinsic Semiconductor ?

    Hi, I was studying a book on analysis and design of analog integrated circuits. In the book it is mentioned as "For practical concentration of impurities, the density of majority carriers is approximately equal to the density of impurity atoms in the crystal" I researched about it and I found...
  2. K

    Calculate the concentration ratio

    Any hint? I was immediately thinking standard electrode potentials as we have two half reactions, but not sure exactly how to go on..
  3. R

    Reduction in gas concentration of water with solutes

    When salt (polar) is added to water (polar) it makes the water more polar and causes the oxygen (non-polar) to be "driven" from solution. So I'm assuming this is an electrostatic repulsion(?). Aside from salt what other solutes would cause this to happen? Would a solute have to have very polar...
  4. S

    Find the acceptable concentration of CO

    Homework Statement Based on the “National Ambient Air Quality Objectives”, the acceptable hourly average concentration of carbon monoxide (CO) is 35 mg/m^3. Find the acceptable concentration of CO in ppm if the temperature is -30 °C and pressure is 0.92 atm. Express the concentration as a...
  5. R

    Expected concentration of fluoride released from PFAA

    Homework Statement You have 200 mL of perfluorooctanesulfonic acid with a concentration of 10 mg/L. If the PFOS is completely mineralised in solution what is the expected concentration of fluoride in solution? The experimentally determined fluoride concentration is 5.6 mg/L Homework Equations...
  6. J

    The concentration of B at equilibrium

    Homework Statement For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00L container. A(g) + 2B(g) --> C(g) At equilibrium, the concentration of A is 0.246 mol/L. What is the concentration of B at equilibrium? Homework Equations for aA+bB-->cC, K = [C]^c/([A]^a[...
  7. S

    PH of citric acid solution at different concentrations

    What is the PH of 20%, 40% and 60% concentration of the citric acid solution?
  8. harambe

    Where Did I Go Wrong in Calculating Hydroxide Ion Concentration?

    Homework Statement The hydroxide ion concentration in an aques H2CO3 solution is 4X10^{-4}M at 25°C OH- ion concentration in the solution is Homework Equations Ph=log(H+ or OH-) [/B]The Attempt at a Solution I calculated the PH of H+ in the solution which came to be 4.3979.Considering...
  9. P

    Surface tension in terms of temperature and concentration of an added substance

    Hi! Here's a tricky thermodynamics problem, I hope you can help with it. 1. Homework Statement The boundary between two different materials can be divided into two different kind of phases: bulk phases and surface phases. For example, let's consider a boundary between water and air. We can...
  10. N

    MHB Help with solution concentration

    Hi I'm looking for some help that I think is easy but just can't get my head round. So I need to make a solution with a concentration of 10% bleach to remove DNA contamination from equipment. So if I had 100ml of water I'd need 10ml of bleach to make a 10% solution. But it is the active chlorine...
  11. somasimple

    Can Composition Reveal Solute Concentration?

    Hi All, Is it possible to know the concentration of a solute when you have only its composition? I.e : the solute contains 1 molecule of water for each k+
  12. M

    Mechanical engineering - Stress concentration

    1. In my materials science's exam, I had the following question: What would be the maximum force F to cause failure in a block that has been drilled at two place? See following drawing: (Lame paint skills, I know..) 2. Homework Equations 1) D/W 2) σ = F/S The Attempt at a Solution 1)First...
  13. B

    Calc Electron & Hole Concen in Silicon at 300K

    Homework Statement For silicon at T=300K with donor density ND=2×109cm−3, acceptor density NA=0 and ni=8.2×109cm−3, calculate the equilibrium electron and hole concentration Homework Equations n_0=\frac{N_D-N_A}{2}+\sqrt{\frac{N_D-N_A}{2}^2+n_i^2} p_o=\frac{n_i^2}{n_0} The Attempt at a...
  14. somasimple

    Exploring the Limits of the Nernst Equation in Concentration Cell Experiments

    Hi All, (Just for information and understanding), If we have a concentration cell experiment like the image uploaded, in a concentration cell, the solutes are supposed to be of the same kind, iI.e. CuCl2 (?). I suppose it is possible to add to the left vat a m quantity or volume of CuSO4 to...
  15. G

    Chemistry How to Convert a Number Concentration into Volume Mixing Ratio?

    Homework Statement Convert a number concentration of 15 X 10^12 molecule/cm3 into volume mixing ratio at: a) 1 atm pressure, and 20 C temperature. b) 500 mbar pressure, and 253 K temperature. Using the Ideal Gas Law, calculate: a) Loshmidt’s number (# of molecules/cm3 of air, at standard...
  16. Krushnaraj Pandya

    How Does NaOH Affect the Degree of Dissociation of Triethylamine?

    Homework Statement The ionization constant of ## {(C_2 H_5)}_3 {N}## is 6.4 x 10^(-5). Calculate degree of dissociation in its 0.1 M solution when it is mixed with 0.01 M NaOH solution. 2. The attempt at a solution the compound gives ##{(C_2 H_5)}_3 {NH+}## and ##OH-##. C is initial...
  17. J

    Difference between diluting and adding

    Homework Statement Place 20.0 g NaOH(s) in a flask and dilute to 1.00 L with water. Place 20.0 g NaOH(s) in a flask and add 1.00 L of water. How exactly do these two statements differ? Wouldn't adding 1.00L of water to 20.0g of NaOH dilute it anyways? Homework Equations none? The Attempt...
  18. R

    Stress concentration factor and notch sensitivity in a shaft

    Homework Statement [/B] I can't seem to get the image links to work sorry! Also, I think the question is supposed to say 2.5mm radius notch, not 10mm https://imgur.com/Klxw4gG https://imgur.com/C9d81Rl https://imgur.com/7H421ou Homework Equations [/B] q = Ka - 1 / Kt - 1 M = Fd (σa / σ'e)...
  19. J

    Calculate pH of NaF Solutions | 0.30 M

    Homework Statement Calculate the pH of the following solutions: (caution: these are hydrolysis reactions) a. an 0.30 M solution of NaF Homework Equations I think by hydrolysis reactions they mean that each of the given compounds is combined with $H_2O$. Then for a) NaF + HF <-->...
  20. J

    Calculate the pH of a 0.20 M solution of iodic acid (HIO3).

    Homework Statement Calculate the pH of a 0.20 M solution of iodic acid ##(HIO_3)##. ##K_a## for iodic acid is 0.17 Homework Equations ##K_a = \frac{[H^+][IO_3^-]}{[HIO_3]}## The Attempt at a Solution ##[HIO_3] = 0.20## M. The concentration of ##[H^+]## and ##[IO_3^-]## should be the same...
  21. B

    Linear Algebra System of Equations/Rates Application Help

    Homework Statement Suppose that we have a system consisting of two interconnected tanks, each containing a brine solution. Tank A contains x(t) pounds of salt in 200 gallons of brine, and tank B contains y(t) pounds of salt in 300 gallons of brine. The mixture in each tank is kept uniform by...
  22. R

    Programs Too Many classes? (math major with a concentration in Pre-Medicine)

    I am a math major with a concentration in Pre-Medicine and I am setting up my program for next year. I was wondering if taking Bio w/ a lab, Chem w/ a lab, Calc II and Linear algebra is just an unrealistic idea.
  23. Hallucinogen

    Concentration from density and purity

    Homework Statement This isn't homework, rather it's regular work. I have a >97% solution of 1-thioglycerol, the density of which is 1.25 g/mL. I am trying to get a 1.5 x 10-4 M solution at the end, and I suspect the instructions I have been given are incorrect. Molar mass = 108.16 Homework...
  24. K

    A Fatigue stress concentration factor (Kf)

    Hi, I had been reading about the fatigue stress concentration factor (Kf) which is reduced compared to the geometric stress concentration factor (Kt). The reduction in turn dpends upon the material's sensitivity to notches...
  25. M

    Studying Does white noise impair studying, reading or recall/memor?

    Hi, I recently have been trying to look into whether or not white noise works as a means to block out external sounds so i can concentrate. However, I want to know whether it actually impairs studying and reading. I do not care if it has no benefit, as long as it has no negative effects. I am...
  26. T

    Programs PHD in Computer Science with a concentration in Chaos Theory

    Hi everyone, I am working on a second bachelor's degree in Computer Science, and am hoping to enter a Phd program in fall of 2019. Recently, I have taken an interest in Chaos Theory and was wondering if it is possible to do research in the field in the Computer Science department, or if it is...
  27. D

    PFR reactor, concentration profile

    When I set the differential equation (mass transfer) to find the the concentration profile of the i-spice I also need boundary condition to solve it. Inside the pipe (along its axis of symmetry) the concentration has a maximum (first derivate has to be 0), while on the internal surface... should...
  28. maistral

    Tracer concentration + effective residence time for a basin

    I'm very sorry for the lengthy post. I'm actually not sure as to how to deal with this as this is the first time I've been assigned to these kinds of problems; I need to be sure. Thanks in advance. So I have this large basin-like structure whose water naturally has K+ ions dissolved in it...
  29. Revengeance

    Concentration of Ions at Equilibrium

    Homework Statement Find the concentrations of all ions in the solution at equilibrium after 0.213 L of 0.433 M aqueous Cu(NO3)2 solution is mixed with 0.213 L of 0.120 M KOH solution. Ksp for Cu(OH)2 is 1.1E-15. Homework Equations n=m/M [Cu][OH]^2 = Ksp .. ?The Attempt at a Solution ok so for...
  30. L

    Quick Question about a Concentration Problem

    Homework Statement Homework Equations M = n/1 L The Attempt at a Solution I was wondering if the answer is 6E. I'm not too sure about what the question is asking but i do know that the more moles there are, the more concetration of ions there will be. So, E seems like the answer since it...
  31. Kara386

    Intrinsic carrier concentration where did I go wrong?

    Homework Statement I've looked up the intrinsic carrier concentration of silicon, and what I've got isn't close. The question says given there are ##2\times 10^{22}## electrons per cubic cm in silicon, and the bandgap is ##1.1##eV, what is the free electron concentration at room temperature...
  32. L

    Simple Concentration Stoic Problem?

    Homework Statement What mass of aluminum nitrate should be dissolved in 225 ml of water to make a solute with a total nitrate concentration of 0.866 M ? Homework Equations M = n/L The Attempt at a Solution So, i keep getting the wrong answer. THe answer is suppose to be 13.8 g but i get a...
  33. P

    How to calculate weight needed for a concentration

    I haven't had a chemistry class in many years. Recently I saw an interesting article that used a solution of resveratrol (228.25 grams per mole) in dimethylsulfoxide (78.13 grams per mole). The concentration was listed as 5 uMol. If I had 10 grams of DMSO how much resveratrol would I add to...
  34. S

    Why Are My Liquid Analyzing Device Results Inconsistent at Low Concentrations?

    I made liquid analyzing device based on beer lambert law. I am getting very accurate results when using rich colored liquids but when concentration of colored liquid is dropping beyond certain level I am getting non consistent results. Example: Mixing 2 liquids with concentration 10:1 or 30:1 I...
  35. vanessa99

    Is a 10-Hour Study Schedule with Regular Breaks Effective for Concentration?

    Hello everyone! So I made a study program and it's 10 hours studying per day. I will have it everyday till May. After 30 min of studying I take a 5 min break and after 2 hours, 15 min break. Is that sound bad? Plus, till now due to different factors I have studied around 4 hours per day. How...
  36. HelloCthulhu

    What is the molality of 1M NH4OH in 70.092ml of water?

    Homework Statement What is the molality of 1M NH4OH dissolved in 70.092ml of water? What is the total mass of the solution? What is the total volume? What is the concentration percent? What is the molar concentration? 1M NH4OH = 35.046g density of water = 1g/ml density of NH4OH = 0.88 g/ml...
  37. T

    Trouble finding where I went wrong calculating concentration

    In our laboratory class we were required to calculate the stock (mM) and final (µM) concentrations for Glycerol. The tutor said my final calculations were incorrect and that I had made an error. He didn't have enough time show me where I went wrong. I have compared my results with another...
  38. N

    Concentration gradient force Vs. electrical gradient force

    Hi Everyone, I was just learning about action potential generation via electrochemical gradients. I was just wondering, does anyone know whether a +1 unit of concentration gradient is stronger/weaker than a +1 unit of electrical gradient? For example: If side-A of a split chamber had a net...
  39. R

    Refractive index as a function of the concentration of a sugar solution

    We recently performed an experiment with the idea to find refractive index of medium (water) as a function of wavelength of light. We then added some sugar to see how the refractive index changes with concentration of sugar solution. We got the following graphs. Are the relationships actually...
  40. S

    Exploring the Relationship between Concentration & Refractive Index

    < Mentor Note -- two threads merged and new user reminded not to multiple-post threads at the PF > i'm experimenting about refractive index and i can't figure out the relationship between concentration of the solution and Refractive index. What i found about this is that RI is connected to...
  41. Frankenstein19

    Mass of ammonia through nitrate concentration problem

    Homework Statement The nitrate concentration in an aquifer is 20 ppm, and its volume is ten million liters. What mass of ammonia upon oxidation would have produced this mass of nitrate? [Hint: The moles of nitrogen in reactant and product are identical.] Homework Equations Possibly 1mg/L &...
  42. D

    I Formula for concentration of force (battle axe vs. a mace)

    I really hope someone can help. I have spent the last week several hours a day trying to get this answer via Google. I am doing research on the practical difference between a mace and axe in combat. Strangely enough there's almost nothing concerning the techniques of using a mace in period...
  43. J

    Concentration of a salt produced by neutralization reaction

    Homework Statement 10.00 cm3 of 1.00 mol dm–3 sulfuric acid is fully neutralized by 20.00 cm3 of 1.00 mol dm–3 of sodium hydroxide. What is the concentration, in mol dm–3, of sodium sulfate solution produced by the reaction? A 0.33 B 0.50 C 0.67 D 1.00 Correct answer = A Homework Equations...
  44. E

    I Concentration of R-G centers in a PN junction

    Hey guys, Currently taking a semiconductor device fundamentals course and we are learning about R-G currents in the depletion region of a PN junction. Usually we just consider R-G centers as impurities to be avoided in the operation of a standard rectifying diode. However, I was curious as to...
  45. G

    Find Axial Force P: Stress Concentration Homework

    Homework Statement The stress distribution along the section of a bar is shown below. From this distribution, find the approximate axial force P in kip. Homework Equations δavg=P/A A= (.6+.6)(.5) δavg=30ksi[/B]The Attempt at a Solution P=(30ksi)(.6in2)=18kip It says this answer is wrong...
  46. I

    Titration Exam Question 1: Calculating Concentration of Undiluted Nitric Acid

    1. The problem statement, "all variables and given/known data A solution of nitric acid, HNO3, of concentration 100 g dm-3, can be used to artificially age wood. A sample of nitric acid was tested by pipetting 10.00 cm3 of the acid into a 250 cm3 volumetric flask and filled up with deionised...
  47. Jane Bondarenko

    Salt concentration and its electrical resistance

    What would be the theoretical relationship between/ a formula for the salt concentration in distilled water and its electrical resistance?
  48. C

    Programs Optics Program or Physics Program (w/ optics concentration)

    My main goal is optics. I love it. I did an internship having to study and learn about optics and I've had my sights set on it sense then. It's also easier for me to learn. I've applied to graduate schools, but I need to know: Are there any advantages or disadvantages of going to an optics...
  49. T

    Analytical Chemistry Concentration Calc Question

    A lab mate and I are discussing how to properly interpret LCMS results and coming to different conclusions. We are taking a solid food sample and extracting it with 50:50 acetonitrile/water to determine the concentration of melamine in the food sample. Standard solutions were made that range...
  50. D

    Phase Diagrams at Very Low Concentration of one Component

    What happens to one of the components when it is at VERY low concentration in a two component alloy? My problem: Uranium decays to thorium. The thorium isotopes it decays to typically have pretty short half lives. During casting, it is well known that thorium fractionates to the slag, crucible...
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