What is Concentration: Definition and 583 Discussions

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. P

    Fermi energy level in terms of Na and Nd the concentration of dopant?

    fermi level?? is there any relation ( equation) that give the fermi energy level in terms of Na and Nd the concentration of dopant??
  2. K

    Concentration of synthesized nanoparticles

    Hi! I am dealing with the synthesis of inorganic metallic nanoparticles and at the moment looking for the methods how to define the concentration of final nanoparticles in the colloidal solution.
  3. N

    Question on concentration of pigment in textile fibers

    Hi! I am looking for some help with understanding what are the "usual" values for concentration of pigments in textile fibers. Would appreciate any help, links, comments.. I did some search on the Internet. The resource that I was able to find is this...
  4. B

    Titration method to determine HCl concentration in a mixture

    I have a solution which contains unknown amount of dissolved ferric chloride (FeCl3) and hydrochloric acid. Can I use the titration method with NaOH to determine the concentration of HCl? I was concerned since dissolved FeCl3 is also acidic, and the fact that NaOH will try to neutralize it...
  5. J

    Drop in Concentration as reaction progresses

    Homework Statement I am currently doing an investigation into the reaction between different acids and magnesium metal. I want to try and show that by using a large volume of acid the concentration drop as the reaction progresses is significantly reduced. Is there any way of doing this...
  6. T

    Solved: Calculate Ion Concentration (27.6 g)

    [SOLVED] Ion concentration Homework Statement http://img225.imageshack.us/img225/9918/chemch0.jpg Homework Equations C = n/v The Attempt at a Solution My work is shown up above. Sorry if my work looks a little messy. My answer is 27.6 grams.
  7. S

    Concentration of ammonia in a solution

    Hello all, I had chemistry a long time ago, but now I am very rusty at it :frown: so I am hoping you can get me started with this problem I have; A particular solution of ammonia (Kb = 1.8 x 10-5) has a pH of 8.3. What is the concentration of ammonia in this solution? Is it the...
  8. S

    Solution concentration and ppm

    Hi all, I have 2 short questions, that have caused me trouble in my study. Firstly, What is generally considered to be a highly concentrated solution? eg. 250mL acid in 10L water. This is 250E-3/10 = 0.25/10 = 0.025 M. Would that be considered a concentrated solution? as it seems very low...
  9. M

    Solve 0.1% w/w Concentration Problem: Beer's Law & C15H6N4

    Problem: Assume the human eye can detect light with transmittance of 0.35. The colored form of the indicator has ε = 8.79 x 10^5. and λmax = 580 nm. How much indicator in ml should be used if the indicator has concentration 0.1% w/w in water. Equation Used: Beer's Law = A = εbc where ε...
  10. D

    Titration - solving for a one concentration knowing the other reactant

    Homework Statement A 10.02 mL solution of chemical A4+ is determined by precipitation titration with 40.07 mL of 0.03015 M titrant B3-. The reaction stoichiometry is given by 3A4+ + 4B3- => A3B4 (s) For a log Ksp of -36.6, what is pB3- at the equivalence point? You must express your...
  11. J

    Chemistry Molecules in 1 mL of 1.0x10^-22 M AsCl3: Verification and Calculation

    Hey, just wondering if i can get some verification with my answers. I need to find the number of molecules from a concentration that is 1.0x10^-22 M of AsCl3 in one mL. I divided my concentration by 1000mL to get it down to a concentration per mL and multiplied by avogrado's number. My...
  12. B

    How to Calc molar concentration from Ksp

    What is the Molar Concentration of Sr(CO3)3 if Ksp=9.3 X10^-10 I believe you have to balance the equation and i got Sr(CO3)3= Sr + 3 CO3
  13. F

    Basic Semiconductors (intrinsic concentration)

    Ok, so in an intrinsic semiconductor we know that the intrinsic concentration ( n_i ) is roughly 10^10 cm^{-3} at room temperature, and that n=p=n_i under equilibrium conditions. Now why is it that at zero temperature, (i.e. 0K ) does n_i have any value? I know that that n_i does...
  14. D

    [Chem] Determining Masses from Concentration

    Homework Statement In lab, a student decides to analyze a 0.6118 g sample containing only magnesium chloride and sodium chloride. He does this by adding 145 milliliters of 0.1006 M silver nitrate. A precipitate, silver chloride, is formed, which has a mass of 1.7272 grams. Using this data...
  15. M

    How to calculate the carrier concentration

    Can any please help me in solving the following two questions Q1 A Si sample is doped with 10^16 per cm cube boron atoms and a certain number of shallow donors. The fermi level (Ef) is 0.36 eV above Ei (intrinsic energy level) at 300K. What is the donor concentration Nd? For Si at 300K...
  16. F

    Absorbance and Concentration Question

    Homework Statement The protein oxyhemoglobin has the following molar absorbance coefficients: \epsilon276 nm = 3.44 x10^{4}M^{-1}cm^{-1} \epsilon415 nm = 1.25 x 10^{5}M^{-1}cm^{-1} If a solutioin of oxyhemoglobin has an absorbance at 415nm of 0.234, a) What is the concentration at 415nm...
  17. A

    Finding Free Electrons and Hole Concentration

    Homework Statement Silicon is doped with an Aluminum Concentration of 2 X 10^16 cm^-3 What are the free electron and hole concentrations at room temperature? What are the electron and hole mobilities at 300K? What is the majority carrier? What is the minority carrier? Homework...
  18. B

    Finding the iodide ion concentration

    Homework Statement What is the iodide ion concentration in a solution if the addition of an excess of 0.100 M Pb(NO3)2 to 37.2 mL of the solution produces 539.7 mg of PbI2? Homework Equations possibly c(1)*V(1)=c(2)*V(2) is pertinent to the problem The Attempt at a Solution I...
  19. B

    What is the concentration of Br1- ions in a solution of 0.0330% AlBr3?

    Homework Statement A solution is found to be 0.0330% by weight AlBr3. What is the concentration of the Br1- ion expressed in ppm? Homework Equations The Attempt at a Solution Assume .0330 % => .0330 g AlBr3 .0330 g AlBr3*(1 mol AlBr3/266.697 g AlBr3)*(3 mol Br^-1 /1 mol...
  20. J

    Equilibrium Concentration of NO in N2/O2 Mixture at 2000 K

    Considering the following N2+ O2= 2NO at 2000 K is 4.0 × 10-4. Consider an initial mixure of 10 moles of N2 and and one mole of O2. How do I find the concentration of NO in the equilibrium mixture in ppm? thank you:confused:
  21. N

    Calculating Concentration of CO in a Mixture

    CO oxidation ?? There are two cylinders. First is a CO cylinder having pure 99.97 CO gas and second having zero air. CO is given at 0.1LPM rate and air at 0.9LPM. what is the concentration of CO and what percentage in this mixture?? How to figure it out?
  22. P

    Concentration of Caco3 in water flow on leaned flat surfaces with rain channels

    Homework Statement On flat, leaned, surfaces, there are channels (rillenkarren), which are made by dissolution by rainwater (http://mafija.fmf.uni-lj.si/seminar/files/2005_2006/rillenkarren.pdf - not very important). They are 2-3 cm wide and around 0.5 m long. The formation is not yet known...
  23. M

    Effective density & Intrinsic carrier concentration

    Homework Statement Given "n=Nc*e-(Ec-Ef)/KT", prove "n=ni*e(Ef-Efi)/KT" Homework Equations Quasi-Fermi Energies..? Ef is Fermi level (extrinsic) and Efi is Fermi level (intrinsic). Ec is Fermi level (conduction). The Attempt at a Solution Very honestly, I cannot figure out how to...
  24. J

    Find the Concentration of Cu2+ in Unknown Solution

    Homework Statement What is the concentration of the unknown Cu2+ solution? The reaction is Zn(s) + Cu2+(aq) -> Zn2+(aq) + Cu(s). The concentration of Zn2+ is 0.05 M Homework Equations The Attempt at a Solution I'm coming up with about 2 different answers, and I'm not sure which is correct...
  25. Q_Goest

    Stress Concentration, Stepped Shaft

    Most texts have stress concentration factors for a stepped shaft in tension that has a radius where the smaller shaft meets the larger one such as this reference: http://www.pirate4x4.com/tech/billavista/PR-BV60/Materials/7.jpg I'm looking for a reference (perhaps "Peterson's Stress...
  26. A

    Stress Concentration around a circular hole on a flat rectangular plate

    Can anyone help with how to find the analytical solution to problem involving finding the stress concentration around a circular hole in a flat plate. The plate is has tensile load on both sides.
  27. C

    Higher Chemical Concentration = Higher Temperature of Precipitation. Why?

    If two chemicals are mixed together If I had varying concentrations of the reactant solutions, why is it that the higher concentration mixtures will precipitate at a higher temperature? and lower concentration chemicals will precipitate at a lower temperature?
  28. T

    Effects of HCl Concentration on Magnesium (HCl + Mg)

    Hi.. Im trying to figure out what the affect of HCl on a magnesium strip at different concentration levels has? I can't figure out a 'scientific' response and therefore can't formulate a hypothesis :/ Any help will be appreciated.
  29. S

    Higher Chemical Concentration = Higher Temperature of Precipitation. Why?

    If two chemicals are mixed together, say: Na_2SO_4 + CaCl_2 --> 2NaCl + CaSO_4 If I had varying concentrations of the reactant solutions, why is it that the higher concentration mixtures will precipitate at a higher temperature? and lower concentration chemicals will precipitate at a lower...
  30. J

    [Chemistry] How do you find the new concentration?

    Homework Statement For solution A the concentration is 7.00x10^-4 mol/L. You transfer 10ml of the solution A out into a 10 dram vial and add 10mL of 0.1M HCL acid solution, and the new mixture is called solution B. What is the concentration of solution B? Homework Equations The Attempt...
  31. B

    Confused about Free Energy relation to Pressure & Concentration

    I'm not sure whether this belongs in the chemistry section, but since it concerns free energy, I decided to post it here. My chemistry text, Zumdhal, says (without proof, I am self-studying a first year college-level chem course) that \Delta G = \Delta G^{\circ} + RTln(Q), where Q is the...
  32. A

    What Is the Equilibrium Concentration of CO in the Reaction at 400K?

    Homework Statement CO(g) + NH_3(g) ...> HCONH_2(g) euilibrium constant is: K = 0.207 at 400 K If a reaction is filled with intial concentrations 2.20 M of CO and 2.60 M of NH_3 and the reactanats are allowed to raect at 400K/ what will be the concentrations of CO at equilibrium ...
  33. R

    Finding the concentration of a gas (thermodynamics)

    Hi. Homework Statement The root mean square velocity of oxygen molecules is 480m/s while the pressure is 20kPa. What is the concentration (particles/volume) of oxygen? Homework Equations PV=nRT E_{kin}=\frac{m \overline{v}^2}{2}=\frac{3}{2}kT The Attempt at a Solution m...
  34. P

    Ozone Concentration: 25 Dobson Units

    Homework Statement If the ozone concentration in a particular sample of air were 25 dobson units, what sould this concentration be in: a)ppm b) %(v/v)Homework Equations 1 dob = 2.69*10^20 ozone molecules / m^2 http://en.wikipedia.org/wiki/OzoneThe Attempt at a Solution The question is asking...
  35. Y

    Calculating Hydrogen Ion Concentration & PH: A Guide by Yonderboy98

    I know what the formal definition of ph is, and I am comfortable with logarithms, anti-logs, and the laws of exponents. Still, I get confused doing actual calculations and would greatly appreciate your input on the following: Suppose something has a ph of 3.5-How do you calculate the hydrogen...
  36. Mk

    Why is the CO2 concentration so erratic in the north?

    0? latitude and north, the CO2 concentration over time goes from rather soft to erratic. What is responsible for this? Also, what is the mechanism in which CO2 concentration drops and rises every year?
  37. T

    Stress concentration sensitivity definition

    what is the defination for the following:stress concentration sensitivity, fracture load cycle, notch size factor?? pls help thanx
  38. T

    Stress Concentration: Notch Radians & Formula

    does anybody knows what is and how to find notch radians??any formula??
  39. T

    Critical Section Location in Stepped Shaft Under Torque Load

    What are the cases for section 1 and 3?? this is a stress concentration factor of notched or fillet bars problem. From the picture,how can we choose whether it is t=tension,z=compression or b=bending?? http://files.filefront.com//;5410211;;/ and...
  40. K

    PH & Concentration Help - Problem Solving

    Hi, I need some help with a few problems. Thanks! (1) You have a pH Electrode that reports a voltage in mV, which is proportional to the hydrogen ion concentration in solution. You also have pH buffers at known pH of say 4, 7 and 10. What do you do to translate the mV reading into pH...
  41. M

    Schools What colleges have a nuclear concentration?

    I am looking for a college with a nuclear concentration in physics. What are the top colleges to be looking at? Right now on my list is Reed College, and RPI. Thanks!
  42. R

    How to Calculate Solution Mixture for Iodine Concentration - 20% and 70%

    Sarah wants to mix 400 liters of a solution that is 57.5 iodine. She has two solutions available. One is 20% iodine and the other is 70% iodine. How many liters of both should Sarah use? Answer in the form: 20% = ?, 70% = ?
  43. L

    How can concentration be calculated in a chemical experiment?

    I was wondering if anyone knows how to measure concentration. I'm going to have a lab prac. where we design an experiment to investigate the effect of concentration in the rate of reaction of calcium carbonate and hydrochloric acid. I already know that increasing the concentration will...
  44. M

    Does water/ or solid have concentration?

    does water/ or solid have concentration? does water/ or solid have concentration? Why do we just ignore the concentration of solid or solution solvent and replace it as one M? I always thought the reason is because the concentration of solid or water solvent does not change much so in...
  45. A

    Exploring Water Concentration: An Essential Factor in Chemical Reactions

    my answer would be yes because, a concentration is the measure of how much of a given substance there is mixed with another substance, so aslong as the water is mixed with something elce you can measure the concentation of water right?
  46. C

    How Do You Calculate the Increase in H2 to Double NH3 at Equilibrium?

    A 1.00L vessel contains at equilibrium 0.300 mol of N_2, 0.400 mol H_2 and 0.100 mol NH_3. If the temp is maintained constant, how many moles of H_2 must be introduced into the vessel in order to double the equilibrium concentration of NH_3 I said that if I let the change in conc. of H_2 be...
  47. P

    How to Improve My Study Habits and Concentration

    studying was not a problem for me and i don't hate studying,but recently there has been a problem which has cropped up, here it is What i find is the knowledge/information is quite distributed, for eg there is not a single good textbook which can satisfy me, and so therefore i tempt to plan to...
  48. M

    Drug Concentration: Estimating Drug Levels in the Body

    If you ingest a drug, is there a mathematical formula that models how much of the drug is left in the system?
  49. T

    Concentration problems (I guess )

    This week Electrodynamics test, and last week QM test have really made my cup full. Instead of 100% on QM test I scored 80% because I missed one of the terms in a verry verry long equation (some variational problem with verry ugly hamiltonian in cylindrical coordinates) when I was rewriting it...
  50. K

    Concentration of Ions in Ba(OH)2 + NiSO4 Reaction

    While waiting for my other post to be moved, I'm putting this question up again. 25.00 mL of .1857 M Ba(OH)2 reacts with 30.00mL of .2228M NiSO4. Find the concentration of all ions after the reaction assuming that final volume is the sum of the initial volumes. Ba(OH)2 + NiSO4 -> BaSO4 +...
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