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. M

    Chemistry - Concentration from known pH and Ka.

    Homework Statement A particular sample of vinegar has a pH of 2.90. If acetic acid is the only acid that vinegar contains (Ka = 1.8 x 10-5), calculate the concentration of acetic acid in the vinegar. Homework Equations Ka = [Products]/[Reactants] pH = -log[H+] The Attempt at a...
  2. A

    Electron-Hole Concentration vs. Carrier Density

    I'm a bit unclear on terminology with semiconductors: is there a difference between the "intrinsic carrier density" and the "electron concentration" or "hole concentration"?
  3. M

    Finding the Concentration of H3CO2 in a CO2+H2O reaction.

    1. Find the equlibrium constant if there is 0.030moles/L of Carbon Dioxide going in the forward direction and water is in excess to form Carbonic Acid (H2CO3) Homework Equations [products]/[reactants] = K The Attempt at a Solution I'm trying to figure out how Carbon Dioxide in...
  4. G

    Determining Initial and Equilibrium Concentration (Help )

    Determining Initial and Equilibrium Concentration (Help!) Homework Statement You are given the equation Fe3+ + SCN- -> FeSCN- You are performing an experiment in which you are mixing Fe(NO3)3 and NaSCN. A table is given and I will only list the first sets of data because if i can figure out...
  5. M

    I have question,The electron and hole concentration in a intrinsic

    I have question, The electron and hole concentration in a intrinsic semiconductor are n1 and p1 respectively.When doped with a p-type material these change to n and p repectively,then a)n+p = n1+p1 b)n+n1= p+p1 c)np1 = n1p d)np = n1p1 could anyone explain what would be the solution. I...
  6. N

    Can Exercise Improve Concentration and Focus?

    What are the current accepted paradigms on concentration and Focus? I want to know more information about it, links are also greatly appreciated. Sometimes I can study for a very long-period of time with complete concentration. And other times I just can't seem to focus as much as I would...
  7. K

    Solving Concentration Problems: Sodium Cations

    Homework Statement 15 cm3 of 0.200 mol dm-3 sodium hydroxide solution was made up to 100 cm3 with 0.120 mol dm-3 sodium sulfate solution. Determine the molar concentration of sodium cations in the resultant mixture. 2. The attempt at a solution Moles of sodium ions in sodium hydroxide =...
  8. J

    Simple questions on solutions concentration and pH

    Hi there, I was wondering if anyone could help me with 3 questions: 1) Without pH papers, how do you calculate the pH of a 5% H2SO4 (sulfuric acid) solution? I know vinegar is a weak acid, but would a 5% acetic acid have the same pH of a %5 H2So4 solution? 2) If a non-polar solvent...
  9. P

    C2H3O2- concentration given pH of 30mL NaC2H3O2 solution

    I'm working on a lab for my chem class and we have to calculate all of the different ion concentrations within some titrations that we did. Here I have to calculate the concentration before anything is added. Na+ + C2H3O2- + H2O → HC2H3O2 + OH- + Na+ the pH is 8.4458 for a 30.0 mL NaC2H3O2...
  10. C

    There is a high concentration of introductory material on wave-particle duality

    (A disclaimer: I'm not an expert, having genuine confusion) There is a high concentration of introductory material on wave-particle duality that claims that the uncertainty principle manifests itself identically to the behavior of waves in the macro world. This however appears to be in direct...
  11. L

    Calculating concentration of product & mass of a precipitate

    The question is: 100 mL of 0.2 mol/L sodium carbonate solution and 200 mL of 0.1 mol/L calcium nitrate solution are mixed together. Calculate the mass of calcium carbonate that would precipitate and the concentration of the sodium nitrate solution that will be produced. I believe the...
  12. P

    Electrochemistry, emf vs HCL concentration

    Homework Statement I just conducted a lab for pchem where we took electric potential measurements with a volt meter in a solution for the reaction AgCl(s) +1/2 H2 (g) <--> HCl(aq) + Ag(s) We took the measurements using different concentrations of HCl. We were told that the...
  13. R

    Concentration of Radon in atoms per cubic meter

    Homework Statement i) The average concentration of 222Rn in air inside a building is 20Bqm-3; what is the average concentration of Rn in atoms per cubic meter? ii) In a sealed room of volume 50m3 what activity of 238U in a piece of porous rock would eventually give rise to this 222Rn...
  14. R

    Weight Percent Concentration

    Homework Statement What is the weight percent concentration of a saline solution prepared by dissolving 2.440 mole of KCl in 10 L of water? Homework Equations The Attempt at a Solution
  15. J

    Chemistry Question Solution Stochiometry And Determining The Concentration?

    Homework Statement What is the concentration of all ions after 600.0mL of 2.00 mol/L Barium nitrate is added to 100.0 mL of 2.50 mol/L sodium phosphate. The Attempt at a Solution I first wrote down the equation : 3Ba(No3)2 + 2Na3PO4 = Ba3(PO4)2 (solid) + 6NaNO3 I then found the moles...
  16. S

    Concentration of salt in the tank

    Help... ? A 200 liter tank initially contains 100 liters of water with a salt concentration of 0.1 grams per liter. Water with a salt concentration of 0.5 grams per liter flows into the tank at a rate of 20 liters per minute. Assume that the fluid is mixed instantaneously and that this...
  17. S

    Solving a Differential Equation: Salt Concentration in a Tank

    can you help me ?? A 200 liter tank initially contains 100 liters of water with a salt concentration of 0.1 grams per liter. Water with a salt concentration of 0.5 grams per liter flows into the tank at a rate of 20 liters per minute. Assume that the fluid is mixed instantaneously and that...
  18. D

    Concentration for reactants: KMnO4+Sugar+NaOH

    I am given a topic: rate of reaction affected by change in concentration. We have to design a lab - come up with reactions and write a procedure KMnO4+Sugar+NaOH How much KMnO4 should I put in the mixture of Sugar and NaOH. And how much Sugar and NaOH should I start of with I am going to...
  19. M

    Finding the concentration in a solution

    I am doing a lab to find the concentration of copper in a penny. I am confused on how to find the concentration of copper in each solution I prepared. One solution for example: 2 ml of 0.080 M Cu(NO3)2 add 2 ml of concentrated ammonium hydroxide dilute solution to 50 ml Can someone help...
  20. J

    Of the same concentration buffers

    "of the same concentration" buffers Homework Statement In the question below what is the signifcance of them saying "of the same concentration" thanks http://www.thestudentroom.co.uk/attachment.php?attachmentid=113982&d=1321805514 Homework Equations The Attempt at a Solution
  21. M

    Stress concentration factors for hollow shafts under pure bending

    Hi everone, I am trying to make a rough estimate of fatigue life of a hollow shaft under pure bending at a particular load level.The hollow shaft has a shoulder fillet. The minuimum outer diameter is 69mm and the maximum outer diameter is 72mm with a transition radius of 6mm.The thickness of the...
  22. T

    Fresnel Lens Concentration Ratio

    Homework Statement Hey guys, I am part of a group building a solar oven. It will consist of insulated sides and a glass window on the top. Rather than using reflectors we want to salvage a Fresnel lens from an overhead projector to concentrate sunlight onto the glass window. Part of the...
  23. M

    How is weak acid concentration measured?

    Is a weak acids concentration determined from when it is in equilibrium, or if it hasn't dissociated at all? i.e. 0.100M CH3COOH. Would this be the concentration of CH3COOH during it's equilibrium: CH3COOH <-|-> CH3COO- + H+ Or just by itself? Thanks!
  24. G

    Unit problem with calculating the mass concentration of a particle

    Homework Statement We have to calculate the mass concentration for a particle size distribution. I'm just doing the first size range here, since once I get that the rest is just repetition. FYI, the particles are spherical. Size range (diameter) = 0.005-0.5 μm Average particle size...
  25. P

    Differentiate Primary Al & Eutectic Al in Al-17Si Alloys

    Hello, I am working on Al-17Si alloys. I have done some castings and in micro-structure I saw formation of Aluminium dendrites. I am unable to find out whether it is primary Al or eutectic Al. One way to find that is to find out Percentage of Si in the dendrites. But how do I do that? Is...
  26. G

    Thermo question on mean square of concentration

    This problem is from Callen. In the 1st edition it is 15.4-3. I am stuck on the last part of this problem. It also appears, in a slightly different form, in the second edition of Callen as problem 19.3-5. Homework Statement 15.4-3 Consider a small volume V within a two-component simple...
  27. M

    Solid State Physics- Finding concentration of donor atoms (Nd)

    Homework Statement Silicon at T= 300K contains acceptor atoms at a concentration of Na = 5*10^15 cm-3. Donor atoms are added forming an n-type compensated semiconductor such that the fermi level is 0.215 eV below the conduction band edge. What concentration of donor atoms are added...
  28. R

    Calculate Concentration of HCl & HOAc for Titration | NaOH & HCl/HOAc Mixture

    Hi, I'm in lab in which we have to titrate 0.09M NaOH into 25mL of 0.1M HCl/HOAc mixture. Homework Statement I need help on how to calculate the concentration of HCl and HOAc in the mixture. 0.09M NaOH 1st equivalence point = 14.3mL 2nd equivalence point = 26.9mL Difference of two...
  29. L

    Calculating concentration in molLl^-1 of a solution

    Homework Statement Determine the concentration in molL^-1 of a solution of sodium carbonate whoch contains 53g of sodium carbonate in 500ml of solution. Calculate the concentration of sodium and carbonate ions in this solution. Homework Equations no of mols= Mass/Mr mols= [ ] x vol...
  30. F

    Using Ksp to find the concentration

    Homework Statement 0.1100 mol AgNO3 translated into 500 mL of a solution containing 0.1000 moles of NaCl and NaBr 0.1000 moles. What are the concentrations of Ag+, Cl-, Br-, after equilibrium has occurred? Solubility product for AgCl: Ksp(AgCl) = 1,82*10^-10 Solubility product for AgBr...
  31. N

    How do you calculate the concentration of nucleotides from DNA?

    Hi, I was wondering if given the concentration of DNA, how does one calculate the concentration of nucleotides? Are they the same thing? Thanks. Nancy
  32. Y

    Calculation pH from concentration

    Homework Statement Shells of mussels are mainly of calcium carbonate. IUsually the shell is stable and its content is in equilibrium with the surrounding. Mussels need to build up or reduce their shell, however, for additional protection or during growth. They achieve this by changing the...
  33. F

    Band Bending & Donor Concentration in Semiconductors

    When a n-type semiconductor is brought into contact with a metal, then alignment of the chemical potentials of both systems leads to band bending within the depletion layer, e.g on the semiconductor side. does the amount of band bending (change of potential) also depend on the donor...
  34. S

    Change in concentration over time

    Homework Statement A tank with a capacity of 400L is full of a mixture of water and chlorine with a concentration of 0.05g of chlorine per liter. The chlorine concentration is to be reduced by pumping in fresh water at the rate of 4L/s. The mixture is kept stirred and pumped out at the rate of...
  35. FeDeX_LaTeX

    Chemistry - Concentration of Ions

    Homework Statement What is the concentration of ____ ions in a ___ mol dm-3 solution of ___?Homework Equations mass/molar mass = number of moles volume/molar volume = number of moles Not sure what other equations... The Attempt at a Solution I'm not understanding how this works. I have...
  36. S

    Where to Find Chlorophyll Concentrations for Different Water Types?

    Does anyone know of a book, chart, or website with different water types (clear ocean water, great lakes, ...) and their "average" or listed chlorophyll concentrations? Any sources would be greatly appreciated!
  37. K

    Schools Selecting Concentration for Grad School

    I am a prospective physics student currently attending a 4-year university. As I began to work in a lab in preparation for graduate school, I have been hearing cases of people with physics degree switch their graduate major/concentration and go to physics-related mathematics or engineering...
  38. M

    Equilibrium constant and concentration

    I am aware that the equilibrium constant, Kc for the reaction {aA}~~+~~{bB}~~~\mathop{\rightleftharpoons}^{k_f}_{k_b}~~~{cC}~~+~~{dD} is \frac{k_f}{k_b} = \frac{[A]^a [B]^b}{[C]^c [D]^d} Now my question is, are the stoichiometric coefficients a,b,c and d, written in simplest whole number...
  39. M

    Finding the concentration of X

    Homework Statement How do I find the Density of X (Part A) and how do I find the Concentration of X in a solution (Part B)? Part A: I have 4mL of X. The mass of 4mL of X is 10g. Calculate the density of X. Part B: I have 7g of X in 100mL of Water. Calculate the concentration of X. The FINAL...
  40. T

    Solving the Mystery of Deriving O2 Concentration in H2/O2 Mixture

    In a spherical vessel with a hydrogen H2 and oxygen mixture O2 it is stated in a problem that we can derive that the concentration of oxygen [O2] can be derived to be: P / 3RT. With P the total pressure, R the gas constant en T temperature? How on Earth is this possible? I thought the...
  41. morrobay

    Maximum concentration, molarity, of Carbonic Acid ?

    What is the maximum concentration, Moles/liter, possible for one liter of H2CO3 at STP. And how is that calculated ?
  42. S

    Concentration and pH Caculation of Titrations

    Homework Statement Calculate the volume of 0.116 M HCl(aq) required to neutralize the following solutions. all the hydroxide ions in 25.0 mL of 0.215 M KOH(aq) 1. What is the molarity of Cl - ions at the stoichiometric point? Homework Equations HCl + KOH --> KCl + H2O The...
  43. P

    Chemical Equilibrium and Concentration

    The reaction between hydrogen and fluorine has an equilibrium constant of 1.15x102 at a certain temperature. Given the reaction equation H2(g) + F2(g) -> 2HF(g), calculate the equilibrium concentration of HF after 3.00 mol of each component is added to a 1.500 L flask. I attempted solving it...
  44. U

    Stress concentration factor using combined static loads

    i want to design a machine which is capable of applying all three types of loads that is axial, bending and torsion. Using this application of static loads , I want to measure the stress concentration factor.
  45. A

    Calculation of concentration of a solution.

    How does one take into account the fact that volume of a solution increases upon dissolving solute? which volume should be taken as the net volume, the volume of solvent to start with or the full volume of the solution? Suppose I add 20gm of sugar in 100cc (or ml) of water. After sugar...
  46. G

    Schools Grad school help: choosing a concentration

    Grad school help: choosing a "concentration" Okay, so I will begin my graduate physics studies this fall. I'm incredibly excited, but very nervous, especially about the comprehensive/qualifying exams, but that's another story... I'm already in my early 30s, married, with a kid. Needless to...
  47. B

    Determining concentration by measuring pressure change

    Homework Statement Derive an equation how one can calculate concentration by measuring pressure change in a known volume. Known data: Pressure change dp/dt in a known volume V, volumetric flow rate F, total pressure p and temperature T. Homework Equations Probably ideal gas law...
  48. Ahmed Abdullah

    What enables cells to respond to changes in the concentration of a signaling ligand ?

    "In chemical signaling, adaptation enables cells to respond to changes in the concentration of a signaling ligand (rather than to the absolute concentration of the ligand) over a very wide range of ligand concentrations. The general principle is one of a negative feedback that operates with a...
  49. V

    Concentration, height, temperature

    Homework Statement In a large underground cave, the concentration of helium at the base is measured to be 1.00x10^-4. If the air in the cave is at a constant temperature of 10 degrees-C, what is the concentration of helium at the top of the cave, 300m higher? Answer: 1.03 x 10^-4...
  50. 3

    How Do You Calculate Molar Mass from Concentration Data?

    Hello! I'm completing a lab for chemistry and would like some help on the last bit figuring out concentration then converting to molar mass. I need to make a data chart with a line of best fit on it with the dependent/independent variables. I understand that concentration is on the X-axis and...
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