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. J

    Calculate CO concentration at high altitude

    Question: You are cooking in a tent at 17,000ft with outside air temp at -15F. The concentration of CO in the tent is 40ppm. Calculate the equivalent CO concentration in mg/m^3. First, I converted 17000ft to atm and got 501.5atm, which seems very wrong. Next, I converted -15F to...
  2. M

    Concentration Ratio of protein

    Myoglobin is a globular protein, with molar mass m ≈ 17,000g/mole. The buoyant correction typically reduces m to m' ≈ 0.25m. Calculate the concentration ratio of the protein at the top of a 4 cm test tube and that at the bottom. Here, m' stands for effective mass. I tried as below. I...
  3. A

    Radiation and gas concentration

    Does anyone know of any papers describing the interaction between radiation and gas. Specifically I am trying to find out is the relationship between PPM and the flux of the radiation. At what point do the two intersect to give a measurable response and does the interaction increase linearly...
  4. B

    Methods of determining concentration of solution

    I was wondering what the most effective (i.e. most accurate) methods are for determining the concentration of a known solution. In my specific case, I need to determine the concentration of a KNO3(aq) within 10% of the actual value. As of now, I have written up two separate procedures to...
  5. Entanglement

    Concentration of solids in equilibrium

    It's known that the concentration of solids don't affect the rate of the reaction since it's concentration is constant, I know that when the number of moles of a solid is increased the volume also increases the same so the concentration remains constant so the rate doesn't change, but when the...
  6. L

    Tunnel diode via dopant concentration

    Hi, all i am confusing about the characteristics of tunnel diode if the dopant concentration increased, how change the turn-on voltage ? does it depend on concentration ? if it depends on concentration, does the turn-on voltage increase when the dopant concentration increased ?
  7. F

    Biophysics: Concentration and Electric potential

    Homework Statement Consider a membrane which is permeable to a singly charged ionic species. If the concentration on one side is 25 times that of the other, what is the electric potential required to maintain a net flux of zero at 37C? Homework Equations I'm not sure: U = KQq/r flux...
  8. W

    Differential equation for concentration of gas in the atmosphere

    Homework Statement Hi everyone, I'm currently studying an online course on climate science and am a bit overwhelmed by the calculus. I have studied calculus to second year of college but that was a while ago and I'm very rusty. A few weeks ago I was a question to find the how long it would...
  9. Y

    Understanding Acid Concentration: Factors of Quantity and Ionization

    The concentrations of an acid depends on ________________. (a) Quantity (b) Ionization (c) Both It depends on what exactly we mean by concentrated? I have read a statement like hydrochloric acid having concentration 35-38% is considered concentrated while sulphuric acid having...
  10. H

    Something that bugs me about concentration

    This may sound ridiculous to the elite here, but if I had a bottle with 500mL of vinegar where 5% was acetic acid. If I removed 100 mL will there still be 5% acetic acid there then?
  11. A

    Equilibirum concentration in thermodynamics

    Are any of you here comfortable with thermodynamic calculations for heterophase fluctuations? Then please help me understand an important bit in my book (attached) I am doing a project on nucleation, i.e. the study of building of clusters of different atoms. In my book (attached part) it seems...
  12. A

    Diffusion: Concentration profile for point sink in infinite plane

    Hello, I have a certain diffusion problem I am trying to solve. Admittedly, I'm further behind on my math than I'd like, and have trouble setting it up properly, and no luck finding an exact analogue in the literature. I would like to solve for the time-dependent concentration profile...
  13. S

    Surface tension and concentration

    when we try to measure surface tension of different concentrated solutions of n-butanol with a tensiometer, we have to go from lower to higher concentration and not the other way around. what is the reason for that?
  14. S

    Shear Pin Stress Concentration V-Notch vs. U shape grooved in bending

    Can someone link a website or attach a picture of a chart distinguishing the differences between the stress risers in a shear pin (round circular shaft) with a V-notch groove versus if it was a rounded groove. I have been looking but can only find charts, tables and graphs for round circular...
  15. A

    Solubility Product, finding molar concentration

    Homework Statement If the 2.0 x 10-5 mol of Cu(IO3)2 can dissolve in 2 L of NaIO3, find the molar concentration of the NaIO3 solution. Ksp = 1.4 x 10-7 for Cu(IO3)2.Homework Equations The Attempt at a Solution Let y = [IO3-(aq)] present in the solution from NaIO3 Cu(IO3)2(s) ↔ Cu2+(aq) +...
  16. A

    Acid-Base low concentration of weak acid

    My textbook assumes that whenever K-constant of a weak acid is bigger than K-constant of water, the water should be a negligible source of H+ ions. However, how do we know that the concentration of weak acid could be too low and the H+ ions from water can actually have a significant effect?
  17. D

    3. concentration of sodium sulphate in the resultant solution?

    3. In an experiment, 2.00M sodium hydroxide solution was added to 20.0mL of 1.00M sulphuric acid until the acid was just completely neutralized. What is the concentration of sodium sulphate in the resultant solution? My final answer is 0.500mol/l. Am i correct.
  18. P

    Astronomy: abundance, concentration, density

    Homework Statement Hi. I feel like this is probably very basic. Basically, I'm trying to understand how surface density * concentration = abundance I'm reading about gas surface density in the galaxy and its relationship to star formation, gas ejection etc. And we are given an...
  19. Hyo X

    Doubling reaction recipe while maintaining concentration

    Say we are running a chemical reaction of some kind, in liquid, in a round bottom flask. We have a solvent, two reactants, a product, and the reaction is under stirring, reflux (volume maintained) and constant temperature. In my mind, if we simply double the volume of all the reactants...
  20. A

    MHB Drug Concentration After Multiple Dosages

    Suppose the concentration of a drug in the blood stream exponentially decays and is given by c(t) = a0e^-kt (0 is a subscript) where t is the time elapsed and a0 is the initial concentration after one dose. Further assume that doses of the drug are administered at time intervals of T. (a) After...
  21. M

    Density and molar concentration

    Hi,all. a book(j.p holman,heat transfer 7e,chapter 11) gives C (subindex)A = (ro) subindex A= P subindex A x M subindex A / Ro(universal) T but another book(stanley middleman,an introduction to mass and heat transfer) gives Ci=(ro)i/Mi. these are very different from each other.Ci is...
  22. F

    Material Science: Monovacancy Concentration

    Homework Statement The Monovacancy formation energy of a metal is 80 kJ/mol. Hence the monovacancy concentration (CV) at 25 degrees celsius is about: A)1.3x10^-13 B)9.5x10^-15 C).9 D)5x10^15 The Attempt at a Solution I know the answer is B but I don't know how to get to that. I...
  23. O

    Proton Concentration Cell: Finding Original pH with Initial EMF

    Proton concentration cell is made by connecting with Pt wire two acid-base solutions and measuring emf. but wire allows redox reaction, changing conc of H+ in each solution. how is original pH found- with initial emf reading?
  24. M

    Concentration of nitrogen oxide in air

    Homework Statement The relative compositions of the pollutants NO and NO2 in air are governed by the reaction NO + 1/2 O2 ⇔NO2 For air containing 21-mol% O2 at 25C and 1.0133 bar, what is the concentration of NO in parts per million if the total concentration of both nitrogen...
  25. K

    Stress Concentration Calculation

    Hi everyone, I wanted to know the stress concentration factor (Kt) for a cantilever beam with a fillet at the root with a point load applied at the end. Can I get the stress concentration factor if this beam is a 3D beam (thickness is comparable to length)? I had a look at Peterson's SCF...
  26. V

    Determining pH when given volume and concentration of a solution?

    Homework Statement I'm stuck on these two problems: A) IF you make a 50 mL of a 0.1 M Tris solution (in acid form), what will be the pH? B) If you add 2 mL of 1 M NaOH to the above solution, what will be the pH? Homework Equations pH = pka + log [A/HA] Hendersen-Hasselbalch The Attempt...
  27. alane1994

    MHB Finding Salt Concentration in a Tank with Limited Capacity

    A tank with a capacity of 500 gal originally contains 200 gal of water with 100 lb of salt in solution. Water containing 1lb of salt per gallon is entering at a rat of 3 gal/min, and the mixture is allowed to flow out of the tank at a rate of 2 gal/min. Find the amount of salt in the tank...
  28. P

    How to find the concentration of CO2 in 1M NAOH solution?

    I done the absorption experiment i.e absorption of CO2 from air using 1M NaOH .Can anyone please tell how to analyse the Liquid sample after absorption. I found the concentration of NaOH after and before the experiment,difference in Concentration gives the concentration of CO2.is it the...
  29. K

    Concentration of evanescent/surface waves

    Hello, At the interface between dielectrics and vacuum, there is always evanescent waves present (you can consider them as being generated due to total internal reflection of electromagnetic waves being generated by thermal fluctuation of charges inside the dielectric). In some cases you can...
  30. N

    Calculating Concentration in a Mixture of KNO3 and Fe3CN6

    hi,a basic question, i added 20 ml of 1M Kno3 with 20 ml of 2 mM of Fe3CN6. will the concentration of the two chemicals remain same in mixture?? if not how to calculate ... All i need to prepare a 20 ml of a mixture of 1M Kno3 and 2mM Fe3CN6... Thanks
  31. M

    What exactly is a concentration of acceptor in p-type semiconductor

    What exactly is a concentration of acceptor in p-type semiconductor? The symbol is Na. Lets say there's a Silicone, and it has 3 valence electrons, when it receives electrons (releases hole), it becomes negatively ionized, right? So that should mean Silicone is an acceptor, right? But what is...
  32. somasimple

    Final state of concentration cell?

    Hi, here is an example of a concentration cell http://www.jce.divched.org/jcedlib/qbank/collection/conceptests/echem.html 1/ The final state is assumed when concentrations are equal in each compartment, right? 2/ Graphic evolution of the voltage is a decreasing curve, right?
  33. G

    Solving Concentration of Ammonium Phosphate in mol/L

    Hey I have a problem on my hands, I'm trying to find the concentration of ammonium phosphate in mol/L. Equation: Excuse the badly written equation, I'm not quite sure on how to use subscrips/arrow signs on here. (NH4)3P04 --------------- 3NH4 + P04 Known Data: Mass of 3NH4 measured with...
  34. Esnas

    CO2 Concentration Tops 400ppm for the First Time in Human History

    This was described by Michael E. Mann,professor of meteorology at Penn State University. http://www.meteo.psu.edu/holocene/public_html/Mann/news/interviews.php Others have had readings that give similar results. "While scientists and environmentalists have used the daily milestone to...
  35. J

    Writing Common Ion Concentration in Buffer Eq. Expression

    Homework Statement What is the pH of a buffer solution created by combining 100 mL of 0.2 M acetic acid and 400 mL of 0.10 M sodium acetate? Ka= 1.8 x 10^(-5)Homework Equations 1.8 x 10-5=([C2H3O2-][H+])/([HC2H3O2]) The Attempt at a Solution I know what I'm supposed to do to solve this...
  36. S

    Effective atomic number for a mixture (with components concentration)

    Assume we have a concentration of any specific material (in mg/M). Let's say for example: Ag (Z=47) with concentration 10 mg/M in water (H2O, Z=7.42). How can I calculate the effective atomic number (Zeff.) for the silver-water mixture if the concentration of silver was 10 mg/M for example...
  37. A

    Semiconductor physics: Resistivity,mobility and concentration.

    Homework Statement If a sample of pure silicon at 300 Kelvin has a resistivity of 950Ωm, and if the electron-to-hole mobility ration is 3:1, with the electron mobility equal to 0.12m2V-1s-1, what are the intrinsic hole and electron concentrations? Homework Equations I know resistivity...
  38. J

    Determining new concentration?

    Homework Statement A solution 200mL solution has 1g/L of a solid dissolved in it. After boiling, there is only 136mL remaining. How much of the dissolved substance is left? I figured that if C1V1=C2V2, then if the concentrations were equal after calculation, i could the concentration...
  39. S

    Question regarding atomic weight percentage, and concentration

    One of the examples I was looking at had to do with diffusion of hydrogen in a Pb sheet. There is a constant concentration gradient applied, so the hydrogen is constantly diffusing. We are able to determine the concentration of the Pd matrix. We further know the atomic weight percentages of the...
  40. E

    Short Beam Stress Concentration

    Hi there Are anyone familiar with tables of stress concentration factors, or the like for short beams for different span/depth ratios. My beam is technically not a beam, but I would still like to estimate maximum bending stresses related to normal stresses caused by bending moment (sigma =...
  41. R

    What is a typical drug concentration in the body

    I'm trying to figure out a typical range of physiological concentrations for pharmaceutical drugs. I'm looking through papers that report candidate drugs administered to cell cultures; these papers report LD50 concentrations anywhere from 1 to 100 μM. I don't have any pharmacology experience so...
  42. 9

    Stoichiometry, concentration of solutions: Ba(OH)2 and H3PO4

    Homework Statement What volume of 0.0521 M Ba(OH)2 is required to react completely with 24.50 mL of 0.141 M H3PO4? Phosphoric acid is a triprotic acid. Answer: volume of 0.0521 M Ba(OH)2 required = 99.5 mL 2. The attempt at a solution 1. I begin by balancing the equation: 3Ba(OH)2 +...
  43. C

    Concentration of water vs. equilibrium

    Hi, I understand from calculation that the molar concentration of Pure water is 55.5 moles/Liter Then how come in equilibrium reactions when calculation the dissociation constant, we say that the concentration of water is 1 Molar? This seems like a huge difference to me? What is it I need...
  44. J

    Finding the best Equation for concentration substance

    Homework Statement I need to find the best equation possible for administration of a drug. I have found two types of equations; the first is by starting with a dose (d) and adding that same dose so that it builds up slowly over time. This is shown as the equation y(T)=de^(-kT) where T is the...
  45. Q

    Determining Concentration of a Tank (Using Linear Differential EQ)

    Homework Statement The problem states that we have a tank with a capacity of 400L filled with a mixture that has a concentration of 0.05g Chlorine per Liter. The concentration is reduced by pumping in pure water (zero concentration of chlorine), at a rate of 4L/s, and pumped out at 10L sec...
  46. N

    Differential Equations: Salt Concentration and logs

    Homework Statement A tank initially contains 180 gallons of water in which 8grams of salt are dissolved. Water containing 9 grams of salt per gallon enters the tank at the rate of 3 gallons per minute, and the well mixed solution leaves the tank at the rate of 1 gallon per minute. The...
  47. T

    Oxygen Flow Through a Concentration Gradient

    Hi guys First things first, I'll lay out the problem. I have a box of volume V containing a constant sink of oxygen (e.g. a candle or an animal); this box is sealed except for a smallish aperture of area, A and depth, L (the L meaning the walls of the box have finite thickness). After a...
  48. S

    Equilibrium concentration of majority and minority carriers

    Homework Statement Give the equilibrium concentration of majority and minority carriers and resistivity for Silicon which is doped with 3x10^{15} boron atoms/cm^{3} at 27°C. Homework Equations n_{o} = \frac{N_{d}-N_{a}}{2}+\sqrt{(\frac{N_{d}-N_{a}}{2})^{2}+(n_{i})^{2}} p_{o} =...
  49. D

    Question about fluid dynamics (calculating concentration)

    Hi all, I have a question about calculating the concentration of continuous air and carbon monoxide flowing through a pipe. If the gas cylinder originally has 20% CO and 80% air and it will be diluted by another gas cylinder of air, how do you account for temperature, pressure, and...
  50. W

    Max. concentration of radioactive particles in water

    Hi, does anyone know how I can find out the max. concentration of Cs-137 and Sr-90 in water?
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