Concentration Definition and 550 Threads

Homework Statement Niobium Nb has the BCC crystal with a lattice parameter of a= .3294 nm Find the planar concentrations of atoms per m^2 of the (100, (110) and (111) planes. The 100 plane has 1 atom on the plane (1/4 times 4) the 110 plane has 2 atoms on the plane and using...

I am not really sure how to find the original concentration of bacteria for my experiment. This is what i did: I made serial dilutions of 10^-2, 10^-4,10^-6, 10^-8 with stock bacteria. From 10^-4 dilution, I took out 2ml and inoculated into 20g potatoes + 180g buffer. Potatoes + buffer +...

Hi all, i have been assigned to study indoor air quality and car cabin air quality project. My Problem is: How to measure Carbon Dioxide concentration in that constant volume of air? (consider there will be changes in the concentration and i need to quantify or contrast it at least.)...

Hi all, We use often concentrations in chemical/biological experiments. It is expressed usually in mili/µ mole/cm3 or mm3 Is there a way to know the number of ions contained in a volume? Is there a way to know the number of ions (or density) on a surface knowing the concentration...

I can read for upto 3 hours before my brain feels saturated. It doesn't matter what it is I am studying after approx. 3 hours in and I can't take in any more. I take a break for 10 minutes but this doesn't seem to help much. When I come back I still feel saturated. How do I expand this? I would...

Homework Statement Square panel , elliptical hole, uniform pressure p in x direction. calc stress at end of minor axis. pt A L=40in p=10psi a=1in b=0.5 in t=0.2 in Homework Equations i know that stress at end will be max stress multiplied by stress conc. factor. bt i don't know...

So Kw = [H+][OH-] = 10^-14 is true all the time of water and aqueous solutions? When we add an acid, how does the OH- go down to maintain Kw? Is the OH- from the self-ionization of water helping to neutralize the addition of the acid? Thanks.

Dear All I will be grateful for any idea on how to measure electrochemically the charge carrier in an electrode say working electrode made of Al. Thank you from advance Shay

Which one has a greater concentration, 1 molar NaOH or 1 molal NaOH aqueous solution? for the answer Explain Why!

This is part of a longer problem, and probably obvious, but if I calculate this wrong, the rest of the calculations will be wrong too!... Question: Given the mass density, molar mass, and electrical resistivity of a substance at room temperature, how do you calculate the concentration of the...

I've been searching for an acceptable value for the charge density of indium arsenide; that is, the amount of charge per cubic meter. I have been unable to find anything. I'm working on a replication of the Hall Effect, and I need an accepted value for comparing my own results. I've searched...

I am trying to find the lowest concentration of hydrogen ions out of the following: 0.1 M HCl 0.1 M NaOH 0.1 M H2SO4 pure water I am having a hard time with the book and this...Thanks

Many of the chemical laws/concepts we deal with which relate some number to the 'quantity' of the reactants and/or products or the quantity of these substances among themselves, talk about 'activity'. For example, the law of mass action, or the Equilibrium constant. But I've seen that they...

Electron concentration in n-type semiconductor Homework Statement At T = 0 K, what is the electron concentration in a Si semiconductor that is doped with Phosphorus atoms at N[SIZE="1"]D=1017 cm^-3? At room temperature, what is the electron concentration of this semiconductor? The electron...

Hello, in a recent lecture on introductory engineering, our professor made reference to a stress concentration factor that pops up due to inconsistencies or changes in the shape of a material subject to a load. The introduction he gave referenced a method of stopping cracks by drilling a hole...

Homework Statement During the action potential, Na+ ions move into the cell at a rate of about 2.98×10-7mol/m2/s. How much power must be produced by the active transport system to produce this flow against a +25.2 mV potential difference? Assume that the axon is 11.7cm long and 19.6um in...

what is the concentration of blood plasma under normal conditions?? how do you even begin to answer this question HELP!

Hello everyone. Right now I'm learning about carbon electrical properties for my final assignment in college. But somehow i just can't find the intrinsic carrier concentration properties for carbon. I've found the graphics that show me the relationship between the intrinsic carrier...

Homework Statement 2 part question: part one is supposed to be a hint to part two. 1) find the general solution to the equation: dx/dt = x - x^2 2)A one gallon jug is half full of a liquid and half full of air. Additional liquid is being pumped in at a rate of 1/4 gallon per minute. If...

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

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.

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...

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...

[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.

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...

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...

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...

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...

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...

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

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...

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...

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...

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...

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...

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...

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...

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:

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?

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...

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...

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...

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.

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?

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.

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...

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...

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...

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 ...

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...