Concentration Definition and 583 Threads

Homework Statement At 300 K, kp = 1.5 x 1018 for the reaction 3NO --> N2O + NO2 If 0.030 mol of NO were placed in a 1.00 L vessel and and equilibrium was established, find the equilibrium concentrations of NO, N2O and NO2. Homework Equations The Attempt at a Solution First, I...

Is it possible to find out the relative concentration of c02 by looking at the emission or absorption from a hot gas, T = 1000K, containing among other C02? What I want to find out is if the emission depends linearly on the concentration. (in the IR region) What theoretically equations may I...

Hi! In my lab we're preparing a toxicity bioassay using nitrate (NO3-) as the test toxicant. The tests we're doing are range-finding tests, to help determine the lethal concentration (LC50) for that species with nitrate. We are following the lead of another work...

Homework Statement hey guys I've got a problem, could you tell us where i went wrong Lithopone is a brilliant white pigment used in water-based interior paints. It is a mixture of barium sulfate and zinc sulfide produced by the reaction BaS(aq) + ZnSO4(aq) ZnS(s) + BaSO4(s) What mass of...

Homework Statement You are provided with a solution of hydrogen peroxide which is known to be approximately ‘100-volume’. Plan two experiments that would enable you to determine the exact concentration of H2O2 in mol dm-3, in this solution Homework Equations 2H2O2 (aq)...

To determine the Fermi Energy for metals such as sodium, copper, gold, ect., one needs the Electron Concentration per cubic meter for the metal of interest. I am curious how this quantity can be determined. I referred to my physics textbooks and did search the Internet. However, the...

Homework Statement You are provided with a solution of hydrogen peroxide which is known to be approximately ‘100-volume’. Plan two experiments that would enable you to determine the exact concentration of H2O2 in mol dm-3, in this solution. One of your experiments should involve a redox...

Homework Statement To determine the Fermi Energy for metals such as sodium, copper, gold, ect one needs the Electron Concentration per cubic meter. Homework Equations How is this number determined? The Attempt at a Solution My textbook does not give me this information and...

Homework Statement 2 solutions of C12H22O11 are mixed. Solution A is .150M with density of 1.05 g/mL. Solution B is 10% C12H22O11 by mass with density of 1.03g/mL. 100 mL of solution A is mixed with 100g of B. What is the mole fraction of C12H22O11 in the mixed solution? Homework...

Homework Statement CH4 (g) + H2O (g) <- -> CO (g) + 3 H2 (g) .2 M CH4 and .2 M H2O are added to an empty 4 L sealed vessel at 1400 K. When equilibrium is established, the concentration of H2 is .444 M. Calculate Kc... which I did and got 4.8 which is the given answer. The real problem I...

Homework Statement Insects do not have lungs as we do, nor do they breathe through their mouths. Instead, they have a system of tiny tubes, called tracheae, through which oxygen diffuses into their bodies. The tracheae begin at the surface of the insect's body and penetrate into the...

Homework Statement Find the required mass of Al2(SO4)3.18H2O (molar mass = 666 g/mol) to prepare 50 mL of an aqueous solution, concentration = 40 mg of Al3+ per mL The Attempt at a Solution 0.04 grams of Al3+/1mL = x g / 50 mL x = 2g I think this is the required mass of Al3+, now I...

Earth's atmosphere has roughly four molecules of nitrogen for every oxygen molecule at sea level; more precisely, the ratio is 78:21. Assuming a constant temperature at all altitudes (not really very accurate), what is the ratio at an altitude of 10km? Explain why your result is qualitative...

*urgent* Finding unknown acid concentration Homework Statement Construct an experimental procedure in in order to determine the unknown concentration of an acid. Be sure to describe the standardization process. Homework Equations The Attempt at a Solution I think a viable...

% by mass concentration Homework Statement An aqueous CaCL2 solution has a vapor pressure of 80.8mmHG at 50 degree C . The vapor pressure of pure water at this temperature is 92.6 mmHG . What is the concentration of CaCl2 in mass percent? Homework Equations % by mass = mass solute/mass...

% at. concentration unit? hi all i wonder if someone can help me to know about the concentration measurement unit (% at. ), what does that mean?? thanks

Homework Statement How many mL of 50.0% by mass HNO3 solution, with a density of 2.00 g/mL is required to make a 500 mL of a 2.00 M HNO3?Homework Equations initial Molarity X initial Volume = final Molarity X final VolumeThe Attempt at a Solution (50 g HNO3)(1 mL/2.00 g)(0.001 L/1 mL) =...

Homework Statement Hello. I have a lab procedure that I am supposed to write, and since my teacher is on a two-week sick leave and the substitute does not know anything, I seriously need some assistance. Please note that for the following problem, a titration is NOT allowed. It must be...

I solved an assignment problem and I came to the conclusion that the % ionization of a strong acid decreases as the initial concentration of the ionized acid is increased. I don't fully understand why this is..? Any clarification would be greatly appreciated! Thanks in advance!

Homework Statement If 0.12 g of magnesium hydroxide Mg(OH)2 is dissolved in sufficient water to make 500. mL of solution, what is the hydronium ion concentration in the solution? (Assume that all of the magnesium hydroxide dissolves.) Homework Equations pH = -log [OH-] pOH = -log...

Homework Statement The phosphoric acid in a 100.00 mL sample of a cola drink was titrated with 0.1029 M NaOH. The first equivalence point was detected after 13.34 mL of base added, and the scond equivalence point after 28.24 mL. Calculate the concentration of H2PO4- in mol/L. (Hint: if only...

lmax or 1max ?? Homework Statement I have a graph of concentration vs Absorbance like below, for PNP. http://img512.imageshack.us/img512/2614/pnpgraphexfa7.jpg problem is that I have to find the unknown concentration, so I use the graph to determine that. The equation to find it is...

I was wondering if someone could help me understand how to measure different concentrations of dye in water. My experiment is to test out different concentrations of dye, that will be able to change the color of a flower. I didnt want to use the simple way of putting 1 drop, 2 drop, etc...in...

Homework Statement suppose that for a 10 mL sample of Ba(OH)2 solution, the mass of the cubicle with precipitate is 17.539g and the mass of the empty cubicle is 17.410g. calculate the concentration of the Ba(OH)2 solution from this data. Homework Equations The Attempt at a Solution

Homework Statement given a 10.0mL sample of Ba(OH)2 solution, calculate the concentration of the solution if it took 7.85mL of a .102 M H2SO4 to reach the equivalence point Homework Equations The Attempt at a Solution

Do any of you have experience with medication designed to increase concentration, directly or indirectly? I've continually pondered if this is something I should be seriously interested in. Anti-depressants have taunted me for many years, but I've managed to get by without them out of fear of...

I am performing an experiment where I am spiking my product with various % of CTAB. I have made stock solution of 2% (w/v) CTAB in 40 mM NaCl. I also need to make sure that I maintain the NaCl conentration at 40 mM. The product that the stock solution is being added to doesn't have any NaCl...

Homework Statement 6CO2 + 6 H2O → C6H12O6 + 6 O2 Now suppose the above reaction is allowed to proceed in both directions, and has reached equilibrium. How would increasing the concentration of oxygen change the concentrations of carbon dioxide and sugar? Homework Equations The Attempt at a...

Homework Statement A 20.00 ml stock sample of HBr is diluted to 50 mL. If 18.76 ml of 0.1345 M KOH was required to reach the equivalence point, what is the concentration of the stock HBr solution? Homework Equations KOH + HBr --> KBr + H20 M = conc. = mol./L n = V * conc. The...

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!

Hello all! I am a 3rd year Electrical Engineer, and it's almost time for me to select which concentration I want to go under. Ideally, I would like to concentrate in both Communications and Computers, but for some reason my university only allows me one. I can't seem to decide between the...

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 need to determine the concentration of 100cm3 of aqueous sodium hydroxide solution (approximately to 2 mol dm-3) using 200cm3 of sulphuric acid by calorimetry (Enthalpy of neutralisation). I am using E=mct. As its an exothermic reaction i will be finding the temperature difference. From...

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 ND=1017 cm^-3? At room temperature, what is the electron concentration of this semiconductor? The electron mobility...

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...