Concentration Definition and 550 Threads

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...

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...

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?

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...

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...

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?

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...

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) +...

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?

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.

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...

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...

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...

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...

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?

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...

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...

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...

[FONT=Arial]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...

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...

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...

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

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...

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?

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...

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...

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...

[SIZE="4"]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...

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...

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...

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...

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 =...

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...

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 +...

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...

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...

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...

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...

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...

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} =...

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...

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

Homework Statement 1. Estimate the concentration of oxygen in the Earth's atmosphere (in molecules / m^3), at room temperature and at sea-level, assuming the fact that oxygen comprises 21 percent of the Earth's atmosphere by volume. 2. If you were to place a perfect oxygen sensor of...

Homework Statement I need to know the concentration in ppm of a standard Fe2+ solution. (diluted) Here is the data I have. I have 0.1964 g of Fe solution the purity is 99.7% The original solution was the above # of g in 250ml water. 10ml of this was then pipetted into a 100ml volumetric flask...

Homework Statement What is the concentration of acetic acid in 250mL of a 100mM acetate buffer at pH 4.76? Homework Equations Henderson Hasselback The Attempt at a Solution I used the Henderson Hasselback equation. plugged in 4.76 for pKa. plugged in .025 for the concentration of...

SA + SB always give pH= 7 even if concentration of SA is a lot bigger than SB? let's say 10 M of HCl react with 0.1 M of NaOH, is the pH at equivalence point also 7?

Homework Statement A tank holds 10 L of pure water. Brine (unknown constant concentration) is flowing into the tank at 1 L/min. The water is mixed well and drained at 1 L/min. After 20 min, there are 15 g of salt left in the tank. What is the concentration of the salt in the incoming brine...

Hi guys, have been struggling with this exercise, could anyone give any help? thank you so much!

Hello- I have a diffusion profile, in which I plot the decrease in concentration versus distance of my sample. I am trying to find the increase in mass of the overall sample. How would I do this? I have integrated the function and am wondering what type of information that would supply...

Homework Statement For instance I have NaCl. I found a relationship between conductivity of NaCl in water and concentration of NaCl in the water. It's; conductivity is approx 0.5 concentration Is it correct that the change in concentration gives the number of ions? For example say I...