Questions tagged [concentration]

The concentration characterizes the composition of a mixture with respect to the volume of the mixture. There are mass, amount, number and volume concentrations. Related and within the scope of this tag are normality, molality, mole fraction/ratio, mass fraction/ratio.

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Column Dispersive Mass Balance analytical / numerical solution

Is there any analytical solution for the most common expression of column mass balance: $\dfrac{\partial C}{\partial t} + \left(\dfrac{1+\varepsilon}{\varepsilon}\right)\dfrac{\partial q} {\partial t} ...
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How to measure deuterium concentration in DDW at home when you try to DIY DDW from freezing process?

I tried to automatize the Deuterium Depleted Water (DDW) receiving from the freezing process, but the result can be reached only after deuterium concentration measurement. Anybody knows how to make it ...
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26 views

Moles of chlorine gas needed to make up an equivalent amount of saturated salt solution

I’m trying to solve a question about a saturated salt solution but am unsure of how to answer one of the parts or what it’s asking for. The Problem The maximum solubility of table salt (NaCl) in water ...
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Activity of a chemical species and compound

While reading a book on Instrumental analysis by Skoog, in appendix part they explain activity of a species. The relationship between activity of a species and it's molar concentration $[X]$ is given ...
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Can analytical precision be finer than a lower detection limit?

Can analytical precision be finer than a lower detection limit? For example, if the lower detection limit of an analytical method is reported as 0.010 ppm. Is it possible to have an analytical ...
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Change of OH concentration in water when base salt is added [duplicate]

I am wondering if there are certain approximations being made in the way textbooks instruct on how to calculate the change in [OH] of a solution after a weak acid/base salt disassociates. Their ...
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51 views

Calculating concentration of OH⁻ ions [closed]

Calculate concentration of $\ce{OH-}$ ions in $\pu{0.66 mol L^-1}$ solution of $\ce{NH4+}.$ I think that there might be something missing, as the only law I have for this kind of problems is $$[\ce{...
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How does pH depend on temperature, when taking into account volume expansion?

Since autodissociation of water is endothermic, increasing the temperature will drive the following equilibrium to the right, which has the effect of increasing $[\ce{H+}]$: $$\ce{H2O <=> H+ + ...
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Finding initial amount of ammonia using equilibrium constant and amount of nitrogen gas

Question When an amount ammonia is added at $\pu{600 K}$ in a $\pu{1 L}$ container the following reaction takes place: $$\ce{N2(g) + 3 H2(g) <=> 2 NH3(g)}$$ The equilibrium constant $K_c = 4.20$...
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Energy and impurities balance for adsorption with a fixed bed (with description)?

Do you have any suggestion where to look for a source of information about energy and impurities (component) balance for adsorption of mixture CO2/H2O in fixed bed? I have looked into many articles /...
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How did the temperature in the solution with a lower concentration of CuCl2 increased in a faster rate?

My lab assignment is about the reaction between $\ce{CuCl2}$ and Aluminium and we tracked the temperature of the solution every 15 seconds and we needed to make our own experiment to check how ...
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Confusion about Titration Formula [closed]

When performing a titration of a monoprotic acid and a monoprotic base, water can not be added to the titrant but water can be added to the analyte. To prove this statement to myself, I decided to ...
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The pH of a drop of water containing ammonia

Presented with the following equations: What would the $\mathrm{pH}$ of a drop of water be, while in equilibrium with $\ce{NH3(g)}$ at a concentration of $\pu{150 ppb}$? $$\ce{NH3_{(g)} + H2O_{(l)} &...
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What is the easiest way to concentrate a solution without causing it to hydrolyze?

I’ve been working with iron acetate solutions in dilute acetic acid (vinegar) and I’ve been running into a problem. Every time I try to boil off the solvent the solution hydrolyzes to form iron oxides....
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A gram of salt added to pure (distilled) water introduces around $2 \times 10^{22}$ ions? [closed]

I am currently studying Practical Electronics For Inventors, Fourth Edition, by Scherz and Monk. Chapter 2.5.2 Resistivity and Conductivity, claims the following: Adding an ionic compound in the ...
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Did I accidentally create phosgene gas [closed]

I accidentally mixed bleach and acetone trying to remove hair dye stains from my shower wall. The mixture turned orange when the bleach and acetone touched. Could I have created phosgene gas ...
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Change in concentration when acids are diluted

I came across this formula to calculate the resultant [H]+ concentration when two weak acids are mixed (Both acids of equal volumes are mixed together). The only problem i have with this is that, we ...
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How to calculate the concentration of reagents and products from Kc? [closed]

In the synthesis of ammonia at equilibrium constant is $K_c = 1.2$ according to the reaction: $$\ce{N2 (g) + 3H2 (g) <=> 2NH3 (g)}$$ If an equilibrium is proposed based on initial ...
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Determining mol/L at STP from volume and mol fractions in a CFD program

I'm using some CFD software and the outputs are a bit unusual so I thought I would double check my understanding on how to do these conversions. The data available per cell is: cell volume, particle ...
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Reaction order of a reaction with catalyst

I am given the following $\ce{H2O2 -> H2O + 1/2 O2}$ (catalysed by $\ce{KI}$) There are two solutions. $[\ce{H2O2}]$ is the same in both solutions but $[\ce{I-}]$ is $\pu{0.01M}$ and $\pu{0.005M}$,...
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How does the derivative of concentration make sense?

First of all, I would like to make clear that I don't know very much about chemistry, and I'm not very sure this is the right place on Stack Exchange for this question, so please let me know if it ...
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Total Dissolved Solids and Alkalinity [closed]

I need to calculate total dissolved solids (TDS) of various groundwater samples from chemical analyzes. I have concentrations of ions/molecules in mg/L. I’ve found various formulas to calculate TDS ...
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How many significant figures should I report calculating volume concentrations? [closed]

Let's say a $\pu{300mL}$ solution of $\ce{CuCl_2}$ was diluted to $\pu{900mL}$. I am then asked to calculate the concentration of the new solution. My solution to the problem is as follows: $$\begin{...
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Activities and molar concentrations

I would be really happy if someone would clarify the term "chemical activity" and its implications for me, and also how it is related to the concept of molar concentration. My textbook fails at ...
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How to calculate the volume of HNO3 needed to produce a specific concentration? [closed]

How much $\pu{cm^3}$ of $\ce{HNO3}$, $\omega_{\ce{(HNO3)}} = \pu{63}\%$ with density $\ce{HNO3}$ of $\pu{1.4 g cm-3}$ do we need to create $\pu{500 cm^3}$ of solution whose $c = \pu{0.2 mol dm-3}$? I ...
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How can I make AgNO3 more basic? [closed]

Is there anything that I can add to the AgNO3 solution that will make it more basic without forming a precipitate such as reacting with OH or HCl? Please be more specific and give an example.
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Protons and osmotic potential

In a hypothetical enclosed membrane only permeable to water (including hydronium), where inside the pH is lower than the outside, would water move inside?
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Creating 1L of 1000 ppb stock solution of Pb2+

I’m testing on samples that require a concentration of 1000 ppb (or 1 mg/L) of Pb 2+. My first thought was to simply dissolve 1 mg of Lead nitrate in 1 L of deionized distilled water to create 1 L of ...
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Protein concentration in the cell from concentration in nucleus and cytoplasm [closed]

I have two quantities obtained by simulation. One represents a protein concentration in the nucleus, say $X_N$ and the other the same protein concentration in the cytoplasm , say $X_C$. I have real ...
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1answer
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Discrepancy between the apparent volume of the solution and the volume of the solute arising from the definition of solubility

I have solubility $s$ given in $\pu{g/mL}.$ I understand this as mass of solute $m$ divided by volume of solvent $V.$ But how about the volume of the resulting solution? I read online I should pour ...
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Active masses of solids and liquids [duplicate]

In the calculation for equilibrium constant, we take the active mass of solids and liquids as unity. Intuition tells that more amount of a solid reactant should result in more product being formed, ...
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Topical hand sanitizer production question from tutor; Concentration and dilution of chemicals of known concentrations [closed]

The question is as follows: You are in charge of making hand sanitiser based on the WHO Guide to handrub formulations, FORMULATION 1 Final concentrations: • Ethanol 80% (v/v), • Glycerol 1.45% (v/v)...
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2answers
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Concentration when done wrt mass or volume [closed]

I have a question asked in jee main 2020. 10.30 mg of o2 is dissolved into a litre of sea water of density 1.03 g/ml. The concentration of o2 in ppm is? Well I know that ppm is generally possibly ...
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1answer
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Too much leftover in zinc sulfate reaction?

I'm doing a reaction of zinc metal and sulfuric acid to get zinc sulfate. I've been trying to learn the chemistry lately so I tried to measure out correct molar amounts. My understanding from the ...
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110 views

Why is measurement in molarity preferred over molality?

NCERT Chemistry Part 1 states that: "The osmotic pressure method has the advantage over other methods as pressure measurement is around the room temperature and the molarity of the solution is used ...
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Concentrating Isopropyl alchohol using non-iodized salt

I am using 99% isopropyl alchohol to clean soldering flux residues for my electronics projects. Due to a certain viruse running amok in the world today, I am not able to get from my usual supplier. I ...
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What effect is on the rate and rate constant when concentration or temperature increases/decreases?

I have a few questions regarding rate and rate constant. I am wondering what effect certain concentrations, temperature, etc., has on rate and rate constant. Would be of great help if you can clarify ...
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Hydrochloric acid substitute in an Iron-gall ink solution

Recently I started experimenting with making my own ink to be used in fountain pens. I was wondering if hydrochloric acid in an iron-gall ink is used to prevent sediment ONLY by lowering the pH of ...
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Why is the equilibrium constant for a Daniell cell not equal 1?

Using the equation $$RT\ln K = nFE,$$ the equilibrium constant $K$ for a Daniell cell at standard conditions can be found as $$K = \exp\left(\frac{2 × 96500 × 1.1}{8.3145 × 298.15}\right) = \pu{1....
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Can the direction of electron flow in a voltaic cell be reversed? [closed]

I am wondering if the direction of electron flow in a voltaic cell be reversed such that the cathode becomes the anode and vice versa. I understand this is not possible for two standard half-cells, ...
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216 views

Nernst Equation for Lithium ion battery

For electrochemical cells we know $$ \Delta G = \Delta G^{\ominus} + RT\ln Q=- RT\ln Keq + RT\ln Q=-nFE $$ So for lithium ion batteries the reactions are Cathode $$ \ce{CoO2 + Li+ + e- <=> ...
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Can I determine the rate law order from stoichiometric coefficients?

I've read in two books, and seen in three separate videos courses, that you cannot determine the rate law order from stoichiometric coefficients. Then, I have seen homework and "practice" problems ...
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I was wondering if anyone could provide me with a method to solving as I do not know what I am doing wrong after multiple attempts?

A portland cement sample contained 20% SiO2 by weight derived from two silicate compounds, SiO2.2CaO and SiO2.3CaO that are present in the cement in the mole ratio 3 : 4. Determine the percent by ...
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If I dissolve 0.1M of CaCl2.2H2O in water, do I get a 0.1M CaCl2 solution? [closed]

If I dissolve $\pu{0.1 M}$ of $\ce{CaCl2.2H2O}$ in water, do I get a $\pu{0.1 M}$ $\ce{CaCl2}$ solution?
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Liquid fertilizer nutrient values - % weight by weight or % weight by volume?

I was convinced that liquid fertilizer labeling use the % weight by volume convention. However now I bought a magnesium-sulfur based additive. The label clearly uses % weight by weight. Weight by ...
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Molarity of two solutions

Question: Two solutions of ethanol marked as X and Y are labeled as 25% ethanol by mass and 25% ethanol by volume respectively. If the density of solution Y is 0.789 g/mL and that of solution X is 0....
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Setup for Sensing change in concentration of NaCl

I am making a sensor to sense the change in concentration of NaCl. My background is in electronics and chemistry is not my strong area. I got some screen printed electrodes, with Silver (Working ...
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Is the active mass of every solid and liquid taken to be unity?

I learnt from my textbook and the question/answer - Why is active mass of a pure solid or liquid always taken as unity? that active mass of a solid or liquid is taken to be unity as: $$[A]=\frac n V=\...
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How much of Sodium dichloro-s-triazinetrione dihydrate should I use to replace bleach? [closed]

I am trying to determine how much sodium dichloro-s-triazinetrione dihydrate powder I should add to water to create a dilution that can be injected into my water supply to react with the Hydrogen ...
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What exactly is the requirement (in terms of saturation) for a reaction to be at equilibrium? [closed]

A saturated solution is a solution that contains the max amount of solute able to be dissolved. However, can't a solution still be at equilibrium if you add more solute to a saturated solution as long ...

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