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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Viscosity and concentration of solutions

I will need a fluid around a specific viscosity, using a mixture of water and something like sugar. Is there a way to calculate viscosity based on concentration?
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Find pH and concentrations of bicarbonate and carbonate in the rain droplet

The concentration of hydrogen ions in a rain droplet is $\pu{0.000141 M}.$ Calculate the $\mathrm{pH},$ the concentration of both bicarbonate and carbonate in the rain droplet by assuming that the ...
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How to distinguish mass concentration and density?

I am writing a proof where I have to mention both with density and of a material and mass concentration (mass/volume) of a material. I am using the letter $\rho$ to represent density, and I didn't ...
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33 views

What does pH of NH3 solution refers to?

I was introduced with an exercise which asks to find $K_\mathrm{b}$ of $\ce{NH3}$ when the $\mathrm{pH}$ of $\ce{NH3}$ solution with concentration $M_1$. Well, in order to solve it, I used the fact ...
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Doubts Regarding Activators for Non Sulphide Compounds in Froth Floating Method of Concentration of Ore

I was recently going studying about Metallurgy and read in a book namely Concise Inorganic Chemistry by J D Lee that the process of froath floating can also be applied to ores such as Malachite (CuCO3....
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How do I calculate the correct sample concentration for my measurements?

I will measure absorbance for measurement of protein concentration. The sample solutions are prepare in serial dilutions to the volume of 100 uL to obtain a certain concentration of the protein in ...
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23 views

What is the equation that describes the variation in concentration of an inhibitor in an heterogeneous catalysis?

I find myself in quite a pinch: I have to sustain a Chemical Physics exam, and I know for a fact that the professor often asks this particular question: Suppose that we have both a reacting species ...
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68 views

Density and concentration of hydroiodic acid [closed]

I weighted my hydroiodic acid sample: 25 ml weight 34.1 g, so the density is about 1.364 g/ml. I want to know its concentration based on density. Does anyone have the corresponding density chart?
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Arrhenius equation using concentration

I've been conducting some experiments to determine the temperature dependence of a reaction. To do this, I've been conducting the experiments at different temperatures and generated a graph of $\ln{[\...
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56 views

Why does mixing two solutions decrease the concentration of the solutes?

The irreversible liquid reaction $$\ce{A + B -> C + D}$$ follows an elementary rate law and is carried out isothermally in a plug flow reactor (PFR). The volume of the PFR is 500 litres....
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What does “at%” mean and how it differs from “mol%”?

Sorry if my question is a bit obvious, but for some reason I'm getting confused with the percentages in this question: Concentration of $\ce{A}$ is $\pu{80 at\%}$ and concentration of $\ce{B}$ is $...
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Molarity of pure water [closed]

The molarity of pure water is 55.5 M at which temprature is obtained this value? Further, you will come across that 1000 mL = 1000 g (for water only, but at which temprature?)
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How does molarity change with dilution?

If I have a 1M solution of NaOH and I want to obtain a 0.2M solution. Then according to the formula $$ {M_1V_1 = M_2V_2}$$ I would get the answer as 200 mL. In my textbook they have said that "Thus, ...
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Reconciling these different solubility values

In a review article [1] on the solubility of CaCO$_3$(calcite), the solubility is reported to be on the order of 1 gram/litre. Since CaCO$_3$ has a molar mass of about 100, this solubility is ...
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How do I convert salinity measured in mg/L Cl into parts per thousand as NaCl?

I have collected water data using a refractometer that records salinity in ‰ (parts per thousand) as $\ce{NaCl}$. I want to compare my data to other data but every journal article I read has the ...
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What is the final molar concentration (molarity) of the nitrate ions in the resulting solution?

A chemist mixes 16.3 mL of 1.23 M sodium nitrate with 6.28 mL 0.823 M solution of calcium nitrate. What is the final molar concentration (molarity) of the nitrate ions in the resulting solution? What ...
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Calculation of resultant pH

A solution with $\mathrm{pH}=4$ is mixed with a solution with $\mathrm{pH}=10$ in equal volumes. Calculate resultant $\mathrm{pH}$. Please note both solution consists of strong acids and/or bases i....
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Determine direction of mass transfer

For part a) I don't really know what to look at. Diffusion occurs from low to high concentrations so by looking at $t_1$ I would say that the direction of the mass transfer is from phase II (organic ...
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42 views

Neutralisation Reaction Confusion

What will happen when $\pu{1 mol}$ of $\ce{H2SO4}$ reacts with $\pu{1 mol}$ of $\ce{NaOH}$? Will $\pu{1 mol}$ each of $\ce{NaHSO4}$ and water be formed? Or will $\pu{0.5 mol}$ of $\ce{H2SO4}$ will ...
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What Value of Purity Do We Substitute in the Formula C=10PD/M

In the the formula $$C = 10P\frac{D}{M}$$ $C$ is the concentration of a substance in a solution, $P$ is the percent concentration (purity) of the substance, $D$ is the relative density of the ...
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pH of strong acid weak acid mixture [closed]

Question: $\ce{H2S}$ ($\pu{0.1M}$; $K_\mathrm{a} = 1.2×10^{-20} $) and $\ce{HCl}$ ($\pu{0.3M}$) with same volume are mixed together. What is the resultant $\mathrm{pH}$? My approach: Let the volume ...
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Common ion effect

Let $\ce{HA}$ ($x$ molar) be a strong electrolyte and $\ce{HB}$ ($c$ molar) — weak electrolyte. As $\ce{HA}$ is strong electrolyte, it dissociates completely: $$ \begin{array}{lcc} \ce{&HA &-&...
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Sample: How to calculate mass of nanopaticles with given density and Vol % [closed]

I'm trying to calculate the wt% and the mass of the nanoparticles in a ferrofluid solution. Attached is data from the supplier: ...
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Finding molarity of hyposulfite solution used in titration

$\pu{0.1 g}$ of $\ce{KIO3}$ is treated with excess $\ce{KI}$ solution. The liberated iodine required $\pu{44 ml}$ of $x$ molar hypo solution. Calculate the value of $x$. I have used the equivalent ...
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1answer
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Which conductivity law should I use to calculate the conductivity of a solution with high/low concentration?

I have a set of NaCl solutions with concentrations ranging from 0.05 M to 0.1 M. I have been trying to calculate the conductivity of these solutions and compare the obtained values with the ...
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Given Kd find equilibrium concentrations of the reactants

$$\ce{Biotin + Avidin → Complex}$$ Biotin is a vitamin derivative that binds extremely tightly to avidin (a protein found in egg white) with a $K_\mathrm{d}$ of $\pu{1e-15 M}$. If you make a ...
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Adjustment of calcium, magnesium and alkalinity in drinking water?

It's been a long time since I did any molar chemistry in school and despite doing a lot of reading on the subject this week, I am making a mess of some basic calculations. I hope that someone who ...
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44 views

Volume of 0.5 M HCl needed to make a 10 % 500 ml solution

What volume of $0.5\ \mathrm M$ HCl solution is needed to prepare a $500\ \mathrm{ml}$ $10\ \%$ concentration solution, whose density is $1.05\ \mathrm{g/cm^3}$. I've started off with finding the ...
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Molar flux through membrane

Consider a liquid of pure $\ce{A}$ covered by a composite membrane through which the vapor of $\ce{A}$ is diffusing. The membrane consists of two layers of thickness $l_1$ and $l_2$. The diffusion ...
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2answers
74 views

Molarity Numerical on Mixing Solutions

If 3 L of 1 M NaOH solution is prepared by mixing properties of stock solutions of $x$ L of 2.5 M NaOH and $y$ L of 0.4 M NaOH and no water is to be used, find $x : y$. My attempt: $$3 = 2.5x + 0.4y$...
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Equilibrium concentration of point defects in solids at sufficiently elevated temperature

Equilibrium concentration of point defects in solids is defined as $\chi=\exp(\frac{\Delta s}{k_B})\exp(\frac{-\Delta h}{k_BT})$. At high temperatures, may be even higher than melting temperature of ...
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How do I calculate the hydronium ion concentration if I know the strontium hydroxide concentration?

This is my first question so I would appreciate feedback on how to ask better questions. Forgive me if I don't know how to properly format math/chem. The guide is confusing. I was taking a practice ...
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1answer
63 views

IUPAC Recommendations for Concentration Units (ppb, ppm)

In a recent interesting post, (Is 1 ppb equal to 1 μg/kg?) it was pointed out that IUPAC advises to abandon parts per million, parts per billion quantities and instead it suggests to employ micromole/ ...
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Is 1 ppb equal to 1 μg/kg?

In an article I recently submitted, a reviewer asked that I provide a concentration in μg/kg instead of ppb (parts per billion), and mentions that the later is not correct. I am not a chemist, and I ...
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Preparation of Copper (II) Sulfate Pentahydrate Solution

how would you make a solution of Copper (II) Sulfate Pentahydrate to achieve 150, 200, 250 and 300 mgL−1 concentration of copper? I do not have the anhydrous version of the solute. Also, when I ...
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1answer
45 views

Changes over time in sodium hydroxide concentration in a hot water bath used for pretzel manufacture

I make soft pretzels using a hot (190 °F) and dilute (2-4% w/v) sodium hydroxide solution. The bath is kept hot in a open-top stainless steel vessel like a stockpot. I make my pretzel dough and dip ...
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Types of concentration units

I would like to ask about a concentration unit. What does it exactly mean when stock concentration of something is, for example, 5X? Thank you in advance!
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177 views

What is the concentration of H2 for the equation H2+I2=2HI if the equilibrium constant is 64 and the initial concentrations are both 1.9

So for this, I set up the equation = $$64= \frac{(x)^2}{(1.9-x)^2}$$ I took the sqrt of both sides and got $$8=\frac{x}{(1.9-x)}$$ So then I did $$8(1.9-x)=x$$ And simplified I got $$15.2=9x$$ ...
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Is there a name for this algorithm to calculate the concentration of a mixture of two solutions containing the same solute?

There is an algorithm called "Mischungskreuz" (German for "x of mixing") that is sometimes taught as a shortcut to figure out the following problem: You have two solutions that contain a solute at ...
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How do I make 100 milliliters of 100mM H2O2 using 3% H2O2? [closed]

I need to make 100 milliliters of 100mM H2O2 using 3% H2O2. Do I: add X milliliters of distilled water to the 3% H2O2? How many ml? or add X milliliters of 3% H2O2 to the distilled water? How ...
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Emergence of Lognormal distribution for the concentration of chemical compounds

I'm currently reviewing the literature about lognormal distributions describing/approximating the variability of a given chemical compound across different cells/ samples etc etc. The main argument ...
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Is 99% Isopropyl Alcohol sold in stores really 99%?

My understanding is that an azeotropic mixture of isopropanol and water is 91%. This makes sense as to why there are so many brands of rubbing alcohol sold at 91%. There are also some sold as 99%, ...
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Help required for the calculation of moles [closed]

If 4.5ml of yeast prep + 0.5ml of 0.25 M glucose is separated into 2ml in 2 similar flasks. How many micromoles of glucose are there in one flask? Using M1V1=M2V2 (0.5ml/1000)*0.25M = M2 * 2ml = 0....
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how to calculate the initial concentration of NaOH in a mixture? [closed]

I have doubts about how to find the equation for the calculation of the initial concentration of $\ce{NaOH}$. I have the following information: in the kinetic study of a reaction, We measure $\ce{20....
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Direction of mass transfer in two film theory

In an extraction process compound A is transferred from one solvent to another solvent. The two solvent may be, for example, water and dichloromethane. These two solvents are immiscible and when ...
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Diffusion across a thin film

Given this concentration profile, I am to (1) determine at which side substance A will diffuse out of the membrane and (2) chose one of the following profiles below which represents the concentration ...
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1answer
93 views

Calculate pH of a buffer solution

Calculate the pH in a buffer prepared from $\pu{50 mL, 0.30 M}$ formic acid ($\ce{HCOOH}$) and $\pu{30 mL, 0.40 M}$ sodium formate ($\ce{HCOONa}$). My way of solving: $n_{\ce{HCOOH}} = 0.05 \times ...
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1answer
45 views

What are some ways to measure sugar concentration of fruits? [closed]

I've tried to do titrations using the quantitative Benedict's Solution and it was difficult to use as I do not have a way of keeping a constant temperature. I am currently using a Polarimeter to find ...
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841 views

Why proton concentration is divided by 10⁻⁷?

I am reviewing the book Biochemistry Concepts and Connections by Appling, Cahill, and Mathews and I cannot understand why they divide by the hydrogen concentration by $10^{-7}$. Why not just leave it ...
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Measure the concentration of lactose in dairy products [closed]

I would like to measure the concentration of lactose in various dairy products : milk, cheese, yoghourt... How is it done in labs ? How can I do that using cheap equipments ? Thanks