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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30 views

Deposition of saturated solution and affect of evaporated water

20g of water is evaporated from 200g of saturated solution of KNO3(aq) at 60°C by heating and the solution was cooled to 20°C. How many grams of KNO3 were deposited? The solubility of KNO3 in 100g of ...
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2answers
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Effect of water vaporation on saturated solution

At a high temperature, water is evaporated from the saturated solution by heating. What is the solution losing exactly by the fact that the water left the saturated solution? Does it affect its ...
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2answers
59 views

When calculating the distance between molecules in a solution, is it reasonable to approximate a sphere around each molecule?

I am attempting to calculate the average distance between molecules in a particular concentration of a solution. My first instinct was to treat the solution as a system of spheres surrounding the ...
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Deciding whether a precipitate would be soluble in water or not by calculation (problem solving)

This question is purely mathematical, I just could not understand how to approach it. (For reference the question mentions that compounds with solubility higher than 1 mol/L are soluble and insoluble ...
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19 views

Calculating stock solutions

In the question it mentions that the protein forms dimers. Does that affect the RFM of the protein when I use it in my calculations (10kDa). For example for part a, would it just be. 0.01/10, 000 = 1 ...
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1answer
33 views

A question about ligand binding

I have done part a and part b but I keep getting a negative concentration for part c. For part a I got $\pu{2 \mu M}$ For part b I got $\pu{5.051 \mu M}$ For part c, I get $2=3.2 + \text{[bound ...
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1answer
34 views

Resulting ions concentration after mixing solutions

$\pu{1 g}$ of $\ce{NaHCO3}$ and $\pu{2 g}$ of $\ce{Na2CO3}$ were dissolved in $\pu{50 mL}$ of water known as solution A. Solution A was mixed with $\pu{450 mL}$ of $\pu{0.154 M}$ of $\ce{NaCl (aq)}$ ...
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1answer
48 views

What does the equilibrium constant mean for reactions with very small concentrations?

When you calculate the equilibrium constant for a reaction with a higher concentration of reactants, the answer is fairly intuitive. For example, for the reaction: $$\ce{A + B <=> C}$$ Where we ...
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Using the method of differential absorption to determine the ethanol content of an unknown sample [closed]

I have completed a whole set of FITR-ATR spectra analysing 6 solutions of ethanol-water mixtures, all at different concentrations of each. I have now been instructed to use the method of differential ...
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32 views

Acorrect range of concentrations for the reactants in the equilibrium reaction

What would be a correct range of concentrations for the reactants in the equilibrium reaction, $\ce{Fe^3+(aq) + SCN-(aq) <=> FeSCN^2+}$? For a Chemistry project I am measuring the effects of ...
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1answer
56 views

Preparing aqueous solution of ethanol [closed]

You need to prepare $\pu{250.0 mL}$ of an aqueous solution of ethanol in the concentration will be $\pu{0.500 mol L-1}$. You have $\pu{100 mL}$ of a commercial solution of ethanol in water $(35.0\% \,...
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1answer
129 views

Plotting the data using Beer-Lambert law [closed]

For the spectroscopy lab we had a stock dye ($\pu{1.00E-4 M}$ Erioglaucine Blue) that we had to dilute. We had to dilute $\pu{1 mL},$ $\pu{3 mL},$ $\pu{5 mL},$ $\pu{8 mL},$ and $\pu{10 mL}$ in $\pu{...
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1answer
57 views

Finding concentration of hydronium ions in water after adding hydrogen chloride gas [closed]

A sample of hydrogen chloride gas, $\ce{HCl}$, occupies $\pu{0.932 l}$ at a pressure $\pu{1.44 bar}$ and at a temperature of $\pu{50^\circ C}$. The sample is dissolved in $\pu{1 l}$ of water. What is ...
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Performing a Redox Titration on a Vitamin C Sample Solution Containing Cellulase enzymes

I was wanting to performing an Iodometric Redox Titration on a Vitamin C sample solution created from allowing diced citrus fruits to sit in a water + cellulase solution. Because vitamin c is water ...
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2answers
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Is is valid to compare reaction quotient to $K_p$ as well as $K_c$?

Can I use the reaction quotient compared to $K_p$ to answer the following question? The solid $\ce{XY}$ decomposes into gaseous $\ce{X}$ and $\ce{Y}$: $\ce{XY(s) <=> X(g) + Y(g)}$ with a $K_p = ...
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Kinetics of Decomposition of Hydrogen Peroxide [duplicate]

Consider the decomposition of Hydrogen Peroxide: $$\ce{H2O2 -> H2O + 1/2O2}$$ The rate law for this reaction is : $$\text{Rate} = k[\ce{H2O2}]$$ Further $$\text{Rate} = -\frac{\mathrm d[\ce{H2O2}]}...
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1answer
120 views

What is the size in m³ of a toxic benzene cloud when if 20.000 kg liquid benzene would vaporize?

Benzene is carcinogen, The short term exposure limit for airborne benzene is 5 ppm for 15 minutes see https://en.wikipedia.org/wiki/Benzene#Benzene_exposure_limits I would like to know which volume of ...
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1answer
78 views

Density of a sodium hydroxide solution

The specific gravity of a $50\%$ aqueous solution $\ce{NaOH}$ is $\pu{1.5298 g cm-3}.$ To my understanding, the $50\%$ means $50$ mass fraction $w,$ i.e. $\pu{500 g}$ $\ce{NaOH}$ in $\pu{500 g}$ $\ce{...
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1answer
74 views

Calculating the concentration of product in a solution based on the peak area of HPLC [closed]

Please help me resolving the following: A sample solution, $\pu{0.24mg/mL}$ Compound A, is exposed to heat to form Compound B. From HPLC data report I have peak area for Compound A and Compound B. ...
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1answer
40 views

How does the surface tension of water decrease with an increase in the concentration of NaCl?

Can anyone help me with the theory of surface tension? My chemistry experiment is related to the surface tension and concentration of NaCl. I am confused about my hypothesis. On the internet, I found ...
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1answer
55 views

Concentration and Half Life of reactants A and B

Since reaction is first order with respect to both reactant A and B, I can write, $$ k=\frac{1}{t} \ln{\frac{a}{a-x}} $$ where a is initial concentration of reactant and a-x is remaining ...
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1answer
69 views

Find volume of ammonia gas required to prepare a solution of given pH [closed]

Calculate the volume of gaseous ammonia $(K_\mathrm{b} = \pu{1.8E-5})$ to dissolve (at NTP) in $\pu{100 mL}$ of water in order to obtain a solution with $\mathrm{pH} = 11.0.$ Consider volume variation ...
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1answer
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Detecting carbon dioxide concentration using mosquito neurons

At the Mauna Loa Observatory the concentration of atmospheric carbon dioxide is measured using the absorption of infra-red light. This is a statistical technique that requires constant careful ...
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5answers
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Is it possible to achieve a level of “truly zero” concentration? [duplicate]

If we take some aqueous solution and dilute it further and further, will the concentration of the solution ever get to zero? I would say no, simply because total dilution implies that all the ...
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2answers
144 views

Determination of percentage of Methanol in an Alcohol based hand sanitiser [closed]

Note: I am looking for advice on a chemical test - not a sermon. I expect that this is entirely on topic in this forum, downvotes and sermon comment notwithstanding. More than about 5% of Methanol in ...
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2answers
102 views

Calculating the amount of oxygen in a glass using candle burning time

I would like to calculate the amount of oxygen or concentration of oxygen in a glass or conical flask using candle burning time. I am thinking of a simple way to calculate this based on the fact that ...
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1answer
38 views

Dependency of concentration terms on temperature [closed]

I wanted to know why molarity is temperature-dependent whereas molality is temperature-independent.
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1answer
37 views

An equilibrium question involving mixing equal volumes of HCl and H2SO4

Question: Calculate the concentrations of H3O(+) and SO4(2-) in a solution prepared by mixing equal volumes of 0.2M HCl and 0.6M H2SO4. (Ka1 for H2SO4 is very large, and Ka2 for H2SO4 is 1.2E-2) Here ...
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1answer
68 views

Calculate molarity given density and mass percentage [closed]

Problem Calculate molarity of a solution of $\ce{H2SO4}$ with density $\pu{1.198 g/cm3}$ and containing $27~\%$ mass of $\ce{H2SO4}.$ Answer My approach I converted the density to g/l. Then i took ...
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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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1answer
29 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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61 views

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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1answer
53 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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2answers
103 views

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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1answer
43 views

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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1answer
23 views

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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1answer
166 views

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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57 views

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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1answer
34 views

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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1answer
59 views

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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1answer
106 views

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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2answers
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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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1answer
63 views

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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39 views

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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3answers
129 views

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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0answers
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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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