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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What is the purpose of using molar conductivity and equivalent conductivity instead of just conductivity [closed]
I am studying about molar and equivalent conductivity, and I just can't understand why. What advantages does it have to complicate things. Is there any simple and direct reason why these are used?
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Concentration term PPM [duplicate]
What volume do we assume when the concentration is written as mass by volume ppm?
I mean when mass by volume percentage is say 20%, we can say that 20g solute is present in 100 ml solution.
So if it ...
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Determining whether precipitation will occur or not and finding the concentration of a specific ion in a solution
The Ksp value of AY2 = 9.148 x 10^-2. I am having problem with calculating the concentration of ions. And without the correct concentration I can't find the Qsp/Kip so I'm stuck without them I can't ...
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Determination of the chloride concentration by the modified Volhardt method
Would someone help me solve a task:
The concentration of chloride ions in aqueous solutions can be
determined by the Volhardt method. An excess of silver nitrate is
added to the sample containing the ...
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2
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1
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A silly doubt on the concept of volume percent and concentration
I am trying to solve the following elementary problem of volume percent, however, I am not quite sure where my mistake is:
Ethanol has a volume-by-volume concentration of 93.3%. Calculate the volume ...
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Best regression model for a sigmoidal pattern
Students submit the data for an acid–base titration to my app.
The abscissa axis corresponds to the volume.
Along the ordinate axis are the pH values.
The curve I’m looking for must work automatically ...
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Equilibrium Solubility of CO2 in Aqueous Solution and its Dependence on H3O+ Concentration
The equilibrium solubility of $\ce{CO2}$ in an aqueous solution is given by three chemical reactions:
$$
\begin{align}
\ce{CO2(g) &<=> CO2(aq)}\label{rxn:R1}\tag{R1}\\
\ce{CO2(aq) + H2O &...
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1
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Are all salts completely dissociated in solution when put in smaller amounts than their molar solubility?
From what I understand, the solubility is given in terms of molar solubility (or $\pu{K_{sp}}$), from which it can be easily calculated). Indeed, the saturation point represents the maximum amount of ...
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Is it a convention to divide rate of reaction by stoichiometric coefficient?
If we consider a reaction
$$ \ce{A + B -> 3 C} $$
The rate of reaction is given by
$$ R= -\dfrac{\Delta[A]}{\Delta t} = -\dfrac{\Delta[B]}{\Delta t} = \frac13\dfrac{\Delta[C]}{\Delta t} $$
I know ...
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Relationship of acids and bases with pH. (Proportional Relationship) [duplicate]
Can someone please clarify the relationship between acidic-basic strength and pH? I have come across conflicting information and am unsure about the correct understanding.
Some people including my ...
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Scrubbing methanol and ethanol from a gaseous mixture
I have a gaseous mixture (air) at a temperature of approximately 30 degrees Celsius in which the following gases are present:
Oxygen 0 - 25%
Carbon Dioxide 0 - 20%
Methanol 0 - 100 ppm?
Ethanol 0 - ...
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2
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How to prepare solution of liquid reagent of the given molar concentration?
I have a liquid reagent with molecular mass $M = \pu{294.08 g mol^-1}.$ I'd like to prepare $V = \pu{400 ml}$ of solution of that reagent with a concentration $c = \pu{100 mM}.$
Does it mean I have to ...
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Dilution formula for NH3 solution [closed]
I need this for an experiment:
ca. 3 mL concentrated (15 M) aqueous ammonia solution, NH3 (from a dropping bottle.)
I have the NH4OH pictured below. How can I dilute it to get what I need? What is the ...
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3
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Why do we have to prevent the hydrolysis of iron(III) nitrate?
I want to make particular concentration of ferric ions from $\ce{Fe(NO3)3.9H2O}$, and then I found this video
It says that we have to add nitric acid to prevent iron from hydrolysis, what does it mean?...
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Calculating concentration quotient and determining direction of reaction for equilibrium involving gases
I'm currently working on a chemistry problem involving chemical equilibrium, and I'm having some trouble figuring out how to calculate the concentration quotient $Q$ and determine the direction in ...
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How does an equilibrium move when increasing the concentration of water?
I have the following equilibrium given:
$$\ce{[Co(H2O)6]^2+(aq) + 4 Cl-(aq) <=> [CoCl4]^2-(aq) + 6 H2O(l)}$$
(I imagine the (l) for water is wrong, as the water is a part of the solution)
The $\...
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1
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Chemical species equations in a kinetic mechanism of combustion
In combustion, for a kinetic mechanism involving $m$ reactions and $n$ chemical species, of the form
\begin{align}
\begin{cases}
\nu_{11}' \mathcal{S}_1 + \nu_{12}' \mathcal{S}_2 + \dots + ...
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How are gravimetric analyses of particulate matter performed, in order to determine particulate matter concentration in air?
I've been surfing Google Scholar a bit and learned that a common and comparatively less expensive method of measuring particulate matter concentration in air was analysis through gravimetric methods. ...
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How to find the added volume $V_e$
We have a volume $V_A$ of a solution of $\ce{CH3COOH}$ acid, its molar concentration is $C_A$ and it has $pH_0=3,4$, we add a volume of $V_e$ from distilled water to it, in this case it has $pH_0'=3,7$...
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Does "brine rejection" happen for dissolved gases as well?
"Brine rejection" is the effect of sea ice pushing out dissolved salts, forming sweetwater ice and brine. I understand "freeze distillation", a method to concentrate alcohol in ...
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2
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Why is molality measured in terms of the solvent instead of the whole solution? [duplicate]
The molality $b$ of a solute dissolved in a solvent is given by:
$$b_\mathrm{solute} = \dfrac{n_\mathrm{solute}}{m_\mathrm{solvent}}$$
where $n_\mathrm{solute}$ is the amount of solute (e.g. in mol) ...
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What is the goopy substance that forms before CaCO3 precipitates?
I do a lab where we mix a solution of sodium carbonate with a solution of calcium nitrate. As expected, calcium carbonate (white solid) precipitates out. However, if the concentration is high enough, ...
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1
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Find the w/w percentage nitrogen in an ammonium nitrate solution
MCQ Question:
What is the w/w percentage of nitrogen (N) in an ammonium nitrate solution with a density of 1.05 g/cm3 and a molar concentration of 2.1 mol dm-3?
(a) 2.8 %
(b) 11.2 %
(c) 16.0 %
(d) 5.6 ...
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2
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Finding unknown concentration using HPLC standard curve
I calculated a standard curve equation from a given concentration and peak area, which gave me $y=1994.6x+218.4$. I made the graph with the $x$-axis μg/mL and $y$-axis peak area.
The question is, a ...
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1
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Calculate volume of hydrogen gas evolved
MCQ Question:
Ammonia borane in water can release hydrogen upon hydrolysis while forming NH4BO2 as the other
product.
The volume (cm3) of hydrogen gas which will be evolved from the hydrolysis of 309 ...
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2
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1
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77
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Finding concentration of ascorbic acid
Question:
A person applied following procedure for the determination of ascorbic acid (Vitamin C) in a sample solution.
A volume of 20.00 cm3 of the ascorbic acid sample was reacted with 25.00 cm3 of ...
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Even in an acidic solution with a pH equal to 0, there are only 1 mol/L H3O+ ions, while there are approx. 54 mol/L water molecules
I find this sentence in my high school chemistry book to be confusing:
"Even in an acidic solution with a pH equal to 0, there are only 1 mol/L H3O+ ions, while there are approx. 54 mol/L water ...
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Buffer solution of NaH2PO4 and Na2HPO4
We have this exercise without solutions
From a 0.2 M $\ce{NaH2PO4}$ solution and a 0.2 M $\ce{Na2HPO4}$ solution, a buffer
solution with pH = 6.8 is to be prepared. The total concentration of
$\ce{...
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Calculate the titer of a solution
I hope this is the right place to ask. We have this exercise without solution
One litre of diluted sodium hydroxide solution (c = 0.15mol/litre) is
to be prepared in the laboratory. The titer from ...
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What is the maximum number of silver(Ⅰ) ions in one litre of a 0.003 M sodium sulfide solution?
What is the maximum number of silver(Ⅰ) ions that can be present dissolved in one litre of a $\pu{0.003 M}$ $\ce{Na2S}$ solution?
According to my book, silver(I) reacts with sulfide producing $\ce{...
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1
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Why doesn't the volume of NH3 = 325 ml in this problem? [closed]
I'm struggling with the problem below, and don't understand why
A buffer solution with pH = 9.0 is to be prepared from a 0.2 M ammonia
solution and a 0.15 M $\ce{HCl}$ solution. The sum of the molar
...
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How to find the deprotonation percentage of an acid?
Given is an aqueous solution of mandelic acid (M = 152.2 g/mol; $pK_a$ = 3.4) with a molar concentration of 0.3 mol/ liter. A $\mathrm{pH}$ value of $2$ is measured for the aqueous mandelic acid ...
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Concentration of products in tank reactor
I want to calculate the concentrations of all components in the outlet stream of the reaction: C$_2$H$_6$ -> C$_2$H$_4$ + H$_2$ (A -> B + C)
I have a tank reactor (isothermic and isobar): V= $...
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How to calculate the pH value of a Carbonate solution?
I read the similar questions suggested when submitting my question but they didn't help me How can one calculate the pH of a solution? How to calculate pH of the Na2CO3 solution given ambiguous Ka ...
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1
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How much chlorine is there in 1 g of sodium dichloroisocyanurate? [closed]
According to Wikipedia, molar mass of anhydrous sodium dichloroisocyanurate is approximately 220 g per mole, and molar mass of Cl2 is 71 g per mole. Therefore there is 323 mg of chlorine in 1 g of ...
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Does concentrated HNO3 oxidize aluminium to form a protective oxide layer, or is the oxide layer already present so HNO3 is unable to react? [duplicate]
Sources on the internet like this one only say that aluminium does not react with concentrated or dilute $\ce{HNO3}$.
I have seen other related questions on this site but none answers my question ...
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Find the minimum concentration so that it doesn't precipitate
Calculate the solubility of silver chloride.
a) in pure water
b) Calculate the minimum concentration of ammonia that prevents precipitation in a solution that
contains $0.1$ mol of AgNO3 and $0.01$ ...
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What happens when you mix a salt with a strong base? [duplicate]
This doesn't come off from a question but it came to my mind. Take an example of $NH_4Cl$ as the salt and $NaOH$ as the strong base. What would happen to the pH for example? I'm guessing that the salt ...
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Determining the concentration of a very small sample of sulfuric acid
How can we determine the concentration of sulfuric acid in a very small sample?
We are working on a “mechanical” process that transports a very small amount of sulfuric acid to an instrument and we ...
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What is the correct method for converting a concentration given in ppm to molarity?
I need to convert a concentration of dissolved boric acid $(\ce{H_3BO_3})$ in water (at high temperature and pressure) from ppm to mol/L.
Concentration of boric acid: $c_{ppm}=1500\ \ce{ppm}$
Molar ...
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How does the partial pressure of oxygen relate to its concentration in water?
I've read that the partial pressure of oxygen in water will be the same as the partial pressure of oxygen in the atmosphere, but that the saturation of oxygen in water is dependent on factors like ...
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Is there any material that, subjected to electricity, extends in size in multiples without substantial change in heat for human use? [closed]
Is there any material that can molecularly restructure so as to expand its intra- or inter-molecular distance by no less than three-fold without substantially losing its structural integrity and ...
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What does "bulk concentration" mean?
In biogeochemistry/ecosystem models, the concentration of phytoplankton in sea water is often termed "bulk concentration" with units mol P/m^3 (moles of phosphorus per cubic meter, assuming ...
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Dependence of rate on the nature of reactants and other factors
Consider a reaction
$$\ce{aA + bB -> cC + dD}$$ whose reactants are given by A and B and the products are C and D.
The rate of this reaction is given by $$\frac{dx}{dt} = -\frac{d[\ce{A}]}{adt}= -\...
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Finding mole fraction from molarity and density
A solution of H2SO4 with concentration of 2,325 M at 15 °C has a density of 1,140 g/mL. Find the molar fraction.
I know what molar fraction is, but I really don't understand how to get it from the ...
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A method to create NH3-NH4Cl buffer solution using titration method
My aim is to create a basic buffer solution.
I know that to create a basic buffer solution, we need a strong acid and weak base. In my case I have chosen $\ce{NH3}$ and $\ce{NH4Cl}$.
Using titration, ...
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1
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197
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How does pressure affect the color of reaction medium with equimolar amounts or reactants and products at equilibrium?
Chlorine gas is pale yellow-green, and both hydrogen and hydrogen chloride are colorless gases. According to the Le Chatelier's principle, the change in pressure will not affect the following ...
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0
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530
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Molarity 1% ammonia solution?
I have a stock solution of 25% ammonia, with a density of 910 g/L. I used this to make a 1% ammonia solution by mixing 20 mL 25% ammonia into 480 mL distilled water with 5.84 g NaCl (0.2 M), density ~...
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How does adding oxalic acid to water change the volume of the solution?
Does $\pu{87.4 mL}$ of $\ce{H2O}$ and $\pu{12.6 g}$ of $\ce{HOOC-COOH.2H2O}$ create $\pu{100 mL}$ of a solution?
So in our practical class our teacher wanted to make $\pu{100 mL}$ $\pu{1 M}$ aqueous ...
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1
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PFR reactor: -1/r vs conversion plot
A generic reagent A is considered. The behavior equations of a CSTR reactor is the following:
$$
\tau = c_\mathrm{A,0} \intop_0^{X_\mathrm{A,final}}
\dfrac{1}{-r_\mathrm{A}} dX_\mathrm{A}
$$
where $\...
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