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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21 views

How to determine the concentration of the acid solution by titration? [closed]

A student determined the concentration of a hydrochloric acid solution by titration with $\pu{25.0 cm3}$ portions of a $\pu{0.05 M}$ primary standard solution of anhydrous sodium carbonate. The ...
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1answer
23 views

What formula allows adjusting balance of (Ethyl Alcohol / Water / Caffeine powder) to know concentration for the Caffeine solution?

I am experimenting with different levels of concentrated caffeine solution. The solution has a small percentage of ethyl alcohol, in the $\ce{H2O}$. Problems encountered too much ethyl alcohol ...
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1answer
30 views

Electrochemistry conditions for voltage to increase in a galvanic cell

I understand that increasing the concentration of reactants in a galvanic cell generally causes the voltage of the cell to increase. But is that really the case always? Consider a standard cell of ...
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17 views

Can isomers have different molar mass? [closed]

I was asked to research this question at school, but somehow none of the websites properly answer the question in yes or no.
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1answer
33 views

An exception to the IUPAC convention for italicisation (typography)

According to IUPAC, only physical quantities and variables must be italicised. Section 8 Use of Italic and Roman Fonts for Symbols in Scientific Text of ICTNS Guidelines for Drafting IUPAC Technical ...
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2answers
854 views

What is the difference between chemical equilibrium and dynamic equilibrium?

Is chemical equilibrium and dynamic equilibrium the same thing? Both point to the reversible reactions and no net changes in the concentrations of product and reactant. Dynamic equilibrium from ...
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1answer
57 views

Does the volume change when the reactions occur? [closed]

I have this reaction (all substances are gaseous): $$ \begin{align} \ce{A + 4.5 B &→ C + 2 D + 2 E}\tag{R1}\\ \ce{C + 7.5 B &→ 8 D + 2 E}\tag{R2} \end{align} $$ Does the volume change when ...
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1answer
51 views

How to dispose of NaOH solution? [closed]

I have a range of sodium hydroxide solutions with different concentrations. (from 1.0 mol dm^-3 to 0.5 mol dm^-3). The max volume of each is 100ml. How can you easily dispose of these? Can I pour them ...
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1answer
72 views

How to calculate the number of protons in a sphere given the volume and the pH?

The spherical radius of a nano-droplet of a solution ($\mathrm{pH}$ of which is $6$) is given as $\pu{20nm}$. I can find the molar concentration of $\ce{H+}$ and subsequently the number of $\ce{H+}$ ...
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1answer
40 views

Calculating the Ionic strength of sodium acetylsalicylate

With the addition of aqueous NaOH to an aspirin solutions in water the reaction will yield products of sodium acetylsalicylate and water. I would like to measure the amount of sodium apsirin formed ...
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Meaning of mass concentration “units” % m/v [closed]

In a saline solution that is 5.750% (m/v) potassium iodide $(\ce{KI}),$ there are: a) 5.750 mL $\ce{KI}$ per 100.0 mL $\ce{H2O}$ b) 575.0 mg $\ce{KI}$ per 10.00 mL of $\ce{KI}$ solution c) 5....
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Angels Share seems bogus

What is the explanation of barreled spirits (at 62.5% ethanol) that undergo changes in concentration of ethanol. Whereas the volume after aging is typically reduced, the proof varies between low 100 ...
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Shouldn't mineral NPK fertilizer ingredients add up to 100%?

I use a mineral based fertilizer in powder form which - according to the label - should not contain any fiber and is fully soluble in water (I dissolved 2 times the recommended dosage and found no ...
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2answers
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Ratio of Water to Isopropyl Alcohol? [closed]

I am looking for a very simple formula to calculate the ratio of water to 99% isopropyl alcohol that I need to prepare a solution with a density of 0.925 g/cm3. I am assuming there is one.
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1answer
42 views

Determining the hydrogen peroxide content in acetic acid [closed]

For a project I have to determine the peroxide content in some samples, for which we plan to use glacial acetic acid. Unfortunately, I don't know the peroxide content of my acetic acid and because we ...
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1answer
35 views

How to find osmolarity of a solution contatining salt and glucose?

What is the osmolarity of a solution that contains $4.00\%$ (m/v) $\ce{NaCl}$ $(M = \pu{58.44 g mol-1})$ and $3.00\%$ (m/v) glucose $(M = \pu{180.18 g mol-1})?$ I know you have to convert percentages ...
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2answers
64 views

Can the rate of reaction of a Voltaic/Galvanic cell be determined theoretically?

I am conducting a chemistry practical in which I measure the voltage of a Zn-Cu Voltaic cell over time. Assuming that the surface area of the electrodes are known, concentration of reactants are ...
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1answer
78 views

Calculation of VOCs concentration (ppm) in the headspace of a bottle

What is the right way to calculate the concentration of volatile compounds in the air in a closed container? Suppose we have a $\pu{50 mL}$ bottle with $\pu{25 mL}$ of $100\%$ ethanol $(\ce{EtOH})$ ...
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2answers
389 views

How to convert P2O5 concentration to H3PO4 concentration?

Why are some elements such as phosphorus reported as $\ce{P2O5}$ concentrations when the materials have no $\ce{P2O5}$ in them. I would like an explanation of how the conversion is done between real ...
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1answer
61 views

10 g of NaCl is dissolved in 250 g of water. The mass fraction and molality of the solution is

10 g of NaCl is dissolved in 250 g of water. The mass fraction and molality of the solution is For calculating mass fraction, simply divided $10/250$ to get $0.04$. My book says it’s wrong. Is mine ...
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1answer
56 views

Bracketing Standards and dilutions

You are running an ICP-MS (Inductively coupled plasma mass spectrometry), with bracketing standards of 10 ppm(mg/L) K+ and 100 ppm K+ and sample of 500 ppm, prepared 5 mL diluted to 100 mL. Shouldn’t ...
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1answer
45 views

Constant concentrations in solution

I'm a high school student considering the concentration of solutions, and whether the concentration is constant at the bottom or towards the surface. Even then, how would I know that the solution is ...
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Removing potash from water using poly-aluminum chloride

I have been conducting an experiment for a school project, (removing metals from water)I added 50 grams of sulphate of potash to 2 litres of water, then allowed it to dissolve for a 24hrs. On two ...
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1answer
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Numerical simulation and calculations of pH

a. Reaction of $\ce{CO2}$ addition in water is as follows: $\ce{CO2}$ + $\ce{H2O}$ $\ce{->}$ $\ce{H2CO3}$ b. Then, pH of $\ce{H2CO3}$ solution is increased to 12 by addition of 1M $\ce{NaOH}$. ...
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1answer
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Is the density of solute same as the density of solution? [closed]

This problem came up while solving some problems on mass percentage and mole concept. Essentially, our teacher said that the $w/w\%$ and the $v/v\%$ for a given solution will be the same, because in ...
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1answer
154 views

One mole of solute (NaCl) is dissolved in 1 litre water. The molarity of solution is [closed]

One mole of solute ($\ce{NaCl}$) is dissolved in $\pu{1 L}$ of water. The molarity of the solution is: A) $\pu{<1M}$ B) $\pu{>1M}$ C) $\pu{=1M}$ D) $\pu{=2M}$ My answer: It’...
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1answer
47 views

How would I find the molarity/concentration of a gas using pV = nRT?

The problem I'm working on is: At $\pu{1100 K}$ and a total pressure of $\pu{1 atm}$, $\ce{SO3}$ is $75.0\%$ dissociated. $$\ce{2SO3(g) <=> 2SO2(g) + O2(g)}$$ Assume $\pu{1.00 mol}$...
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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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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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1answer
57 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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1answer
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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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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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2answers
99 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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1answer
73 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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1answer
96 views

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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151 views

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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1answer
225 views

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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153 views

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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247 views

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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1answer
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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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106 views

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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373 views

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 ...
3
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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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1answer
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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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2answers
60 views

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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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 ...