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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119 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
47 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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1answer
3k views

How many moles NH4Cl must be added to NH3 to create buffer with pH=9?

How many moles of $\ce{NH4Cl}$ must be added to $\pu{2.0 L}$ of $\pu{0.10 M}$ $\ce{NH3}$ to form a buffer with $\mathrm{pH}=9$? Assume the addition does not change the volume of the solution ...
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0answers
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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
54 views

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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ionic equlibrium [closed]

question is related to ionic euilibrium please answer option Q as soon as possible
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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
118 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
2k views

How to calculate the amount of substance of sodium that are in 10 mL of 30% sodium chloride?

How much of sodium is there in 10 mL of 30% sodium chloride? $30\%$ of $\ce{10 ml}$ is $\pu{3 g}$ $\ce{NaCl}$. There is $\pu{3000 mg}$ of $\ce{NaCl}$ and would that be divided by the molecular weight ...
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1answer
71 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
68 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
32 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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How to increase the density of mercury 13.59gram(1ml) to 17gram(1ml) or more? [duplicate]

How to increase the weight of mercury 13.59gram(1ml) to 17gram(1ml)? and still in a liquid form. And it should not be expensive. please explain the process. I have the sample with me(500ml weighing 8....
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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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53 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
68 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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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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Why is active mass of a pure solid or liquid always taken as unity?

Active mass is defined as the molar concentration ie. number of Gram-moles per litre. My book then wrote Active mass of pure solid/liquid is always 1 . The book reasoned that Molar ...
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2answers
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How to calculate the total concentration after mixing two solutions of differing dilutions?

If you mix $\pu{20 ml}$ of $\pu{3 M}$ sugar solution with $\pu{30 ml}$ of a $\pu{5 M}$ sugar solution, what solution do you end up with? What I did, \begin{align} \text{volume} &= \frac{\text{...
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1answer
390 views

Finding the concentration of hydrochloric acid by titration

In a class experiment, $\pu{20 mL}$ of hydrochloric acid was diluted with distilled water to $\pu{500 mL}$. $\pu{20 mL}$ of this diluted solution was added to $\pu{20 mL}$ of $\pu{0.1 M}$ sodium ...
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2answers
138 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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1answer
51 views

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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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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3answers
7k views

How to increase the concentration of HCl

Today I have purchased some $\ce{HCl(aq)}$ on my local market with a concentration of 23%. However, I need to obtain a concentration of 37% in order to perform an experiment. Can I use distillation ...
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3answers
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How to calculate the molarity of a gas?

If I have $X$ moles of a gas and I put them in a container at constant volume $V$, will the molarity of the gas then be $X/V$?
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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
36 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
64 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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27 views

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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2answers
11k views

What is an equivalent?

I want to know what is an equivalent and how is it different from equivalent mass. How to calculate and why is it used in chemistry for knowing concentration?
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1answer
4k views

How to calculate the concentration based on dilution of a stock solution?

One of my exam questions is about lipstick and calculating the amount of lithium in the lipstick by AAS. The determination took place by making standard solutions with known concentrations of lithium. ...
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2answers
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Calculating the molarity of DNA in a cell

In the following questions use a value of 3 for $\pi$, $6 \times 10^{23}$ for Avogadro’s number and $660$ for the molecular weight of $\pu{1 bp}$ of DNA. The volume of a sphere of radius $r$ is $4/3\,...
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58 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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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
27 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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2answers
36k views

How to convert g/L to mol/L

I know I should divide $\pu{g L-1}$ by the molar mass of the substance, but I don't seem to find the specific answer on Google. So just to be sure: If I have $10^{-5}~\pu{g L-1}~\ce{Cu^2+}$ solution, ...
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3answers
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Finding is the concentration of H⁺ in a benzoate buffer solution after adding HCl

Q: A buffer with a $\mathrm{pH}$ of 4.44 contains $\pu{0.21 M}$ of sodium benzoate and $\pu{0.12 M}$ of benzoic acid. What is the concentration of $\ce{[H+]}$ in the solution after the addition of $\...
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2answers
1k views

Plotting a calibration curve for Gas-Liquid Chromatography

Question: The given graph of abundance of different samples of butanol with respect to time is- Textbook solution: But why aren't the points like this: $(20,5);(40,10);(60,15);(a,7)$ after which, ...
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51 views

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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72 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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1answer
2k views

Concentration of hypochlorous acid and hypochlorite

Given a total chlorine concentration $c(\ce{Cl})_\text{tot}= \pu{0.1 M}$, with $\mathrm{pH}(\ce{Cl}) = 8$ and $\mathrm{p}K_\mathrm{a}(\ce{HOCl}) = 7.5$, how would you find the concentration of $\ce{...
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2answers
100 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
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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1answer
123 views

How to approximate the pH of a box of water molecules with one proton?

I have a cubic box of length $L = 12.42\ \mathrm{\overset{\circ}A}$, containing $60\ \ce{H2O}$ molecules and $1\ \ce{H+}$ ion. How can I approximate the $\mathrm{pH}$ of the system? Following the ...
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1answer
4k views

Acetic Acid % in vinegar? Given average molarity of acetic acid

Question: The stockroom claims the percent acetic acid in vinegar to be $2.0\%$. The density of vinegar is $\pu{1.106 g {mL}-1}$. Using average molarity given ($\pu{0.2844M}$) calculate the mass ...
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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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2answers
5k views

Molar Absorptivity of Copper(II) Sulfate

What is the molar absorptivity of copper sulfate? I am trying to find the molarity of copper sulfate solution by absorption in a spectrophotometer with a cuvette. However, I can't find $\varepsilon$, ...
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1answer
11k views

How to determine the iron content in spinach with a spectrometer?

I used a spectrometer to find the absorbency of 5 solutions with different iron concentrations. \begin{array}{rrrrr} \ce{Fe (III)} / \pu{mol L-1} & \text{Absorbance} & V(\ce{HCl}) &...
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14 views

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
164 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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