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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How can a voltage reading be converted into concentration of a solution? [closed]

I'm trying to construct an Arduino device that measures the concentration of salt ions in a saltwater solution. I've figured out how to take a reading of the voltage, but how can I (mathematically) ...
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pH and concentration problem I don’t understand [closed]

Novocaine, C13H21O2N2CI, is the salt of the base procaine and HCI. The ionisation constant is 7x10^-6. Is a solution of novocaine acidic or basic? Furthermore, what are the concentrations of H3O+ OH- ...
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HCl labeled 31.45% concentration (20° Baume) [closed]

Just bought a standard concentration of HCl solution. The 31.45% is weight-by-weight & not weight-by-volume, correct?
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How would I find what specific wavelength I need to measure for a specific chemical in spectrophotometry (calcium perchlorate)?

I am currently doing a research project, and for it, I would like to use a photospectrometer to find the concentration of Calcium Perchlorate in my sample solutions. My current method of data ...
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51 views

Is the wavelength of light generated through a chemical reaction independent?

The chemical reaction in question is the reaction between Luminol and hydrogen peroxide. Is the wavelength of light generated through this reaction dependent on the concentration of either reactant? I ...
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172 views

Why does mercury(II) nitrate form only when using concentrated nitric acid?

In the reaction between mercury and nitric acid, mercury(II) nitrate only forms when concentrated nitric acid is heated up and added to it, if the acid is dilute, mercury(I) nitrate forms. I ...
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22 views

Osmolality and osmolarity of infant formula

Actually, this question is about the following sentence, which I have seen (in various forms) in numerous papers (e.g. this one and this one): The American Academy of Pediatrics advises that formulas ...
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39 views

Calculate concentration of product after time passed

If I have two parallel reactions: A --> P$1$ (k$_1$ = $0.00010$ s$^{-1}$) A --> P$2$ (k$_2$ = $0.00050$ s$^{-1}$) and know that the initial concentration of A is $0.0417$ M. How can I ...
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Calculating the concentration of reactants and products in parallel reactions after a time t

A substance A reacts with a solvent B to form an intermediate product IP. The reaction is bimolecular. The conc. of the solvent is constant at $12$M. IP can then react to form the two products P$1$ ...
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Determining reaction order from absorbance

A reaction is initiated in a solution which contained a dissolved component. The transmittance was measured at $\pu{240 nm}$ in a $\pu{2.54 cm}$ long cell. At $t = 0$ the transmittance was $1$. $\...
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Could Nernst Equation fail at high Ion concentration diffrence

When I was learning about neuroscience, I came across the Nernst equation and found out that it is only dependent on the quotient of the ion concentration outside compared to the inside. So, now I ...
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Why we are dividing rate of reaction with respect to a species by its stoichiometry coefficient to find rate of that particular reaction

If there is a reaction like this $$\ce{ H2 + Cl2 -> 2HCl}$$ I can understand that each individual species (reactant or product) can have different rates and we can compare them like this, $$-\frac{...
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How much solvent do you add for a 1:20 dilution, and why is it called 1 to 20? [closed]

A 1:20 dilution implies that you take 1 part of stock solution and add 19 parts of water to get a total volume of diluted solution equal to 20 times that of the stock solution So is ...
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Plotting second order reaction with different reactants

In a laser flash photolysis experiment, $\ce{C6H5NH2}$ $(C_0 = \pu{60 \mu M})$ is oxidize to its corresponding radical cations. There are three possible reaction pathways for the formation of the ...
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Is this true for conductivity of mixture of two solutions equal to the sum of conductivities of each solution?

Suppose $\ce{Na2SO4}$ has a conductivity $\pu{2.6 \times 10^{-4} S cm-1}$ and on mixing $\ce{CaSO4}$ to saturation, the conductivity becomes $\pu{7.0 \times 10^{-4} S cm-1}$. So, Is the conductivity ...
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Quantifying soapiness; there's pH, pKa and pO2, is there a p_soap or p_surfactance?

Yes, $\mathrm{pH}$ is a concentration, $\mathrm{p}K_\mathrm{a}$ is a dissociation constant, and $\mathrm{pO_2}$ is a partial pressure. These are (roughly speaking) ways to indicate how much of a key ...
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Calculating the weight of a chemical within a liquid mixture

I want to know the weight of ethylene glycol in a mixture of Shellzone 50/50 Antifreeze. I have taken the mid-range of 40-60% from the safety data sheet(SDS) for the amount of ethylene glycol in the ...
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Translating from milligrams in the pill to Ki at the receptor

Many places (e.g. Wikipedia) report the action of a drug on the various receptors, transporters, ion channels, and the like in terms of the Ki(nM). (This is for drugs that act primarily through such ...
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Why is the concentration of gases denoted in form of partial pressure? [duplicate]

In most of the chemical laws of chemistry involving concentration of products or reactants like equilibrium constant, reaction quotient, Henry's law, Nernst equation etc, I often see a similar note ...
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Hydrogen concentration measurement without gas chromatography

Please suggest ways to measure $\ce{H2}$ concentration in a sample of gas containing $\ce{HCl},$ $\ce{CH4},$ $\ce{N2},$ $\ce{CO2}$ and trace amounts of chlorosilanes without GC. The problem is that I ...
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Calculating molarity of iodine solution after reaction

I made an iodine solution referring to the methodology provided in this link: https://www.thoughtco.com/vitamin-c-determination-by-iodine-titration-606322 $$\ce{KIO3 + 5KI + 3H2SO4->3I2 + 3H2O + ...
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A physical meaning of the Danckwerts boundary condition in terms of concentration profile (adsorption)

Can someone please explain to me in a simplified way, what exactly does a well-recognized Danckwerts boundary condition do to the concentration profile of adsorption phenomena? I just cannot find a ...
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The effect of increasing concentration of a cathode solution on the voltage in a galvanic cell

I am having trouble understanding a concept. In a galvanic cell, where electrolyte A is zinc (in a solution of zinc nitrate) and electrolyte B is copper (in a solution of copper (II) nitrate), why ...
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79 views

Effect of addition of inert gas on concentration in an equilibrium [duplicate]

We have the following equilibrium established in a container with movable piston at atmospheric pressure. $$\ce{N_2 (g) + 3 H2 (g) ⇌ 2NH_3 (g)}$$ Now how does the concentration of the reacting species ...
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Rate of a reaction when volume of the system varies with time

Background I was solving this question from this book and I was not able to get any of the options. The gaseous reaction $\ce{n_1 A_{(g)} -> n_2 B_{(g)}}$ is first order with respect to ‘A’. The ...
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485 views

Relationship between molar mass and density in solids

In ideal gases, it's pretty clear that 1 mole of gas occupies 22.4 L at STP. By knowing this, it's easy to calculate density given molar mass. However, this isn't true for solids. If I know molar mass ...
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Calculating the ionic strength for an aqueous solution containing potassium ferricyanide and sodium sulfate

I have the $100$ microM of K$_3$Fe(CN)$_6$ is dissolved in water and the following data: $$\begin{array}{c|c} \text{Experiment} & \ce{[Na_2SO_4]}/\pu{M} \\ \hline \mathrm{A} & 0 \\ \mathrm{B} ...
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will splitting a solution will keep the concentration values (and moles) the same? [closed]

I have this exercise from my H.W: and I am asked: if we split the solution into 3 different containers equally - how many moles will the solution have in each container? will the Cl- concentration ...
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Discrepancy when calulating mol weights with ChemSketch and Python RDKit

I am an IT guy with little knowledge of Chemistry, so please bear with me... For context: I am working with a system that has a lot of structures, their .mol files ...
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410 views

Finding mass percent through molality of potassium nitrate solution

Question An aqueous $\ce{KNO3}$ solution has a molality of $\pu{4.16 m}$ and a density of $\pu{1.08 g/mL}$. Calculate the percentage by mass $\ce{KNO3}$ of the solution. My Approach I know that ...
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1answer
232 views

The effect of dilution on the rate of a system in equilibrium

I'm attempting to answer a question from my textbook, however the answer that the textbook provides doesn't make sense to me. The question: Laura, a VCE chemistry student, loves graphs and wanted to ...
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347 views

Is the rate of a zero order reaction always independent of the concentration of its reactants?

Consider the following reaction : $\ce{A + B}$ $\rightarrow$ $\ce{Products}$ where order of the reaction w.r.t. $\ce{A}$ is $-1$ and order of the reaction w.r.t. $\ce{B}$ is $+1$. So, overall order of ...
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Total concentration conversion

when dealing with waste water and the total values of P, N, C are given in ppm units, what molecular weight is used for converting from ppm to molar? for Example- what will be 12 ppm of P(T) in Molar ...
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1answer
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More ions form pairs when concentration of acid increases, does that decrease the speed of reaction?

Electrical conductivity decreases as an acid becomes more concentrated because more ions form pairs. However, does that affect the speed of reaction of the acid as there is a smaller concentration of ...
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61 views

Finding the concentration from a dilution

This must be a very basic question but I have gotten confused over it. How would I find the concentration of each component of the reaction for each experiment from this data? I am guessing it can’t ...
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50 views

Calculate concentrations of ions after acid-base reaction given volumes and concentrations

A $\pu{35.0 mL}$ of $\pu{4000 ppm}$ $\ce{HCl}$ solution is mixed with $\pu{45.0 mL}$ of $\pu{0.1025M}$ $\ce{NaOH}$ solution. Assume volumes are additive. $$\ce{NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(...
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Physical Chemistry: Specifically the Dissolution of Carbonates

Please note this question is different to the other that keeps being mentioned. That one is about the concentration of just $\ce{HCO3-}$ when no $\ce {pH}$ was given. Whereas, in this one I am trying ...
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Do you need concentrated sulfuric acid to make Dische diphenylamine reagent and test for DNA?

I'd like to do a DNA quantification experiment for a college project. I don't want to use 16 M sulfuric acid. Is it possible to use more dilute acid and get a reasonably good result?
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Purify 65% nitric acid to 98% (WFNA)

What is the simplest way to purify 65% nitric acid (HNO3) to white fuming nitric acid (WFNA which is 98% pure)? Is it dehydration with concentrated sulfuric acid (H2SO4)? Is distillation needed to be ...
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119 views

Finding reaction rate constant for second order equation in Wolfram Mathematica [closed]

I’m working in Mathematica for my master’s project and I can’t work out how to find $k$ in the second order rate equations where I have a concentration vs time graph for $\ce{AHA}:$ $$\mathrm{rate} = ...
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Adding aluminum sulfate to neutralize an aqueous solution of sodium silicate with pH of 12.6

How much aluminum sulfate do I need to add to an aqueous solution of sodium silicate to neutralize the solution (pH from 12.6 to 7)? For a water treatment school project, we remove sodium silicate ...
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200 views

Enthalpy of dissolution of NaOH in small amount of water

is there a way to calculate enthalpy of dissolution of NaOH in small amount of water? I know that enthalpy of dissolution of sodium hydroxide in water is –44,5 kJ/mol. However it assumes the orders of ...
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How to calculate molar concentration from equilibrium equations with no initial concentration given?

I have the equations: \begin{align} \ce{CO2(g) + H2O(l) &<=> H2CO3(aq)} &\quad K_1 &= 10^{-1.47} \tag{1}\\ \ce{H2CO3(aq) &<=> H+(aq) + HCO3-(aq)} &\quad K_2 &= 10^{-...
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How to identify the concentration of nitric acid?

I have quite a small quantity of concentrated nitric acid I had acquired about two years ago. This was given to me by a friend in a couple of Pyrex volumetric flasks with stopper and some in a ...
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Electorchemical Systems (Newman 3rd edition) problem solving

I am trying to solve the very first problem (Problem 1.1) of Newman 3rd edition book. The book problem goes as follows: 'Starting with the following equation for the concentration overpotential: $\...
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Why would sodium ions want to go down just because of one side is more positive than the other? [closed]

From Khan Academy starting from 1:25, the narrator, while talking about the Electrochemical gradients, said that sodium ions would naturally want to diffuse down when having a high concentration up ...
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2answers
239 views

Does increasing one of the electrolytes in a galvanic cell increase the voltage?

I would like to know how you could increase the voltage in zinc and copper galvanic cell: $$\ce{Zn(s) + Cu^2+ → Zn^2+ + Cu(s)}$$ I know that temperature and surface area is a factor that affects the ...
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Calculate the percentage in a solution

The aim of this exercise is to determine the percentage (degree) of acetic acid in vinegar. For this purpose 10 mL of vinegar requires 8mL of sodium hydroxide of molar concentration 0.1mol/L to react ...
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Why is the concentration of hydrogen peroxide given as a percentage? For example, 3%, 6% [closed]

Conventionally, the concentration of solutions is given in moldm⁻³ or M, however, I am curious why the concentration of hydrogen peroxide isn't written in the same way.
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69 views

Calculation of concentration at equilibrium for extraction

The equation for equilibrium of solvent-solvent extraction is: $$\ce{PhOH(toluene) <=> PhOH (aq)}$$ An aqueous solution contain $\pu{1.5 \times 10^{-2} M}$ phenol and is shaken with the same ...

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