# 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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### 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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### 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 ...
35k views

### How do I calculate the concentration of sulphuric acid by a titration experiment with sodium hydroxide?

In my latest chem lab the objective was to create a primary standard of $\ce{NaOH}$ and use it to determine the concentration of sulfuric acid. The first part of the lab was determine the molarity of ...
21 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 ...
618 views

### Can water volume reduce with introduction of another chemical [duplicate]

Can a chemical be introduced to a volume of water which can actually reduce the volume of water in that container?
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 ...
2k views

### How can a substance be diluted to nothing?

If I start with a small amount of a substance, and I dilute that substance with billions of gallons of water, what is the scientific explanation for there being no (actually zero) remaining molecules ...
13k views

### Effect of evaporation on the concentration of a saturated solution

When evaporating a saturated solution, does the concentration remain the same? My thinking is that because the solution is saturated, and the volume is decreased, the excess solute would precipitate ...
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.
6k 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 ...
4k views

### Does the concentration affect the voltage in electrochemistry?

For my electrochemistry lab I'm using $\pu{10 mL}$ of $\ce{ZnSO4}$ and $\pu{10 mL}$ of $\ce{CuSO4}$ solutions connected with a salt bridge. I connect $\ce{Zn}$ metal and $\ce{Cu}$ metal to a voltmeter ...
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 ...
2k views

### Relationship between pH and volume

I had prepared two different volume of solution: $\pu{500 mL}$ and $\pu{100 mL}$ with same concentration ($1\%$), but I obtain different $\mathrm{pH}$. Will volume affect $\mathrm{pH}$?
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 ...
536 views

### What was the lithium concentration in 1940's 7-Up?

I just came across this article in the New York Times, where lithium (or more correctly, lithium salts), a known anti-depressant had been added to beverages in the 1940's. They also mention that a ...
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 ...
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 ...
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 $\ce{H+}$ ...
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 ...
69 views

### 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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### 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 ...
35 views

### 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 ...
183 views

### How to find the ionization constant of an unknown weak acid?

A $\pu{0.45 M}$ solution of a weak acid, $\ce{HX}$, has a $\pu{pH}$ of $4.5$. What is the ionization constant, $K_a$, of the acid? $\ce{[HX]}$ is already given as $\pu{0.45 M}$. $\ce{[H+]}$ is given ...
53 views

### 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.
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. ...
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 ...
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 ...
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 ...
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 ...
4k 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 $\varepsilon$, ...
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 $(\ce{EtOH})$ ...