# 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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### Oleum concentration description

What is the meaning of "free" $\ce{SO3}$ and "combined" $\ce{SO3}$ in the oleum sample concentration description? Also what are these maximum and minimum values of % labelling in oleum sample?
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### Does simmering sparkling water change/decrease its mineral composition significantly?

I know that heating sparkling water will cause it to lose $\ce{CO2}$. Does this have any other effects on the water that remains, such as reducing its mineral content? I understand when non-...
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### How to determine concentration limits of a buffer that's limited by solubility?

I need to maintain a certain range of % of ionisation from a buffer. For e.g. Histidine buffer. When making high concentration of this buffer at (say) pH 7.2, 25'C, [concentration] is limited to 75mM ...
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### Concentration of acid when titration has reached equivalence point? [duplicate]

I'm currently working with a lab report concerning titration. One of the tasks is to calculate the concentration of the weak acid ($\ce{HOAc}$) and the strong acid ($\ce{HCl}$) at the equivalence ...
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### why do solids and pure liquids have no effect on yield and equilibrium? [duplicate]

There are three parts to my question. Part one: Let's assume we have a reversible reaction at equilibrium as follows : Calcium carbonate (solid) goes into calcium oxide(solid) and carbon dioxide(...
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### Calculating concentration of H+ Ions using Ka Value [closed]

I have this homework question that I am a bit stuck on for an answer. If anyone could help that would be great. Question: For a $\pu{0.2M}$ $\ce{HNO2}$ solution ($\pu{K_a= 4.5 \times 10^{-4}}$) ...
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### How to convert ppm to g/m3?

I'm not very comfortable with chemistry and I need to convert $\ce{CH4}$ concentration values in $\pu{ppm}$ to $\pu{g/m3}$. Is that possible? I've already researched a bit and realised that for water ...
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### How do molecules know how to behave when a disturbance occurs in an equilibrium?

I am well aware of Le Chatelier's principle, but what causes molecules to behave in such a way, my guess is that it all has to do with rates of reactions and frequency of collisions. When at a ...
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### Volume change of solute addition to solvent

When making and manipulating high concentration stock solutions of sugar excipients, is there a way to predict the corresponding volume effect that occurs? I am asking in order to be able to create ...
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### How do I measure out these salts using the proper method?

I'm planning on preparing a water solution using the following salts of reagent grade with approximately these concentrations: \begin{array}{lr} \ce{CaCl2} & \pu{10 mg/L}\\ \ce{Na2SO4} & \...
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### What does “percentage by mass” mean in the context of a compound dissolved in a solution?

Copper can be recovered from low-grade ores by 'leaching' the ore with dilute $\ce{H2SO4}$, which converts the copper compounds in the ore into $\ce{CuSO4(aq)}$. In a $\pu{50 cm^3}$ leach solution, ...
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### Lugol's iodine 5 % aqueous solution

There is Lugol's 5 % solution with 5 g of pure iodine and 7.5 g of potassium iodide. In one ml there should be 12.5 mg of iodine in sum. But there are suggestions telling that two drops of this ...
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### How to create a 3 M solution of ammonia from 25% ammonia

We have ammonia $25\%$. We also know $\rho_{\text{ammonia}} = \pu{0.86 \frac{g}{cm^3}}$, $\pu{25 ^\circ C}$. We want to produce $\pu{3 M}$, $\pu{0.5dm^3}$ ammonia. This means that there are some ...
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### How do you calculate the heat of a reaction given a table of heat of formation values?

So I've been trying to answer this question, and as far as I've learned it's $\Delta H^0_{\mathrm f}$(products)-$\Delta H^0_{\mathrm f}$(reactants), multiplying each by number of moles and such. ...
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### Finding the concentration of ferrous thiocyanate in calibration solutions

Concentration of $\ce{Fe(SCN)^{2+}}$ in calibration solutions Recall that the concentration of $\ce{Fe(SCN)^{2+}}$ in the calibration solutions is essentially the concentration of the $\ce{SCN-}$ ...
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### how to calculate mols Ag from AgNO3 solution

Sorry for the very basic question but its been a very long time since I've taken chemistry and I'm having difficulty solving this problem. If I titrate something with 1 molar AgNO3, adding 50 ml of ...
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### Will the reaction shift left or right?

The picture shows the correct answer. At Eq., I have: 3 Mol of A 1 Mol of B 12 Mol of C I was looking at each answer in terms of ratio of reactants to products, but its clearly not correct since I ...
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### How to calculate concentration of unknown saturated stock solution from diluted solution whose concentration is known?

I want to measure the solubility of a compound. I prepared a saturated stock solution of my compound in 100ml of water by dissolving it in excess and filtering out the undissolved sample. Then I ...
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### Calculate [Cr^3+] in equilibrium with Cr(OH4)- when 0.010 mol of Cr(NO3)3 is dissolved in a liter of solution buffered at pH 10.0

I tried setting up a RICE chart with the initial conditions being: \begin{array}{c|c} \hline \text{Species} & \text{Concentration / M} \\ \hline \ce{Cr^3+} & 0.010 \\ \ce{OH-} & 10^{-4....
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### Chile 2017, One of the Largest Fires in South America: Wood Ash Derivates for Industrial Applications [closed]

Hi: We're a group of people who wants to help people, domestic animals and wildlife recovering from this fire. Summary: We're having in Chile one of the largest fires in South American history. More ...
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### How to use C1V1=C2V2 How do the units work?

I am trying to do a dilution where I know I have 0.749 g/ mL and I want to use this concentration to calculate the grams of aspirin in each 100 mL solution. I am specifically worried about the units. ...
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### Titration to determine the amount of hydrogen peroxide

I have a mixture of sodium carbonate, sodium bicarbonate, ammonium carbonate, copper (II) sulfate, hydrogen peroxide, and sulfuric acid. I'm titrating potassium permanganate against this mixture to ...
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### Dilution question, “70 wt. % in H2O”? [closed]

If I have a solid and want to make an aqueous solution of 70%, how much water do I need? Is it as simple as weighing out 70 $\mathrm{g}$ of solid and adding water until I have 100 $\mathrm{mL}$? Will ...
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### Volume in decimetres cubed dimensional analysis

In chemistry class, we were learning about concentration, which is the number of moles of a substance per decimeter cubed of water, expressed as $\mathrm{mol} \cdot \mathrm{dm}^{-3}$. However, I was ...
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### How does dissolving a hydrate affect concentration?

Say I have 0.72 grams of calcium chloride dihydrate. If I dissolve it in water, the 2 water molecules attached onto it dissociates just like the $\ce{Ca^{2+}}$ and $\ce{Cl-}$, right? And if so, ...
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### Why is Ka constant when volume is increased?

The following graph shows $\ce{Ka}$ vs ${V}$ (Volume) at constant temperature, as ethanoic acid is diluted: However, I thought it would instead produce the following graph (see below). \$\ce{Ka=[...