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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131 views

How do I find a concentration from a sample tested on a spectrophotometer?

I have an assignment to calculate the concentration from a sample. The assignment is: You have 100 µL of RNA. You take 10 µL from the sample and put it in 990 µL of water in the cuvette. The OD is 0....
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Adding concentrations to obtain mass

I have a question that gives two concentrations and asks for the mass of HCl formed by the reaction. I have two concentrations: 250mL of 4.00M $\ce{H2SO4}$, and 250mL of 1.00M $\ce{NaCl}$. Here is ...
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Making a solution with two solutes

I need to make a solution that has a 15% (wt/wt%) HCl acid concentration and a 6% (wt/wt%) NaI concentration. I'm not sure yet how much of this solution I will be required to make so a general recipie ...
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Determine the concentration of the original NaOH solution

This was a question on the mt exam two days ago : A chemist added 40.0 mL of an $NaOH$ solution to 90.0 mL of 0.400 M $HCl$. The solution was then treated with an excess of $\text {nickel(II) ...
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How can I find out the concentration of chlorine in an acid bath?

A professor I have gave the class this question, can anyone help? This is the first part of the question. (Also, my professor is from Bangladesh...so yea...) It's the year 2395, and the world is in ...
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Molarity to Percent, Mole Fraction, Molality

I have a series of questions similar to the following. I want to make sure I do this correct before I do the others. I am in need of a hint. ...
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Molality and dissociation

For $\ce{HCl(aq) -> H^{+}(aq) + Cl^{-}(aq)}$, if $\ce{HCl}$ has a concentration of 1 molar then $\ce{H+}$ and $\ce{Cl-}$ also have 1 molar. But for $\ce{HF(aq) <=> H^{+}(aq) + F^{-}(aq)}$, if ...
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Increasing mass

I'm watching a video, and the speaker states that the molality formula is better than the molarity formula because it is more constant, since molarity deals with volume and molality deals with mass. ...
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Determine Cu+2 and SO4-2 concentration using Potentiometry?

The title says it all. I've been researching as well but all I could come close was solid state ion selective electrodes. Could someone please help me out? There should be two methods(or one) to ...
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How to calculate m/e value for the base peak in mass spectroscopy?

My working out: Propan-1-ol : CH3CH2CH2OH This can be broken up into: CH3 + CH2CH2OH CH3CH2 + CH2OH CH3CH2CH2 + OH Base peak = most abundant fragment formed (highest peak) How do i know which ...
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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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How many grams of CH3OH can be made from 30.0g of CO if it all reacts? [closed]

Once made by heating wood in the absence of air, methanol ($\ce{CH3OH}$) is now made by reacting carbon monoxide and hydrogen at high pressure: $\ce{CO_{(g)} + 2 H2_{(g)} -> CH3OH_{(l)}}$ How ...
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What is a complete reaction?

For a lab assignment, I combined $\pu{10 mL}$ of $\pu{1 M}$ sodium sulfate solution with $\pu{10 mL}$ of $\pu{1 M}$ calcium chloride solution. The ionic equation I came up with is: $$\begin{multline} ...
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Concentrations of mixed solutions

If I mix a $\pu{2 M}$ solution with a different $\pu{1 M}$ solution, do the individual solutions reduce in molarity to $\pu{1.33 M}$ and $\ce{0.33 M}$ respectively?
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Why do solutions become saturated?

Why can a solvent dissolve only a particular amount of solute? If we add more solute to the solution, the number of solute particles in contact with water increases. So rate of dissolution should ...
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Photosynthetic rate calculation

What are the steps in calculating the photosynthetic rate ($\mu\text{mole}\ce{O2}/$ $\text{m}^2 / \text{min}$) for a leaf that has an area of $0.0025 \text{m}^2$ and a $\ce{O2}$ evolution rate of $...
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How do I create a concentrated solution of singlet oxygen (in the dark)?

Without appealing to reactions that require photons / light, how do chemists achieve a very high concentration of continually produced, though quite short lived, singlet oxygen in aqueous solution (i....
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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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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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Molarity exercises [closed]

Can anyone direct me to a good book with lots of molarity exercises, i really want to practice this and would like to find as many types of exercises involving molarity. I of course did google this ...
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I need to make a solution with a specific concentration. How do i find the mass?

I have to make a 250 mL solution of $\ce{Mg(NO3)2}$, the concentration of the solution has to be 0.3 mol/L. How can I find out the mass of how much $\ce{Mg(NO3)2}$ I need to use?
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$\beta$-mercaptoethanol molarity

I'm writing up a practical and $\beta$-mercaptoethanol was used, with no concentration given. I've found I don't need the BME molarity since I'm giving percentage (v/v) concentration, however I'm ...
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How should I modify my molecular dynamics simulation so that known chemical reactions can be modelled?

I have written some molecular dynamics code that I want to use to model known chemical reactions. By known I mean that it has been observed in a lab that $\ce{A +B->C}$. I am not interested in ...
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Finding molar mass of an unknown acid

"In the titration of a solid acid, an endpoint is reached after 22.0mL of 0.120 M $\ce{NaOH}$ has been added. Assuming that each acid particle contains two acidic hydrogens and both are ...
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What does this scale mean?

$$\log_{10}~\mathrm{pg}/\mathrm{ml}$$ I do not understand the scale. How do I convert this to a standard concentration (without the logs)?
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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 ...
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Why do some solutions eventually stop boiling and start “popping” as they get more concentrated?

A very long time ago I performed an experiment in my kitchen, part of which was to remove all water from a solution. Unfortunately I don't remember what was in it, but the point is that as the ...
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Basic chemistry equation with ammonia [closed]

A table in the book 'Chemistry NCEA Level 1' has 4 headings, the first of which is 'Volume (mL) ammonia solution provided (conc 2 g L-1)' Could someone please provide a comprehensive explanation of ...
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What do the different grades of chemicals mean?

When purchasing chemicals from Sigma, Fisher, or wherever, there are often -grade's attached to their description like reagent-grade, technical-grade, analytical-grade, or more niche-sounding biotech-...

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