Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

-1
votes
0answers
25 views

How do I quantify the changed concentration of HCL when diluted with water [on hold]

So take this hypothetical situation whereby you are given 1M of $\ce{HCl}$ (hydrochloric acid) and you are conducting an experiment to determine the effect of change in concentration. You take 5ml of ...
-1
votes
0answers
20 views

Find concentrations of Sodium Acetate and Acetic Acid to create buffer solution [on hold]

The stockroom contains 1M $\ce{NaOAc}$ (Sodium Acetate), 1M $\ce{CH3COOH}$ (Acetic Acid), distilled water, and strong acids and bases. You need to create a buffer solution that has a pH of 4.75 such ...
0
votes
0answers
9 views

How do I calculate the concentration using volume and absorbance? (Beer's Law) [duplicate]

Dilute the stock solution of KMnO4 to create several other sample solutions of known molarities. Fill in the data table below with the known concentrations.
-4
votes
0answers
26 views

AP CHEMISTRY QUESTION (BEER'S LAW) [on hold]

Your teacher instructs you to determine the concentration of a sample of potassium permanganate (KMnO4) which is violet purple in solution. a. First, you use a 100 mL volumetric flask to create a 0....
-2
votes
1answer
35 views

What is the ppm of this solution and how does one decipher what it means? [closed]

What is the concentration of a solution, in parts per million, if 0.02 g of NaCl are dissolved in 1000 g of solution? I think it comes out to 20 ppm. I am confused on what ppm means tho. So 20 ppm ...
-2
votes
0answers
16 views

Solving for PPM Concentrations [closed]

What is the concentration of a solution, in parts per million, if .02mg of NaCl are dissolved in 1000g of solution?
-1
votes
1answer
23 views

What is PPM in terms of air concentration?

When they say the $\ce{CO2}$ concentration is $\pu{350 ppm}$ what does this actually mean? Does this mean that if we took a sample of air say $\pu{1 m3}$ then $\pu{350 mg}$ of that cubic meter would ...
-1
votes
1answer
26 views

Does molarity change if you decrease volume?

For example if the solute of the solution contains $\pu{0.5 mol}$ and the total volume is $\pu{0.5 L}$, the molarity would be $\pu{1M}$. But if I take a portion of that solution, let's say $\pu{0.1 L}$...
-2
votes
1answer
45 views

How to derive rate law expression for inversion of sucrose with changing pH?

I came across a question worded as follows- "The inversion of cane sugar proceeds with half life of 50 minutes at pH=5 at any concentration of sugar. However, if the pH=6, the half life changes to 500 ...
3
votes
1answer
34 views

Homemade spectrophotometer to exemplify Beer-Lamberts law

I have built a 12-band spectrophotometer, and i'm currently keen on proving Beer-Lamberts law through a small practical example. The solution that I'm going to test with my spectrophotometer, is ...
1
vote
1answer
31 views

Diluting topical cream (10%)

I need to dilute a face cream with 10 % active ingredient to 2.5 % and 5 % but I am confused as to how. I looked into the $$c_1V_1=c_2V_2$$ and $$\text{concentration of a solution}=(\text{amount of ...
-1
votes
1answer
176 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 ...
-1
votes
1answer
51 views

How to determine the volume of water necessary to produce a solution with 4.9 g/l sulfuric acid?

The molar mass of sulfuric acid is $M(\ce{H2SO4}) = \pu{98.1 g/mol}$. We have $\pu{100 mL}$ of a $0.1$ molar solution of sulfuric acid. What volume $V$ in $\mathrm{mL}$ of water, $\ce{H2O}$, do we ...
-2
votes
2answers
73 views

Is the mole fraction equal to the weight fraction?

Whenever there is a reaction is excess of air it is customary to assume mole ratio of $\ce{N2}$ to $\ce{O2}$ as $79/21$. However, in another reaction which states that it will contain $\pu{1 wt\%}$ of ...
2
votes
1answer
80 views

How to determine the proton concentration in the following solution in mol/L? [closed]

A $\pu{0.8L}$ solution contains $\pu{0.60 g }\ce{ NaOH}$ in water. Then the above question follows. It's been a long time that I made some chemistry exercises. Now I'm stuck with a couple of ...
0
votes
1answer
105 views

should charge balance be based on activities?

We have a fluid with $\pu{0.01 M}~\ce{HCl}$ and $\pu{0.02 M}~\ce{K2HPO4}$, so if we assume activity coefficients are $1$ throughout we can find pH as $6.800012$ and confirm that at that pH there is ...
1
vote
1answer
64 views

Maximum Concentration of Benzene possible

A question for my PhysOrg course states: Assume you are performing a reaction in which benzene is a reagent. What is the maximum concentration of benzene possible? Hint: what facts do you need to ...
0
votes
1answer
28 views

How many samples would be worth when following a desorption? How to relate with limit of detection?

I am following the desorption of a compound from a polymer. Let's imagine that it occurs at a certain rate and most of the compound is desorbed after 5 days (as in the figure). Then, I could use many ...
2
votes
1answer
50 views

Why does water diffuse from a lower solute concentration to a higher one?

I'm studying biology and this came up in the context of passive transport. I understand why, in general a gas moves down a concentration gradient (the random movement of gas particles and probability)....
0
votes
1answer
300 views

When using a “dilute hydrochloric acid” solution, how diluted should it be?

Quite often when reading through some instructions or documentation or an outline that I've found online (EG: acid-base extractions), theres a step that involves using a "dilute hydrochloric acid ...
0
votes
1answer
106 views

Calculate mass concentration of Ca(OH)2 solution

Can anyone help me calculate the mass concentration of $\ce{Ca(OH)2}$ solution with molar mass $\pu{74.1 g/mol}$ at the $\pu{pH of 12.8}$. My work so far: From the pH I get the molar concentration ...
1
vote
1answer
41 views

Amount concentration versus number concentration

The IUPAC Gold Book defines Amount concentration Amount of a constituent divided by the volume of the mixture. Also called amount-of-substance concentration, substance concentration (in ...
0
votes
0answers
15 views

EQPt pH of a Monoprotic Acid-Base Titration: Product of Molarites Over Their Sum

Context The Henderson-Hasselbalch equation is as follows. $$pH=-\log\big(K_a\big)+\log\bigg(\frac{[A^-]}{[HA]}\bigg)$$ One may follow its derivation in order to understand how it came to be, yet ...
1
vote
0answers
52 views

Calculate concentrations in a system made up of molecules in order to calculate ionic strength

I understand how to calculate ionic strength where there are concentration data in molality or molarity units available and where the system is made up of only two components. However, I have been ...
0
votes
2answers
50 views

Does sheer amount affect reaction rates?

For example, in the iodine and starch reaction, if I use 20 mL of a set concentration of each, will it be slower to completion if I use 40 mL of each at the same concentration?
-1
votes
1answer
29 views

Diluting two solutions together

I have two different mixtures: 1 gallon of "A mixture", which is 99% substance A and 1% water An arbitrarily large supply of "B mixture", which consists of 4% substance B and 96% water. How do I go ...
-1
votes
3answers
74 views

What is the difference between “adding a liquid” and “diluting to a liquid”?

Place $\pu{20.0 g}$ $\ce{NaOH(s)}$ in a flask and dilute to $\pu{1.00 L}$ with water. Place $\pu{20.0 g}$ $\ce{NaOH(s)}$ in a flask and add $\pu{1.00 L}$ of water. How exactly do these two ...
-1
votes
1answer
829 views

Does the concentration affect the voltage in electrochemistry

Hello for my final chemistry lab we are doing electrochemistry. For my independent lab I'm using 10mL of ZnSO4 and 10mL of CuSO4. Then connect them with a salt bridge. I connect Zn metal and Cu metal ...
0
votes
1answer
50 views

Calibration Ammonia Sensor and Gas Concentration

My name is Felipe and this is my first post here. I'm working on a project to calibrate an electrochemical ammonia sensor. But I have a lot of doubts because I am a layman in chemistry. I'll list them ...
0
votes
1answer
35 views

How to meausre ion interferences in solution?

Is there a way to quantitatively measure the interference of different metal ions in solution? I plan to measure concentration of Pb(II), Fe(II), and Cu(II) in solution together using a ...
-1
votes
1answer
25 views

Find volume of sample such that it contains 100ng of DNA

Im struggling with the maths of concentrationsand volumes and things..Ill give the question, then my thoughts on it: A DNA trimer strand, ab, has moleuclar weight of $9309ng/\mu mol$. I#m designing a ...
3
votes
1answer
160 views

Percentage purity of Ba(MnO4)2 sample that completely reacts with given H2O2?

$\pu{40 g}$ $\ce{Ba(MnO4)2}$ (mol. wt. = 375) sample containing some inert impurities in acidic medium is completely reacted with $\pu{125 mL}$ of $\pu{3 M}$ $\ce{H2O2}$. What is the percentage purity ...
1
vote
0answers
57 views

How to convert from ppm to ug/m3 in case of PMx?

For $\text{PM}_{10}$, $\text{PM}_{2.5}$ sensors, sensitivity, minimum and maximum recordable concentrations are generally expressed in $\pu{ppm}$ (parts per million) while legislation uses $\pu{\mu g /...
-1
votes
2answers
55 views

Do we consider the dissociation of water when dealing with ion concentrations of a solution?

One mole of hydrated copper(II) sulphate, $\ce{CuSO4 . 5 H2O}$, is dissolved in water. How many moles of ions does the solution contain? 1) 1 2) 2 3) 6 4) 7 The ...
0
votes
0answers
33 views

Why are the results of two methods different for calculation LOD and LOQ?

I calculated the Limit of Detection (LOD) and Limit of Quantification (LOQ) with results (Table 1) obtained from HPLC (spiked muscle sample). For this purpose, I used regression analysis and two ...
1
vote
3answers
75 views

If i keep adding sulfuric acid into water, will it keep dissolving forever?

If i keep adding sulfuric acid into water, will it keep dissolving forever?
5
votes
1answer
624 views

What's the relation between molarity and molality?

I am trying to derive the relation between the molarity and molality of a solution Mole concept $\displaystyle n = \frac{M'}{M''}$ Here, ($n$) stands for number of moles $\ce{(M^{'})}$ stands for ...
1
vote
2answers
193 views

How to calculate molarity of a solution by solving the percentage?

Molarity is number of moles per litre of solution and we calculate it by simply dividing moles by volume. But, if moles are not given and the w/w or w/v percentage is given then, how can we solve for ...
3
votes
1answer
1k views

How do I solve questions pertaining to rate of disappearance and appearance?

In a reversible reaction $\ce{2NO2 <=>[$k_1$][$k_2$] N2O4}$, the rate of disappearance of $\ce{NO2}$ is equal to: $2\frac{k_1}{k_2}\ce{[NO2]}^2$ $2k_1\ce{[NO2]}^2-2k_2\ce{[N2O4]}$ ...
3
votes
1answer
270 views

Catalyst with zero order kinetics

I've read in a book that a catalyst may be included in the rate equation even though it is never used up. It was written as having zero order kinetics however I thought catalyst concentration will ...
-3
votes
2answers
87 views

What is the ionization constant, $K_a$, of the acid?

A 0.45 M solution of a weak acid, HX, has a pH of 4.5. What is the ionization constant, $K_a$, of the acid? Attempt at solution: [HX] is already given as 0.45 M. [H+] is given by $10^{-4.5}$. ...
0
votes
1answer
124 views

What is the citric acid concentration, [HCit], in the lemon juice?

The pH of lemon juice is about 2.1. What is the citric acid concentration, [HCit], in the lemon juice? I am given that $HCit \leftarrow \rightarrow H^+ + Cit^-$ and that $K_a = 8.4 \times 10^{-4}$. ...
-1
votes
1answer
858 views

Calculating the pH upon titrating barium hydroxide and hydrochloric acid

Question: Calculate the pH produced from mixing $\pu{25.0 mL}$ of $\pu{0.420 M} $ $\ce{Ba(OH)_2}$ with $\pu{125 mL}$ of $\pu{0.120 M}$ $\ce{ HCl}$. Attempt: I'm learning about acids and bases ...
-1
votes
2answers
94 views

Diluting Stock Solution with NaOH

So I know that if you want to dilute a stock solution to a smaller concentration you simply use the $M_1V_1 = M_2V_2$ equation where the $M_1$ and $V_1$ are the molar concentrations and volumes of the ...
1
vote
0answers
101 views

How does the molarity of a solution change on boiling off the solvent?

The dilution equation $$M_1V_2=M_2V_2$$ is an equation that can be used to calculate how adding water can impact the volume and molarity of a solution. So I was wondering if this equation would apply ...
1
vote
1answer
51 views

Confusion about the ICE table

Calculate the pH of a $\pu{2M}$ $\ce{H_3PO_4}$.Calculate the equilibrium concentrations of $\ce{H_3PO_4 , H_2PO_4^{-} , HPO_4^{2-}}$. First equation: $\ce{H_3PO_4 <=> H^{+} + H_2PO_4^{-}}\ \ \...
1
vote
0answers
61 views

What are the optimal conditions for the complete acid hydrolysis (using HCl) of potato starch? [closed]

I'm hoping someone can provide the specifics on the optimal conditions required for the complete acid hydrolysis (using $\ce{HCl}$) of potato starch? I will be using an autoclave (~$\pu{15 psi}$ @ $\...
1
vote
1answer
210 views

Equilibrium change in sealed container

Question: Decreasing the product's concentration seemed to follow the logic of Le Chatelier's principle, so a decrease in volume will force the reaction to the left to increase the pressure (...
1
vote
2answers
802 views

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 $X/V$?
1
vote
2answers
181 views

Calculation of molarity using dilution equation [closed]

Using the formula $C_1V_1 = C_2V_2$ I am supposed to calculate the molarity of dilutions. The original solution is $\pu{0.100 M}$ at $\pu{10 mL}$. I diluted it by mixing a $\pu{7.50 mL}$ stock ...