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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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Calcute the dosage of aqueous extract to powder?

Can somebody explain to me how to calcute the dosage in powder? The powder (125 g) of each plant were macerated in 200 mL of distilled water for 12 h at room temperature and were then filtered to ...
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1answer
22 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 ...
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0answers
17 views

Dumas Method: How does the assumption that the unknown vapor is a real gas affect the determined molar mass? [on hold]

When performing an experiment with the Dumas method to find the molar mass, the assumption is that the gas is ideal. However, obviously, this is not the case, so how does the idea that the gas is not ...
0
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1answer
9 views

What is the relationship(when modelled in a graph) between the rate electrolysis of copper sulfate with a changing concentration [on hold]

I am aware that as the concentration of copper sulfate increases, the rate of electrolysis also increases. This is because of the increase of ions in the solution. What I am wondering is whether the ...
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0answers
54 views

Why is the y-intercept of a Beer's Law Plot not zero

In a general chemistry lab, we measured the absorbance of a known solution at various concentration and constructed a Beer's law plot. My line of best fit for my data was $y=123.31x+0.0894$ where $x$...
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0answers
17 views

Determine Rate Constant without Initial Concentration of First Order Reaction

This is the question I'm given: Methyl isonitrile isomerizes to acetonitrile: CH3NC(g) → CH3CN(g) at 215°C. The following data were collected during the process: Time (seconds) | [CH3NC] (mol/L) ...
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0answers
25 views

How much urea will separate out?

I have a question of solution chapter and I m having problem in both in solving as well as understanding that problem . The problem is: "One hundred grams of a $\pu{5m}$ urea solution is cooled to $...
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1answer
44 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 ...
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2answers
45 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
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1answer
78 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 ...
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1answer
100 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 ...
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1answer
52 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 ...
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1answer
22 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
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1answer
46 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)....
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1answer
102 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 ...
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1answer
84 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 ...
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1answer
33 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 ...
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0answers
13 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 ...
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0answers
46 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 ...
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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?
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1answer
26 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 ...
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3answers
68 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 ...
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1answer
394 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 ...
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1answer
43 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 ...
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1answer
32 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 ...
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1answer
21 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 ...
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1answer
118 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 ...
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0answers
44 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 /...
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2answers
45 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 ...
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32 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 ...
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3answers
73 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?
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1answer
535 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 ...
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2answers
79 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 ...
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1answer
946 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: $2\frac{k_1}{k_2}\ce{[NO2]}^2$ $2k_1\ce{[NO2]}^2-2k_2\ce{[N2O4]}$ ...
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1answer
184 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 ...
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2answers
70 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 $10^{-4.5}$. ...
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1answer
99 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 $K_a = 8.4 \times 10^{-4}$. ...
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1answer
573 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 ...
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2answers
71 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 ...
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0answers
87 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 ...
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1answer
45 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^{-}}\ \ \...
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0answers
48 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 (~$\pu{15 psi}$ @ $\...
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1answer
163 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 (...
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1answer
470 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 $X/V$?
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2answers
146 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 ...
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0answers
29 views

Standardising sodium hydroxide

Using an average titration volume of $\pu{26.8mL}$ of sodium hydroxide, calculate the concentration of the $\ce{NaOH}$ solution. ($\ce{NaOH}$ & $\ce{KH(C8H4O4)}$ molar ratio = $1:1$). Given that ...
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1answer
189 views

Acetic acid in vinegar [closed]

How do I calculate the number of moles of acetic acid present in 25 mL of a 10% vinegar solution?
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0answers
35 views

Is is possible to Generate ~1ppm Copper in Solution from Elemental Copper? [closed]

I am designing a hydroponic system and need to control algae. Copper is a known algaecide and lettuce actually needs some copper to grow well. I had read stories about people using copper pennies in ...
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260 views

The effect of temperature increase on sodium hypochlorite concentration in bleach

We are completing an experiment on the effect of temperature increase on sodium hypochlorite concentration in bleach (as calculated using excess iodine and sodium thiosulfate titration) I assume ...
3
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1answer
46 views

Two different methods to express the equilibrium constant give different results

$\pu{2.0M}$ of $\ce{I2}$ and $\pu{2.0M}$ of $\ce{Br2}$ are initially present in a reaction mixture. Calculate the equilibrium concentration of $[\ce{I2}]$ , $[\ce{Br2}]$ and $[\ce{IBr}]$ at $\pu{425K}$...