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Questions tagged [mole]

The mole is a standard amount of a substance A mole of a substance is a number of units (particles, atoms, molecules, ions, peas, hard candies, people, universes) equal to the number of atoms of carbon-12 in one gram of carbon-12, or an Avogadro's number of stuff. The mole allows us to relate real-word measurements to atomic scale phenomena.

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How can I calculate number of moles introduced into the ractor? [on hold]

-''- From avarge reaction rate? For example I got avarge reaction rate equal to 0.0005 mol/dm^3*s and substrate concentraction equal to 0.8M
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Calculate the number of moles introduced into the reactor [on hold]

How can I solve this ? In a 5 L reactor, reactions were carried out and it was found that after 30 minutes the average reaction rate was 0.0005 mol/l*s and the substrate concentration was 0.8M. ...
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0answers
27 views

Why there is a need of independent definitions for both mass and mole?

Considering that the two quantities are linked by reality, how can be both imposed by independent definitions? I am aware that the change taking place next May does not effect common weighing in ...
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2answers
35 views

Help required for the calculation of moles [closed]

If 4.5ml of yeast prep + 0.5ml of 0.25 M glucose is separated into 2ml in 2 similar flasks. How many micromoles of glucose are there in one flask? Using M1V1=M2V2 (0.5ml/1000)*0.25M = M2 * 2ml = 0....
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1answer
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Why has the mole been redefined for 2019?

The mole is still defined as an SI unit representing the number of constituent particles (whether they be atoms, molecules etc.) in 12 grams of carbon isotope 12 (carbon-12). Effective from May 20 ...
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3answers
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An aqueous solution of NaCl has a mole fraction of 0.21. What is the mass of NaCl dissolved in 100.0 mL of solution? [closed]

Work mole fraction of NaCl = 0.21/0.21+0.79 If there is 1 mol of total solution, there will be 0.21 mol NaCl and 0.79 mol H2O 0.21 mol NaCl = 12.27 g 0.79 mol H2O = 14.23 g this would yield a ...
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4answers
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What is the smallest molar volume?

I wondered how small a volume a mole of material could occupy, so I started with carbon, which would need 12 grams. That's 60 carats, and there happens to be a famous 60 carat diamond. If my density/...
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2answers
131 views

Molar mass vs molecular mass [duplicate]

Why is that molar mass has of a substance, which is the mass of one mole of a substance ($6.02\times 10^{23}$ particles of that substance) has the same value as molecular mass, which is the mass of ...
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1answer
25 views

How to apply the Principal of Atom Conservation (POAC) [closed]

27.6 g $\ce{K2CO3}$ was treated by a series of reagents so as to convert all of its carbon to $\ce{K2Zn3(Fe(CN)6)2}$. Calculate the weight of the product. I am asking here is that, why we are ...
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1answer
29 views

Does 1 mole have the same molar mass? [closed]

I have tried to look it up, and find answers, it really intrigues me!
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1answer
43 views

Confusion between moles and molarity units

I am a total newbie in the field and i would like some kind of guidance. So, I have been recently given 2 datasets with measurements regarding several phospholipid fatty acids of plasma HDL. Both ...
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1answer
27 views

Quantity of base needed to neutralise litre of 36% HCl?

Sorry for asking a basic chemistry question. I last did this kind of chemistry at school about 30 years ago and I don't have confidence that I'd get it right from first principles :) Short version: ...
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0answers
29 views

Effect of redefining Avogadro's constant and kilogram on molar mass

Avogadro's constant $N_A$ is defined as the number of constituent particles (usually atoms or molecules) contained in the amount of substance given by one mole. The value of Avogadro's constant $N_A$ ...
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1answer
57 views

I have a question involving a mole calculation which I was able to answer but took me a whole page. Whats the most efficient way of answering it? [closed]

A 10.00g, mixture of potassium carbonate and potassium hydrogen carbonate is heated to constant mass. The final mass was found to be 8.90g. calculate the % composition of the original mixture. My ...
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3answers
46 views

Question about the mole [duplicate]

Why is it to get from x amu---->xgram you need a mole of the substance. I mean I underdstand this to be the case for Hydrogen. Why does a mole of a substance CONVERT the substances amu into grams?
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1answer
57 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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1answer
20 views

Molarity of a substance in a solution when more fraction is given

Mole fraction of ethanol in a solution with water is $0.040$. What will be the molarity of ethanol in water? Density of water can be assumed to be $1\ \mathrm{g/mL}$. This is how I tackled the ...
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1answer
144 views

How are the molar mass and molecular mass of any compound numerically the same?

This observation is really annoying me, and the internet isn't providing me with any solid answers. Either their definitions of molar mass completely differ, or they don't stick to their own ...
2
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2answers
158 views

Does a stoichiometric coefficient represent molecules or moles of a substance?

I understand that the one mole of atoms is equal to $6.02\times10^{23}$ atoms. However, when I used various resources to learn about stoichiometry, they showed me a balanced equation: $$\ce{2H2O->...
3
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1answer
89 views

Is it possible for me to derive Avogadro's number?

To my understanding the mole is the unit used to translate between mass on the atomic level and mass in the macro level, defined as the number of atoms in $12$ grams of Carbon-$12$, which apparently ...
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1answer
73 views

How did early chemists measure mass of atoms?

Here a book says that Berzelius measured atomic masses using a simple lab and his measurements was so close to modern results. Can someone explain how a person living in 19th century was able to ...
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1answer
41 views

Is there a formula for density of any gaseous substance just based on its molar mass?

$\pu{112 ml}$ of hydrogen combines with $\pu{56 mL}$ of oxygen to form water. When $\pu{224 mL}$ of hydrogen is passed over heated cupric oxide, the cupric oxide loses $\pu{0.160 g}$ of its weight. ...
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0answers
48 views

Calculating amino acid mol/mol ratios

I am trying to understand how the authors calculated the TRP/LNAA (mol/mol) ratios in Table 1 in this paper. For example, when I calculate the TRP/LNAA (mol/mol) ratio for HPROT, I get 0.14 instead ...
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1answer
152 views

How to find the percentage composition of halogen using Carius method?

In the formula: $$\text{Percentage}=\frac{\text{atomic mass of halogen}}{\text{molecular mass of Agx}}\frac{\text{mass of AgX}}{\text{mass of compound}}\cdot100$$ here mass of compound is the mass ...
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2answers
92 views

Volume of composition of air

My teacher stated: At standard conditions, 1 liter of air at 21% oxygen possesses $\pu{0.21 L}$ of oxygen. Since at STP, 1 mole of gas occupies $\pu{22.4 L}$, simply divide $0.21/22.4$, to arrive ...
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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 ...
4
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0answers
108 views

Is Avogadro's number an integer? [duplicate]

I have heard that Avogadro's number, $N_\mathrm A=6.022 \times 10^{23}$, is the number of atoms contained in $12$ grams of $\ce{^{12}C}$. I think it should be an integer, but I couldn't find the exact ...
4
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2answers
264 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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1answer
561 views

Why does 1 mol. of any gas at STP occupy only 22.4L Volume when it should occupy the volume of entire container in which it is kept? [duplicate]

Let us say we have a container of 100L capacity and a gas inside it is kept at STP. According to the law the gas should occupy only 22.4L of volume but shouldn't the gas occupy the entire volume of ...
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1answer
217 views

Calculating the Radius of a Molecule

Assuming the molecule is a sphere, would the radius of amylopectin be $9.17*10^{-22}~cm^3$? I arrived at this answer by deriving the molar volume by dividing the molar mass ($828.72~g/mol$) of ...
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Calculation of Molar Mass

What is the molar mass of whey protein isolate? I already know that whey protein consists 70% of β-lactoglobulin (18.3 kDa) and (30%) of α-lactalbumin (14.2 kDa), however, as their molecular weights ...
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1answer
794 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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1answer
1k 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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Why isn't the sum of the volume of the reactants the same volume as product?

Imagine that we needed to work out the volume of $\ce{SO2 and O2 that would produce 0.180dm^3 of SO3}$ $$\ce{2SO2 + O2->2SO3}$$ By using Volume = Moles$\mathrm{~ \times 24 ~dm^3}$ We can ...
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1answer
116 views

What to say 'one mole of C atoms or one mole of C molecules?

What to say 'one mole of C atoms or one mole of C molecules in CO? Please point out if I am wrong here As we know, one molecule of CO = one mole of CO molecules = 6.223 X 10^23 number of CO molecules ...
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1answer
70 views

Does mass equal to moles times molar mass take into account coefficients?

I have an equation $$\ce{ 2NaN3 -> 2Na + 3N2}$$ I've calculated there are $\pu{4.4 moles}$ of $\ce{N2}$ (using the data given in the question). I then did $\large{\frac{4.4}{3 \cdot 2}}$ to get ...
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1answer
82 views

Calculate the formula, and moles

If $\ce{1.84\times10^{-4}}$ moles of element A was completely reacted with element B to create $\ce{1.231\times 10^19}$ molecules of $\ce{(A3B2)_x}$ a hypothetical compound, what is the value of x? I ...
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1answer
262 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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2answers
7k views

Avogadro's Number: 6.023 x 10^23 or 6.022 x 10^23? [duplicate]

I was taught that Avogadro's number was $6.023 \cdot 10^{23}$. Now, the accepted value is allegedly $6.022 \cdot 10^{23}$. Has there been a change? If so, when and why? There are still some sites that ...
2
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1answer
201 views

How to define equivalents here

$3g$ of activated charcial was added to $50 ml$ of acetic acid solution ($0.06N$) and filtred after an hour and it was found to be $0.042 N$ .The amount of acetic acid adsorbed (per gram of charcoal) ...
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1answer
50 views

Where am I wrong in my calculations? [closed]

I am revisiting the concept of mole and I decided to figure out random values (for instance: mass of 1 molecule of water) to see how much I understand the concept of moles and how it relates to amu. ...
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1answer
94 views

Mass of iron from the reduction of iron(III) oxide [closed]

Given the equation $$\ce{Fe2O3 + 3H2 -> 2Fe + 3H2O},$$ determine how many grams of $\ce{Fe}$ can be produced from $\pu{16.5 g}$ of $\ce{Fe2O3}$. I've already determined the masses of each ...
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118 views

Validity of Law of Equivalence

Is law of equivalence valid for partial displacement reactions? 【I found this in my textbooks: According to the law of equivalence, whenever two substances react, the equivalents of one will be equal ...
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2answers
116 views

Neutralization of alkali solution by a mix of strong acids

$\pu{0.1 M}$ $\ce{HCl}$ and $\pu{0.2 M}$ $\ce{H2SO4}$ solutions are mixed in equal volume. This solution is diluted to double the volume. Find the volume of $\pu{0.1 M}$ $\ce{NaOH}$ which can be ...
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1answer
290 views

Propane-water molar ratio [closed]

Propane gas, $\ce{C3H8}$, burns in oxygen to produce carbon dioxide and water vapour as follows: $$\ce{C3H8 (g) + 5O2 (g) = 3 CO2(g) + 4 H2O (g) + \pu{2200 kJ}}$$ If $\pu{1.5 mol}$ of ...
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1answer
246 views

Mass of chromium in ammonium dichromate

What mass of chromium is in $\pu{100 mL}$ of $\pu{0.0400 mol/L}$ $\ce{(NH4)2Cr2O7}$? The specific concept is how to find the mass of a certain ion/element in a substance, given the concentration. I ...
2
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2answers
131 views

A mole of atoms is the number of atoms whose total weight equals the atomic weight?

My textbook says, a mole of atoms is the number of atoms whose total weight = the atomic weight. There's something in the definition that's confusing me. Now what is confusing me is: Atomic weight =...
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1answer
837 views

Confusion in n-factor calculation

How do we calculate the equivalent weight of a compound, in a case where certain fraction of an element of the compound is getting reduced, while the other fraction is unaffected (no change in ...
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1answer
205 views

Isotopic mass to density

I want to figure out/calculate the density ($\pu{g/cm3}$) of the various isotopes, here $\ce{^109Ag}$. I know it's isotopic mass is $\approx109$ and calculated the number of particles/gram. But I ...
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1answer
54 views

How do I find the number of grams of the product when given reactants? [closed]

I have the following chemical equation $$\ce{H + O2 -> H2O}$$ which balances out to $$\ce{4H + O2 -> 2H2O}$$ How would I find out how many grams of $\ce{H2O}$ and $\ce{H}$ I have, if I ...