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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Different method of solving a question giving different answer [closed]
Calculate the concentration of nitric acid in moles per litre in a sample which has a density, $\pu{1.41 gmL^–1}$ and the mass per cent of nitric acid in it being $69 %$.
I attempted to consider a 1L ...
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How to change molarity of hydrate group? [closed]
I am making stock solutions for an algal growth medium. One solution calls for dissolving 9 g of MgCl2 4H2O (Magnesium chloride tetrahydrate) to 50 mL of distilled water in an autoclaved bottle. My ...
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How do I find the amount of moles from the amount of units?
The problem:
Find out the amount of moles of a certain substance knowing that the amount of units of said substance is $\pu{1.8E23}$. I have to find how many moles of carbon, hydrogen, and oxygen that ...
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When a gas is expanded, why doesn't the number of moles of a gas increase despite it's volume increasing (doubt in JEE sample question) [closed]
This question might be elementary, but it is genuine. I realise that some users might downvote the question for being so basic, but I urge them to be a little merciful, and help out a confused high ...
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How to calculate carbon to phosphorus stoichiometric ratios using results from ICP-MS and CHN analyzer?
I run a few chemostats to manipulate the carbon to phosphorus ratio (C:P) of algae, which is later feed to an invertebrate. I used Inductively coupled plasma mass spectrometry (ICP-MS) and Inductively ...
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A reaction based question from stoichiometry [closed]
A 110.0g sample of a mixture of CaCl2 and NaCl is treated with Na2CO3 to precipitate the Calcium as Calcium Carbonate. This CaCO3 is heated to convert all the Calcium into CaO and the final mass of ...
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Redefinition of mole 2019
The mole was redefined in 2019 to $6.02214076\times 10^{23}$ elementary entities. I've learnt that this means that the mass of one mole of Carbon 12 is now no longer exactly 12g. However isn't ...
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Finding concentration of ascorbic acid
Question:
A person applied following procedure for the determination of ascorbic acid (Vitamin C) in a sample solution.
A volume of 20.00 cm3 of the ascorbic acid sample was reacted with 25.00 cm3 of ...
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Even in an acidic solution with a pH equal to 0, there are only 1 mol/L H3O+ ions, while there are approx. 54 mol/L water molecules
I find this sentence in my high school chemistry book to be confusing:
"Even in an acidic solution with a pH equal to 0, there are only 1 mol/L H3O+ ions, while there are approx. 54 mol/L water ...
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Definition of Avogadro's constant
I've read this excerpt from Wikipedia countless times, but I'm still confused:
The Avogadro number is the approximate number of nucleons (protons or neutrons) in one gram of ordinary matter.
Shouldn'...
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Can the number of moles be a ratio of mass percentage and molecular mass? [closed]
I recently started studying mole concept and came across this formula,
$$ n=\frac{\text{mass percentage}}{\text{molecular mass}}$$
I don't know how it came into existence. How does this formula work?
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Can a reaction produce more products than reactants? [closed]
Q:What volume of propane is burnt for every $100 \mathrm{~cm}^{3}$ of oxygen in the reaction?
$$
\mathrm{C}_{3} \mathrm{H}_{8}+5 \mathrm{O}_{2} \rightarrow 3 \mathrm{CO}_{2}+4 \mathrm{H}_{2} \mathrm{O}...
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How did we find relative atomic masses in 18th century or early 19th century? [duplicate]
The atomic masses of atoms or relative atomic masses were known in the 19th century.
But how did they actually calculate that relative atomic mass?
What I think is that if we have a sample of an ...
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What is the dimension of molar mass?
I was told that the number of moles is ‘dimensionless’. Does this mean that the dimension of molar mass is simply mass and hence the unit g/mol can be expressed as equal or proportional to the dalton?
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Using the mole ratio to figure out the molecular formula [closed]
It takes $\pu{8.0 cm^3}$ of aqueous sodium phosphate to fully react with $\pu{12.0 cm^3}$ of an aqueous solution of the nitrate of metal $\ce{T}$. If both solutions have a concentration of $\pu{1 mol ...
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What is the cheapest way to give someone 1 mol of gold? [closed]
Let's say I've lost a bet to a friend who is a molecular biologist and I have to give her 1 mol of gold. What is the cheapest way to accomplish this?
It was a fun bet so I don't need to give her the ...
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What volume does CO2 converted from O2 have?
Let's say a human inhales air that contains exactly 1 Liter of pure O2 (about 4.76L regular air) and no CO2. All at normal pressure.
They manage to hold their breath until all the O2 has been ...
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Doubts regarding Mole concept and Avogadros number [closed]
So I am really confused about simple topics like mole and Avogadro
Here is my oversimplified view
So mass of 1 atom of elements in grams was not in whole numbers and it was difficult using em for ...
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What is the difference between mole and molar mass?
In my book it says 1 mole of carbon =1gram atom of carbon =12 gram if I see this relation that seems to me that 1 mole is mass of an atom In grams.
But molar mass is different and why we use for ...
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Molar mass question
Molar mass of oxygen is 16g/mol , but O2 is 32g/mol , it is shows that 32 gram per 1 mol ,but if we add 1 mol oxygen and one mol of oxygen , shouldn't it be 32 gram per 2 mol for dioxygen ?
it doesn't ...
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Is Avogadro's constant equal to 1? [closed]
The mole is defined to be exactly $\mathrm{mol}=6.02214076\cdot 10^{23}$ entities. Avogadro's constant is defined as $N_A=6.02214076\cdot 10^{23}\mathrm{mol}^{-1}$.
Then why is it not usual to write
$$...
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Calculating molarity of iodine solution after reaction
I made an iodine solution referring to the methodology provided in this link:
https://www.thoughtco.com/vitamin-c-determination-by-iodine-titration-606322
$$\ce{KIO3 + 5KI + 3H2SO4->3I2 + 3H2O + ...
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How is the molar weight of C-12 equal to 12 gram ? Why is "g" not considered while calculating molar weight? [closed]
So, I was just pretty confused about how we simply multiply the "mass" of total nucleons in Carbon by the Avogadro Constant, to get the molar "weight" as 12 grams, shouldn't it be ...
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what does it mean to say oxygen in a given context?
My textbook "chemistry by Julia" says the following
When it comes to expressing the molar mass of elements such as oxygen and hydrogen,
we have to be careful to specify what form of the ...
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will splitting a solution will keep the concentration values (and moles) the same? [closed]
I have this exercise from my H.W:
and I am asked: if we split the solution into 3 different containers equally -
how many moles will the solution have in each container?
will the Cl- concentration ...
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Will Avogadro's number change if definition of atomic mass unit is changed?
I know that the relation between atomic mass unit and Avogadro's number is a reciprocal relation.
My question is if the definition of atomic mass unit is changed, suppose instead of 1/12th mass of ...
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Mass percentage of limonene in a sample
I realize Chemistry Stack Exchange is not for homework and this will seem incredibly simple to many of you, but I have received no help elsewhere. I would really appreciate any support:
Limonene is ...
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Ratio of carbon monoxide and carbon dioxide when carbon and oxygen are made to react [duplicate]
$\pu{12 g}$ of $\ce{C}$ reacts with $\pu{64 g}$ of $\ce{O2}$ to give a mixture of $\ce{CO}$ and $\ce{CO2}$. Find amount of $\ce{CO}$ and $\ce{CO2}$ at the end of reaction.
What I tried was to let x ...
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Why is only mole fraction used in Henry's law and not some other measure of concentration?
Why is some other quantity like molality or molarity used?
I understand why mass percentage cannot be used as it is difficult to measure mass of gas...
Now is mole fraction used because solubility is ...
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Atoms vs molecule when talking about the avogadro's number? [duplicate]
By far, my understanding is that a molecule is made up of atoms bonded together. For example, a molecule of water ($\ce{H2O}$) has 2 hydrogen atoms and one oxygen atom.
However, when it comes to ...
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Using PV = nRT to solve an electrolysis problem
Question: Two electrolytic cells are connected in series (the same current passes through each cell). One cell for the electrolysis of water produces $\pu{100 cm^3}$
of oxygen, measured at $\pu{273 K}$...
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Confusion in solution for this Question regarding mole concept [closed]
$\pu{48g}$ of graphite and $\pu{16g}$ of $\ce{O2}$ is given. The question is to count the no of molecules of $\ce{CO2}$ produced?
Now, the solution in book is this
No of $\ce{C}$ atoms = $\frac{\pu{...
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Calculation of concentration at equilibrium for extraction
The equation for equilibrium of solvent-solvent extraction is:
$$\ce{PhOH(toluene) <=> PhOH (aq)}$$
An aqueous solution contain $\pu{1.5 \times 10^{-2} M}$ phenol and is shaken with the same ...
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Basis of mole concept? [closed]
We all have read that 1 mole of any substance contains $6.022 \times10^{23}$ atoms included in the substance. And:
$$Mole=\frac{weight}{molar\,\,mass}$$
Where molar mass is gram atomic mass such that ...
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Determine how much ethylacetate is formed from reaction equation
I have the reaction:
$$\ce{C2H5OH(l) + CH3COOH(l) <=> CH3COOC2H5(l) + H2O(l)}$$
and want to calculate how much ethylacetate is formed if I have $\pu{3 mol}$ of ethanol and $\pu{1 mol}$ of acetic ...
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Finding Gibbs energy at different temperatures just given Gibbs energy at one temperature
How would it be found the Gibbs energy at a certain temperature, if they just give you another Gibbs energy at a temperature? For example: Given $\Delta G = -230 Kcal/mol$ at $773K$ for the reaction $...
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How is this possible in mole concept? [closed]
L = $6.022*10^{23}$
If I have one atom of oxygen , it has exactly L value.
Now 2 atoms of a oxygen have 2L value.(Note that I mean 2O and not $O_2$here)
Well , if we take a molecule made up of 2atoms ...
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Mole Fraction and Atom Fraction [closed]
I'm probably overthinking this but would appreciate a peer check.
Mole fraction of element $i$ in compound: $\frac{\mathcal{M}_i}{\mathcal{M}}$
I used script M so as not to confuse with molar mass (...
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Filling up a table about a chemical reaction
I am filling up this table but I'm not sure about what it means in the mass row, amount of substance, molecule quantity.
In mass do I just have to repeat 16 in the second column or do I need to put ...
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Is this diagram correct for difference between 2N and N2
There is 1 $\ce{N2}$ molecule formed with 2 atoms of nitrogen.
2N is 2 separate nitrogen atoms which have not formed any bond.Reasons could be that they didn’t get enough energy to form bond so they ...
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Are the units of mole of oxygen molecules the same with the units of mole of nitrogen molecules?
Suppose we have in a box $3 \,{\rm mol}$ $\ce{O}$ and $3 \,{\rm mol}$ $\ce{N}$. Is the addition of these two quantities meaningfull? We do it all the time when we want to find the molar fraction. I ...
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Why does the Avogadro's number have the unit of reciprocal mole? [closed]
In my understanding,
$$1 \ mol \equiv N_A \ (atoms)$$
(Don't say it might not be atoms but molecules and also don't say what's it's not even a unit)
Then the unit should be $N_A = 1 \ mol/atoms = 1 \ ...
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A question about ligand binding
I have done part a and part b but I keep getting a negative concentration for part c.
For part a I got $\pu{2 \mu M}$
For part b I got $\pu{5.051 \mu M}$
For part c, I get $2=3.2 + \text{[bound ...
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What is the intuition behind 'mol' as a unit 'symbol'
Why are moles written with 'mol' as opposed to something which is easier to write with one character, or even two?
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Calculating the amount of moles from given number of atoms [closed]
Complete the sentences below by doing the mole calculations:
i)In $\pu{20 mol}$ of copper(II) phosphate, there are ______$\pu{mol}$ of copper ions and ______$\pu{mol}$ of oxygen atoms.
ii)A sample ...
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Preparing aqueous solution of ethanol [closed]
You need to prepare $\pu{250.0 mL}$ of an aqueous solution of ethanol in the concentration will be $\pu{0.500 mol L-1}$. You have $\pu{100 mL}$ of a commercial solution of ethanol in water $(35.0\% \,...
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When is Raoult's Law valid for solid-liquid solution?
Raoult's Law for solid-liquid solution is stated as such in my books that it is applicable for all non-volatile solutes.
However different solutes must have different attractive or repulsive forces ...
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Illustrating moles with sand grains, Are there more moles of SiO2 in a grain than moles of sand on the earth
I have been trying to understand the scale of atoms, thinking about sand grains as an example.
With approximately $7.5\times10^{18}$ grains of sand on the earth that is $1.25\times10^{-5}$ moles of ...
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Are moles of the solution equals to moles of the solvent + moles of the solute?
I'm a little bit confused here, does the mole of a solution equals to the mole of the solvent + mole of the solute?
Any help would be appreciated. Thank you.
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Confusing definition of mol when considering second order rate equations
I am confused by "$\text{mol}$".
I denote the unit of a physical quantity with square brackets (e.g. $[V]=l$), and the value of a physical quantitiy using curly brackets (e.g. $\left\{ V\...
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