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.

Filter by
Sorted by
Tagged with
2
votes
0answers
43 views

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 ...
-3
votes
1answer
43 views

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.
0
votes
1answer
21 views

Confusion defintion of mol when considering second order rate equations

I am a physicist and I am confused by "$\text{mol}$". I notate the unit of a physical quantity with square brackets (e.g. $[V]=l$), and the value of a physical quantitiy using curly brackets ...
1
vote
1answer
52 views

Mass percent and mole percent of a composition

The Problem A gas mixture contains hydrogen, carbon monoxide, and carbon dioxide. Calculate: a) The mass% hydrogen if the mixture contains 15 mol% $\ce{CO}$ and no $\ce{CO2}$; b) The molar composition ...
0
votes
1answer
26 views

Moles of chlorine gas needed to make up an equivalent amount of saturated salt solution

I’m trying to solve a question about a saturated salt solution but am unsure of how to answer one of the parts or what it’s asking for. The Problem The maximum solubility of table salt (NaCl) in water ...
1
vote
1answer
23 views

How did the temperature in the solution with a lower concentration of CuCl2 increased in a faster rate?

My lab assignment is about the reaction between $\ce{CuCl2}$ and Aluminium and we tracked the temperature of the solution every 15 seconds and we needed to make our own experiment to check how ...
1
vote
1answer
164 views

Confusion about Titration Formula [closed]

When performing a titration of a monoprotic acid and a monoprotic base, water can not be added to the titrant but water can be added to the analyte. To prove this statement to myself, I decided to ...
0
votes
0answers
28 views

Determining amount (in mols) of oxygen needed to fully combust coal

I'm trying to calculate the amount of oxygen needed to fully combust some coal. As an example, assume I have $\pu{1 kg}$ of coal which is, by mass fraction, 60% carbon ($\ce{C}$) 40% hydrogen ($\ce{...
-2
votes
2answers
72 views

How to calculate “volume of gas” generated by a given ion ore in a blast furnace? [closed]

A blast furnace makes pig iron containing $3.6\% \; \ce{C}$, $1.4\% \; \ce{Si}$, and $95\% \; \ce{Fe}$. The ore is $80\% \; \ce{Fe2O3}$, $12\% \; \ce{SiO2}$, and $\ce{Al2O3}$. The blast furnace gas ...
0
votes
1answer
38 views

What's the definition for mole before Avogadro's constant?

I have been searching for about 3 days how Avogadro's constant is found, and as all of us know the value is determined by division of charge of one mole of electrons (Faraday's constant) by the charge ...
20
votes
4answers
5k views

Why was Avogadro's number chosen to be the value that it is? [closed]

I understand that the mole is an extremely useful way of measuring and understanding atomic quantities. I did find some history of the number in its wikipedia article, but I did not find an answer to ...
1
vote
0answers
42 views

Question on chemical equilibrium [closed]

8 moles of so2 and 4 moles of O2 are mixed in a closed vessel.the reaction proceeds at constant temperature. By the moment when equilibrium sets in,80% of the initial amount of so2 enters into the ...
3
votes
1answer
58 views

How to deal with the unit “Coulomb per equivalent”? [duplicate]

In a question that I came across they defined $1\,\pu{F}$ as 96500 coulomb per equivalent. Now as far as my knowledge is concerned $1\,\pu{F} = 96500\,\pu{C/mol}$. The question involved asks to ...
1
vote
0answers
37 views

What is C2H33O28? (Empirical Formula to Molecular Formula) [closed]

I'm doing the final question on my homework, and got an issue with this question: "A 76.8g sample of a liquid used as a coolant in automobiles is found to contain 3.7 g of carbon, 5.1 g of hydrogen ...
0
votes
2answers
88 views

Determining a molecular formula of the catalyst for polymerisation of butadiene

I've got the following question in a workbook which I need to solve: A $\pu{50 g}$ sample of an experimental catalyst used in the polymerisation of butadiene is made up of $\pu{11.65 g}$ of $\ce{Co}...
-2
votes
1answer
57 views
5
votes
2answers
300 views

Why is molality per mass solvent rather than per mass of solution?

Knowing the moles of substance per mass of solution would be useful. Pour some solution and you'd know how much substance you have. Why is molality defined not this way, but as moles of substance per ...
1
vote
0answers
57 views

Determining heat capacity of gasses

I need a little help on answering a question which popped into my head while I was reading about gas laws: Suppose that I have three canisters, each holding a different gas of unknown identity [...
0
votes
1answer
31 views

What is the use of both mol and mass representing the same thing i.e. amount of something? [closed]

A mol is a unit but also has a magnitude. How can a unit have a magnitude? And if mole is used to measure an amount of substance than what does mass measure?
0
votes
1answer
264 views

How do I solve this problem on mass balance from blast furnace iron making?

Question An ironmaking blast furnace produces hot metal of the composition: $\pu{93.6\%}$ $\ce{Fe},$ $\pu{2.1\%}$ $\ce{Si},$ $\pu{3.6\%}$ $\ce{C},$ $\pu{0.7\%}$ $\ce{Mn}.$ The composition of the iron ...
0
votes
1answer
93 views

How to calculate the relationship between the pressures of zinc, carbon monoxide, and carbon dioxide based on mole balance?

Zinc oxide is reduced at a constant temperature in a closed reactor using $\ce{ZnO(s)}$ and $\ce{C(s)}$ as the only starting materials. The following reactions are assumed to be at thermodynamic ...
0
votes
1answer
755 views

How do I determine molality from mole fraction without knowing how much of the solution I have?

What is the value of $x$ if $x$ molal solution of a compound in benzene has a mole fraction of solute equal to 0.2? I tried calculating the moles of $x$ through the value given but there are two ...
1
vote
0answers
279 views

A tricky question in Eudiometry/Gas analysis

In a eudiometer $\pu{14 ml}$ of $\ce{CH4}$ and $\pu{38.5 ml}$ of $\ce{O2}$ was introduced. After explosion and cooling to initial temperature ($\pu{23°C}$) the volume of eudiometer was found to be $\...
-1
votes
1answer
77 views

Is molecular mass different than the molar mass? [duplicate]

I thought that molar mass is the mass of one mole of a substance whereas molecular mass is the mass of one molecule of a substance. But the molecular mass of water is 18.2 u, which is similar to its ...
-6
votes
2answers
176 views

Why is Avagadro's number independent of substance? [closed]

In the book of Irey, Thermodynamics, in vol1, IA, page 4, it is given that Molecular (atomic) weight $M$: The ratio of the mass of a molecule (atom) of a substance to one twelfth of the mass of an ...
0
votes
2answers
133 views

Identifying a chloride of the unknown element from the masses of chlorine and compound as well as vapor density [closed]

1 g of a chloride of an element contains 0.835 g of chlorine. If vapour density of the chloride is 85, find weight of the element and its valency. I tried to solve it but couldn't get to the answer ...
3
votes
1answer
207 views

Determining the charge on an ion through mole calculation in electrolyis

During electrolysis $\pu{0.02 mol}$ of metal $\ce{X}$ is deposited on cathode when $\pu{0.12 mol}$ of electrons are passed through molten chloride of $\ce{X}.$ What is the formula of the chloride? I ...
0
votes
1answer
241 views

Equivant mass of double salt

What is the equivalent mass of double salt like dolomite? And what if the double salt is hydrated? Is a double salt taken as a single unit while equating the gram equivalent in any reaction? For ...
0
votes
2answers
1k views

Finding the sum of coefficients of the reaction

What is the sum of the coefficients $(a + b + c)$ in the following reaction? $$\ce{x Zn + y HNO3} -> {a Zn(NO3)2 + b H2O + c NH4NO3}$$ Here if the equation is balanced we get 1 mol of $\ce{Zn}$ ...
-2
votes
3answers
122 views

Shouldn't the “law of conservation of mass” prevent equations from being unbalanced in the first place? [closed]

How is it that a chemical reaction produces an equation, that is essentially an impossibility, according to the law of conservation of mass? If the law is true, shouldn't all chemical reactions ...
2
votes
2answers
249 views

Molarity Numerical on Mixing Solutions

If 3 L of 1 M NaOH solution is prepared by mixing properties of stock solutions of $x$ L of 2.5 M NaOH and $y$ L of 0.4 M NaOH and no water is to be used, find $x : y$. My attempt: $$3 = 2.5x + 0.4y$...
0
votes
2answers
66 views

Determining amounts of product and excess reagent remaining post reaction

$$\ce{2FeS2 + 11/2 O2 -> Fe2O3 + 4 SO2}$$ Mass of $\ce{FeS2}$ is $\pu{600 g}$ and mass of $\ce{O2}$ is $\pu{800 g}$. Find the amounts of $\ce{Fe2O3}$ and $\ce{SO2}$ and the remaining amount of the ...
-2
votes
1answer
43 views

Help with question about mols in reactions

Consider the following reaction $$\ce{4H2O + 5I2O4 -> 8HIO3 + I2}$$ If 0.167 mol of $\ce{H2O}$ is added to 0.200 mol of $\ce{I2O4}$ what amount (moles) of $\ce{HIO3}$ can be formed, it the reaction ...
-3
votes
1answer
230 views

Determining the formula of tin(II) chloride hydrate [closed]

$\pu{1.20 g}$ of hydrated tin chloride decompose to form $\pu{1.01 g}$ of anhydrous tin chloride on heating. Calculate the value of $x$ given $$\ce{SnCl2.xH2O -> SnCl2 + x H2O}$$ I done it and ...
0
votes
0answers
15 views

Molecular weight of NiMnGaFe compund problem

I have a big problems calculating molar/molecular etc masses, because in my case I have a monocrystal, co I cannot imagine it as a molecule and my compound is made of Ni-Mn-Ga-Fe. I know the mass and ...
2
votes
0answers
45 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 ...
-2
votes
2answers
52 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....
22
votes
1answer
3k views

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 ...
-1
votes
3answers
1k views

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 ...
12
votes
4answers
1k views

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/...
-1
votes
1answer
2k 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 ...
0
votes
1answer
336 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 ...
-2
votes
1answer
47 views

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

I have tried to look it up, and find answers, it really intrigues me!
0
votes
1answer
63 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 ...
-1
votes
1answer
58 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: ...
4
votes
1answer
99 views

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

Avogadro's constant $N_\mathrm A$ 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 ...
-3
votes
1answer
66 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 ...
-2
votes
3answers
86 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?
0
votes
1answer
95 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 ...
-1
votes
1answer
45 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 ...

1
2 3 4 5