# 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.

211 questions
Filter by
Sorted by
Tagged with
18 views

### How to determine the concentration of the acid solution by titration? [closed]

A student determined the concentration of a hydrochloric acid solution by titration with $\pu{25.0 cm3}$ portions of a $\pu{0.05 M}$ primary standard solution of anhydrous sodium carbonate. The ...
52 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 [...
29 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?
110 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 ...
82 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 ...
229 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 ...
110 views

98 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 ...
193 views

135 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 ...
89 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 ...
47 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. ...
82 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 ...
343 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 ...
209 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 ...
28 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 ...
141 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 ...
949 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 ...
1k 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 ...
919 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 ...
2k 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 ...
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 ...