# 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-...

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### Why are osmoles not considered SI units?

The Wikipedia article for osmoles is pretty clear on what they are and how they are used. Right off the bat, though, it states that the osmole is not an SI unit, and indeed the usual lists of derived ...
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### Why convert to moles for stoichiometry calculations? [closed]

Why do you have to convert the reactants and products of an equation to moles when doing stoichiometry problems? Why can't you just convert straight to grams to solve the problem?
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### How to determine the equation for the reaction of europium with sulfuric acid based on experimental measurements?

I was given a set of results by a fellow researcher where he reacted $0.608~\mathrm{g}$ of europium ($M = 152$) with an excess of $\ce{H2SO4}$ and collected $144~\mathrm{cm^3}$ of $\ce{H2}$ gas at ...
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### Volume of one equivalent of a gas

How do we define an equivalent when we are not talking about any particular reaction? Like, we say that equivalent volume of Oxygen is 5.6L, so we have taken the n-factor to be 4, and in CO2 we take n-...
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### Calculating molar mass from gas data

34.05 mL of phosphorus vapour weighs 0.0625 g at 546 °C and 0.1 bar pressure. What is the molar mass of phosphorus? I tried to solve the above question and got 1249.8g. The book's answer sheet lists ...
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### How many mL of 10.00 M HCl are needed to make up 80.0 mL of 0.175 M HCl?

I've tried this multiple times, but I don't know how to set the problem up when it gives you both molarities. If someone could show me how to set up this problem please!? I think it has something to ...
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### Find the amount of atoms for a given mass

The atomic mass of two elements A and B is 40 and 80 respectively. If x g of A contains y atoms, how many atoms are present in 2x g of B? I have tried to solve by assuming that x g of A has y atoms ...
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### How to calculate n factor for redox reactions? [duplicate]

Books generally don't go deep into this concept but i need to know,how to calculate the n factor for various types of redox reactions like oxidation number of one element changes and goes into 2 ...
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### Why do we assume that it is 1 mol?

A question in my book was as following: Benzine and chloroform are considered very toxic organic solvents that dissolve in each other and in a solution of benzine and chloroform there is 0.45 mol ...
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### Number of water molecules to contribute one molecule to every milliliter on earth

How many millilitres of water would it take so that, when they are thoroughly dispersed around the world, it would yield an average of one molecule of the original sample of water in each millilitre ...
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### Raoult's Law and Mole Fraction

Raoult's Law states that the partial vapor pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture....
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### Calculating the mass of a single atom

If we know the molar mass of a certain element and the Avogadro's constant, how can we calculate the mass of a single atom? Do we need to multiply the molar mass value and Avogadro's constant?
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### How to calculate the maximum number of molecules or ions from a given amount of substance?

Which of the following solutions has the greatest number of particles (atoms or ions) of solute per liter? (a) $1~\mathrm{M}\ \ce{NaCl}$ (b) $1~\mathrm{M}\ \ce{CaCl2}$ (c) $1~\mathrm{M}$ ...
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### Calculate the heat of a reaction

Say I would like to calculate the heat produced by the following reaction: $$\ce{2SO2 + O2\longrightarrow2SO3}$$ I have calculated the moles of the reagents. I can't seem to figure out how to ...
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### Determining water of crystallisation in a hydrate from the mass percentages

How would I find the amount of water in a hydrate if all I was given was the mass percentage of one element in the compound? For example, a question asks: $\ce{Zn(ClO3)2.$x$H2O}$ contains $21.5\%$ ...
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### Ratios and mass; reaction calculation problem

I have come across the following problem: One method used to inflate air bags in cars is to use nitrogen produced chemically from the decomposition of sodium azide. The sodium formed reacts with ...
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### What's the empirical formula of this solid? Reacting mass calculation

I have come across the following problem: $1.00\ \mathrm g$ of sulphur dissolved completely in an excess of liquid ammonia to give $420\ \mathrm{cm^3}$ of hydrogen sulphide ($\ce{H2S}$), measured ...
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### pH of a mixture of base and an acid

I have the following question: Assume that you have two solutions. One of $50\ \mathrm{cm^3}$ $\ce{HCl}$ $\mathrm{pH} = 1.3$ and one of $150\ \mathrm{cm^3}$ $\ce{Ba(OH)2}$ $\mathrm{pH} = 12.3$. If we ...
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### How many grams of sodium sulfate and water in 100ml of 0.5M solution

Calculate how many grams of sodium sulfate ($\ce{Na2SO4}$) and water ($\ce{H2O}$) should be used to prepare $\pu{370 g}$ of 15% solution of this salt. How many mL of this 15% solution should be taken ...
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### Can chemicals be identified by their molar mass?

Wouldn't it be possible to identify a chemical by measuring its molar mass? How much accuracy does the measured molar mass need to be to guess what chemical it could be? EDIT: @ortho makes an ...
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### How to Find the Mass of an Individual Element in a Compound/Molecule [closed]

What is the procedure/math for finding the mass of a specific element in a substance? For instance, how many grams of Oxygen are in 6.8 grams of Epinephrine (Adrenaline)?
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### Can anyone give me detailed logical solution to my questions? [closed]

What is 1 amu? From where it is derived? Why it is compared with carbon-12? Why it was once compared with hydrogen-1? and now its not? Can anyone please explain me logically? And what would have ...
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### How is the mol highway used in this problem?

How many moles of propane gas, $\ce{C3H8}$, are contained in 11 grams of the gas at standard conditions? Also, can you please explain step-by-step (and include sigfigs?) I think I might know how to ...
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### How to find the number of hydrogen atoms in 0.5 mol of hydrogen gas?

How do I calculate the number of hydrogen atoms in $\pu{0.5 mol}$ of hydrogen gas? I presume the answer would probably somehow use the equation $$n = \frac{m}{M},$$ where $n$ is the amount of ...
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Here's something that makes me confuse. What will happen to the total no of moles in a system if the temp is raised. Will it increase? If so how is that possible.? Say we have an equlibrium, \ce{2P &... 2answers 23k views ### Converting g/L to mol/L I know I should divide \mathrm{g~L^{-1}} by the molar mass of the substance, but I don't seem to find the specific answer on Google. So just to be sure: If I have 10^{-5}~\mathrm{g~L^{-1}}~\ce{Cu^... 1answer 46k views ### What is the mass of 1 atom of carbon? I know that relative atomic mass of \ce{^{12}C} is 12~\mathrm{u}. Therefore mass of 1~\mathrm{mol}~\ce{C} = 12~\mathrm{g} \begin{align} \text{mass of }6.022\cdot 10^{23} \text{ C atoms} &= ... 0answers 243 views ### Co49Ni21Ga30 - molar mass and density I need to calculate the molar mass and density of the shape memory alloy \ce{Co49Ni21Ga30} (I suppose the numbers indicate the mass percentage). To get the molar mass, is it correct to use the ... 2answers 4k views ### How much sulphuric acid can be obtained from 5 kg of sulfur How much sulfuric acid (\ce{H2SO4}) can be obtained from 5 kg of sulfur \ce{S8}? answer: 15.312 kg To make 1 molecules of \ce{H2SO4} we need 1 atoms of S. Now coming to \ce{S8}. ... 1answer 7k views ### Do I have to consider the molecular mass of the oxygen atom or the diatomic oxygen molecule when determining the empirical formula of an iron oxide? In determining the empirical formula of a compound which constitutes a diatomic molecule, should we calculate the molar mass of the divalent molecule by multiplying the molar mass of the element by 2, ... 1answer 3k views ### How to calculate the osmotic pressure of a sucrose solution? The boiling point of an aqueous solution containing sucrose, \ce{C12H22O11}, is 101.45~^\circ\mathrm{C}. Calculate the osmotic pressure of this solution at 35~^\circ\mathrm{C}, at which the ... 1answer 25k views ### How to calculate valence factor (n-factor) for a element? Suppose I am given some reaction in which\ce{C6H12O6 -> CO2}$$and I want to calculate n-factor for this reaction to ultimately calculate equivalent weight of carbon for this reaction. Since$$...
The ultimate analysis (by weight percent) for beech wood is: $$\ce{C}=49.05\,\%,\; \ce{H}=5.83\,\%,\; \ce{O}=45\,\%,\; \ce{N}=0.12\,\%$$ Using the ultimate analysis values, the molar mass of each ...