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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1 mole of substance is equal to atomic/molecular mass in grams?

I have been reading the answer of this question here- Why is weight of 1 mole of substance equal to atomic/molecular mass in grams I feel that the answer writer was wrong to say that -"the ratio of g/...
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finding molar mass of a molecule [closed]

Why is the molar mass of a molecule defined as the the sum of molar mass of all the atoms present in the molecule? For example, suppose we have to calculate the molar mass of $\ce{H_2O} $ molecule. ...
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units of mole formula [closed]

I am a high school student.I am currently studying "moles" chapter in my textbook.I think my book is misleading me in regards with units of a formula. The formula is, NO.of moles= (Given mass of an ...
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Why is the mass of 1 mole of an atom/molecule equal to its gram atomic/molecular mass?(proof) [duplicate]

Why do we take the mass of 1 mole of an atom to be equal to its gram atomic mass and the mass of 1 molecule to be equal to its gram molecular mass? I want a mathematical rigorous proof. There are ...
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Equivalent weight of calcium phosphate

In a reaction, calcium phosphate is producing calcium hydrogen phosphate. Then we have to find the equivalent weight of calcium phosphate in this process. I tried as: Oxidation number of calcium ...
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Stoichiometry and POAC Contradiction

Lets say we have the reaction $$\ce{H2 + O2 -> H2O}$$ And we are given 10 moles of $\ce{O2}$ and are asked that How many moles of hydrogen gas do we need to complete the reaction ? ...
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What does mol L−1 mean? [closed]

I am researching how to Determination of Vitamin C Concentration by Titration for my science fair project and it says Titrate the sample with $0.005~\mathrm{mol~L^{−1}}$ iodine solution. The ...
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What is a mole?

Is my understanding of the concept of a mole correct? The mole is a simply a number ($6.023 \times 10^{23}$). It's just like what a dozen would be like for eggs, except that the mole applies to atoms ...
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Why does Avogadro's number have the value it has? [duplicate]

As I was learning about Avogadro's number and I was wondering why is Avogadro's number equal to $6.02214\cdot 10^{23}$? I mean, how did chemists come up with this particular number?
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How to correctly write “7 apples” according to the international system of units (SI)

According to international system of units (SI), we can write "7 kg of apples" to refer to the mass of these apples. However, if we want refer to the amount of apples, that is, the number of ...
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Effects of Changing Avogadro's Constant

The Avogadro project suggests that we redefine the Avogadro constant to be equal to our best known estimate, $N_\mathrm{A} = 6.02214179 \times 10^{23}$, and redefine the kilogram based on the Avogadro ...
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What exactly is a mole?

Upon coming back to University I've started studying basic chemistry again. I've always had trouble with the concept of "moles". According to my study book, 1 mole of any element or compound is ...
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Why is molar mass the same as atomic mass? [duplicate]

I am completely confused about why molar mass is the same as atomic mass. Could someone help explain why, thoroughly, but in simplified terms?
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Avogadro's number and percent error help?

Calculate the percent error in Avogadro’s number calculated by using the following experimental data. Pipette calibrated as 30 drops/mL Diameter of the watch glass: $15.5\ \mathrm{cm}$ Number of ...
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Why does a certain number of moles of gas occupy a set volume?

In class, I was taught that 1 mole of an ideal gas occupies a set volume eg 22.4 L at STP. Why does the gas only occupy a certain volume and not just keep expanding forever, having limitless volume? ...
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Pepto-bismol molar bismuth concentration

I want to measure the Bismuth molar concentration in the OTC drug "pepto bismol". 525 mg bismuth subsalicylate (C7H6BiO4) / 30 mL (17.5 mg/mL) molecular weight 363.10054 g/mol If I convert to mM (17....
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To find the value of x in a metal chloride MClx [closed]

A solution containing 0.1 mol of a metal chloride MClx requires 500 ml of 0.8 M AgNO3 solution for complete precipitation. The value of x is: (a) 1 (b) 2 (c) 4 (d) 3 Please answer with an ...
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How to calculate the number of atoms of each element in a urea?

I have a stoichiometry question which I answered incorrectly and I am not sure where I went wrong. The question is as follows: Urea, $\ce{(NH2)2CO}$, is used for fertilizer and many other things. ...
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How to calculate the amount of substances product produces from the masses and amounts of starting materials?

Calculate the amount of carbon dioxide formed when we burn 1 mole of carbon in the presence of 16 g of dioxygen. $$\ce{C + O2 -> CO2}$$ 1 mole of carbon means 12 g. Therefore amount of ...
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How does 1 mole of a compound = the molecular weight of the compound?

I am reviewing moles, and came across this sentence in my book: One mole of a compound has a mass in grams equal the molecular weight of the compound expressed in amu and contains $6.022\times10^{...
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How to make by dilution a certain ion concentration

The question I'm trying to answer is this: What volume of $0.25\ \mathrm{mol/l}$ calcium nitrate is required to make by dilution with water $500\ \mathrm{cm^3}$ of a solution with a nitrate ion ...
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How is H2 2 moles [duplicate]

I saw a question that asked which expression can be used to designate 2 moles of atoms. The choices were H2 C02 2N20 2NaCl H2SO4 The answer is H2 but I was confused because I thought H2 is only 1 ...
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Does 12 amu really equal the mass of one carbon-12 atom? [duplicate]

As I was studying chemistry, I encountered atomic mass units (amu) and based on some calculations, I realized that some numbers don't work out. Apparently, 12 amu is the mass of a single carbon-12 ...
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How many moles of sodium are there in 10mls of 30% sodium chloride?

How many moles of sodium are there in 10mls of 30% sodium chloride? 30% of 10mls is 3g NaCL. There is 3000mg of NaCl and would that be divided by the molecular weight of NaCl or of just Na? I ...
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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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Why is Avogadro's statement true that at STP conditions all matter have same number of atoms or molecules?

As atomic number increases, atomic size, number of electrons and shells also increase. So due to higher atomic size and maximum number of electrons, there should be maximum repulsion forces between ...
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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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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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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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954 views

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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How to calculate the mass of a single atom?

If we know the molar mass of a certain element and Avogadro's constant, how can we calculate the mass of a single atom? Do we need to multiply the molar mass with 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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759 views

How to calculate a molar mass based on density?

I have been asked to calculate the molar mass and mole fraction of a 35 w/w% HClO4 solution with a density of 1.3g per ml. This is the equation I used to try to solve it: $\frac{1}{M} = \frac{0.35}{...
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Is this definition of mole correct?

Chemical engineers define one mole as the amount of a substance which possess as many entities as $12\ \mathrm g$ of $\ce{^{12}C}$. The number of atoms in $12\ \mathrm g$ of $\ce{^{12}C}$ is $6.022 \...
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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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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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Molarity of Sodium Ion Concentration (and some really weird answers…)

I know how to do this problem really easily but I don't know why my answer is wrong... The problem is: What is the molarity of sodium ions in a solution prepared by diluting $250\ \text{mL}$ of $0....
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How do I calculate the cost of a single Aluminum atom?

I am doing a Chemistry assignment in which I was given a piece of aluminum foil which I had to measure and use for my calculations. I am supposed to calculate the cost of a single aluminum atom using ...