# 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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### Calculating the molartity of DNA in a cell

In the following questions use a value of 3 for $\pi$, $6 \times 10^{23}$ for Avogadro’s number and 660 for the molecular weight of 1 bp of DNA. The volume of a sphere of radius r is $4/3\,πr^3$. ...
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### Equilibrium constant calculation from concentrations

Consider the following equilibrium: $\ce{A2\ _{(g)} + 2B_{(g)} <=> 2AB_{(g)}}$ A chemist puts 8.0 moles of $\ce{A2}$ and 10.0 moles of $\ce{B}$ into an evacuated 1.0 L container. The system ...
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### ions proportion [closed]

I have a precipitation reaction of this form: $\ce{Ca^{2+} + CO_{3}^{2-} → CaCO3}$ How many mole of $\ce{Ca^{2+}}$ ion is contained in a 200ml solution? I'd like to know how to calculate this, ...
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### Calculating percentage composition after drying

A partially dried clay mineral contains 8% water. The original sample contains nearly 12% water and 45% silica. The percentage of silica in the partially dried sample is nearly 50% 49% 55% 47% I ...
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### Mass of a gas sample

What method did John Dalton use to measure the mass of one mole of gases, for example, chlorine and hydrogen, to get their relative masses?
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### Why do people still use the mole (unit) in chemistry?

I know that the mole is widely used in chemistry instead of units of mass or volume as a convenient way to express amounts of reactants or of products of chemical reactions. I'm wondering why people ...
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### Copper oxidation

In an experiment we conducted, we heated 1.6 grams of copper dust, and got 1.7 grams of oxidised copper, (it probably reacted with 0.1 grams of $\ce{O2}$) and our goal was to find which of the two ...
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### Why is the mole a unit of measurement?

I really can't understand why is the mole a unit of measurement and not just a constant. I mean, we use units to express things that we can measure but that are not countable, that are continuous - ...
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### I have to write a Python program relating with molecular weight. Any insight?

Write a program that determines the molecular weight of a chemical compound based on the number of hydrogen, carbon, and oxygen atoms in the compound. You should use the following atomic weights: \...
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### Are my calculations correct for this reaction?

So in the reaction $\ce{2AgNO3 + Cu -> 2Ag + Cu(NO3)2}$, which is balanced, I was given $0.1\text{ g}$ of $\ce{Cu}$ that reacted. Are my calculations correct that if $0.1\text{ g}$ of $\ce{Cu}$ ...