Sunday, March 31, 2013

Calculate the mass of 6.022 × 10^25 atoms of oxygen. Is it 1600?

Hello!


Actually, you are right. `6.022*10^23` is the Avogadro number, the number of particles in one mole of a substance. In our case particles are atoms of oxygen. It is also known that one mole of a substance has a mass of as many grams as the atomic mass of its particle.


The atomic mass of oxygen is 16 amu (it is measured in 1/12 of the mass of a carbon-12 atom). Also, the given number of atoms, `6.022*10^25,` is 100 times greater than the Avogadro number. So the mass of this quantity of atoms is 16 g*100 = 1600 g = 1.6 kg.


That said, oxygen has three different stable isotopes: oxygen-16 (the most common), oxygen-17 and oxygen-18. They are found in nature, so choosing carefully, one can collect 1.7 or 1.8 kg of this quantity of oxygen atoms:)

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