Question

If $22.4L$ of hydrogen gas contains how many molecules?

Answer 1

As we know that the molecule of hydrogen has two atoms of hydrogen as it is a diatomic molecule because it is found in the form of pairs. So we know by mole concept that two moles of the hydrogen contains 1 mole of hydrogen or 22.4 L of hydrogen. The one mole or the $22.4L$ of substance is equal to the Avogadro number. So now we can calculate the number of molecules in 22.4L.

Complete step-by-step answer:
So as we know that hydrogen being a diatomic molecule has the atomic number 1 and the atomic weight of 1. So if we talk according to mole concept we know that 1 mole of the atom is equal to the 22.4 L of that element. Now we can also say that the 1 mole is equal to the Avogadro number which is $6.023 \times {10^{23}}$ molecules.

So for hydrogen $22.4L$ of hydrogen has = $6.023 \times {10^{23}}$ molecules as it is = 1mole of hydrogen. So the number of molecules contained in $22.4L$ of the hydrogen is $6.023 \times {10^{23}}$ molecules. The 1 mole of the element is not certainly equal to one gram for all the elements as it depends on their existence. So for hydrogen we have seen that 1 mole here is equal to 2 grams but for helium 1 mole would be equal to 1g. And in the question a standard volume was given to us for finding the molecules so it was easy but if suppose 21.5 L would have been given then we have multiplied the 21.5L with the Avogadro number.

Note: Avogadro number is the number of the units which is present in 1 mole of the substance. It is defined as the proportionality factor. It helps in relating the amount of the constituent particles present in the sample with the amount of the substance of the sample given.