# The mass of 14.25 times 10 to the twenty-fifth power of an inert gas molecule is 5kg. What kind of gas is it?

August 25, 2021 | education

| To determine a gas, we need to find its molar mass.

Let’s write an expression to determine the amount of a substance:

ν = m / M = N / Na, where m is the mass of the substance, M is the molar mass of the substance, N is the number of particles, Na is Avogadro’s constant Na = 6.023 * 10 ^ 23 1 / mol.

Let us express M from this expression:

M = m * Na / N

Substitute the numerical values:

M = m * Na / N = (5 * 6.03 * 10 ^ 23) / (14.25 * 10 ^ 25)) = 0.021 kg / mol.

According to the periodic table, we look at which substance has a molar mass of 0.021 kg / mol, in the table it is indicated in g / mol, we are looking for 21 g / mol, we find that it is Neon.

Answer: molar mass 0.021 kg / mol, this is Neon.