The molar mass of HCl is 36.5 g/mol, and the average mass per HCl molecule is 36.5 u. Use the fact that 1 u = 1.6605 * 102 24g to calculate Avogadro's number.

Video transcript

All right. Hi, everyone. So this question says that the molar mass of HCL is 36.5 g per mole. And the average mass per HCL molecule is 36.5 units or atomic mass units use the fact that one unit is equal to 1.6605 multiplied by 10 to the negative 24th grams to calculate Avogadro's number. And here we have different answer choices labeled A through D proposing different values. Now recall first and foremost that Avogadro's number discusses the relationship or gives a quantity as to the number of entities per mole of a substance. Now, the word entities can be atoms, molecules, particles, ions, etc depending on the context of the problem. But because HCL is a molecule, we're going to be discussing molecules per mole for this question just to be more specific. Now, because our target units are molecules per mo we're going to have to divide grams per mole by the amount of grams per molecule. This ensures that units of grams cancel out and we're left with our target unit molecules per mole. Now, in this case, we were given the mass per HCO molecule in atomic mass units. So first, we're going to convert this into units of grams per molecule. So that's 36.5 atomic mass units modified by 1.6605 multiplied by 10 to the power of negative 24 grams per one atomic mass unit. This ensures that atomic mass units cancel out and the product is equal to 6.06 0825 multiplied by 10 to the power of negative 23 grams per molecule. So now we have the information necessary to find Avogadro's number. So Ava Ghos number is equal to the molar mass of HCL. That's 36.5 g per mole divided by the mass of one HCL molecule in grams. So that's 6.060825 multiplied by 10 to the power of negative 23 grams per molecule of HC. So after evaluating this quotient and rounding to three significant figures or answer for avocado's number is equal to 6.02 multiplied by 10 to the 23rd power molecules per mole of HCL. And this corresponds to option C in the multiple choice and there you have it. So with that being said, thank you so very much for watching. And I hope you found this helpful.