Is this the correct answer for question E3 in Fundamentals?

[MedhaVallurupalli1F]

Ans: 3.14 x 10^-21 g At

[Chem_Mod]

The question asks for the number of astatine atoms not the mass of astatine atoms. You need to compare the molar masses of gallium and astatine to determine how many astatine atoms the pan on the right would have to contain for the masses on the two pans to be equal. An atom of astatine is three times heavier than an atom of gallium. Therefore, if there are nine atoms of gallium on the left, there must be three atoms of astatine on the right for the masses on the two pans to be equal.

[KayleyW_3L]

Is the method of solving this question really as simple as seeing that (210 g/mol At) / (70 g/mol Ga) = 3, and therefore there must be 3 At atoms to balance out 9 Ga atoms since At is three times as massive as Ga ? Let's say the numbers were not as clean and involved decimals. Would the method of solving still be like this or would we need to use a different formula?

[Ryan Narisma 4G]

Hi KayleyW_3L! To answer your question, I think you would use the same method to determine how many atoms. In this problem, they used estimates for the molar masses just to model the difference in mass between the two different elements. I hope this helps!