Fundamentals E.3

[alexia11]

I am reviewing past syllabus questions in preparation for the final. The question asks how many astatine atoms would be needed to have equal mass. If we are just given the molar masses how do we calculate the number of atoms needed for the two pans to be equal?

[Ayush Patel 3G]

If you are given that the mass of one sample of element is g grams and need to find the number of atoms of another element required for a sample of the same mass, you just need to take the mass of the sample and divide it by the molar mass of the second element, then multiply by Avogadro's number.

[Miguel Hernandez LEC 3]

For this question based on the given figure, you would need 3 astatine atoms in order for the atoms to have equal mass. When you are given only the molar masses, you would set up the expression. moles of gallium * molar mass of gallium = moles of astatine * molar mass of astatine. You would then plug in the molar masses described in the question and then rearrange the equality to find the ratio of moles of gallium to moles of astatine. With this you get 70/210 or 1/3. Therefore there should be 1/3 the amount of astatine to gallium for them to be equal in molar mass.