Calculating Isotopic Abundance

In this video, Madame Wash explains how to calculate the percentage abundance of isotopes using mass spectrum data and average atomic mass values. The video covers two examples: the mass spectrum of iridium and the relative atomic mass of boron. For iridium, the video demonstrates calculating the percentage abundance of isotopes using their relative abundance. For boron, it shows how to use the average atomic mass to find the percentage abundance of its isotopes. The video concludes with a summary of the calculations and results.

What is the main topic discussed in the video?

• Learning about the periodic table

• Understanding chemical reactions

• Studying molecular structures

• Calculating percentage abundance from mass spectrum

How do you calculate the percentage abundance of an isotope using its relative abundance?

• Add its relative abundance to the total relative abundance

• Multiply its relative abundance by the total relative abundance

• Subtract its relative abundance from 100

• Divide its relative abundance by the total relative abundance and multiply by 100

What is the percentage abundance of iridium-191 if its relative abundance is 5.0?

• 38%

• 25%

• 50%

• 62%

What is the alternative method for calculating the percentage abundance of the second isotope when only two isotopes are present?

• Subtract the percentage abundance of the first isotope from 100%

• Divide the percentage abundance of the first isotope by 2

• Add the percentage abundance of the first isotope to 100%

• Multiply the percentage abundance of the first isotope by 2

What is the relative atomic mass of boron used in the second question?

• 10.8

• 11.0

• 10.0

• 12.0

If boron-10 has an isotopic mass of 10, what is the assumed percentage abundance of boron-10?

• x

• y

• w

• z

What is the formula used to calculate the average atomic mass?

• Summation of k me minus summation of key

• Summation of k me plus summation of key

• Summation of k me times summation of key

• Summation of k me over summation of key

What is the percentage abundance of boron-11 if boron-10 is 20%?

• 80%

• 60%

• 50%

• 20%

What is the isotopic mass of boron-11 used in the calculation?

• 9

• 12

• 10

• 11

What is the final step in concluding the percentage abundance calculation for boron isotopes?

• State the percentage abundance of each isotope

• Recalculate the isotopic masses

• Subtract the isotopic masses

• Add the isotopic masses