Average Atomic Mass HW

Honors Chem

Complete the following problems. Show all work on a separate sheet of paper.

Average atomic mass =Σ(mass of isotope× relative abundance in decimal form)

Find the average atomic mass of each of the following elements given the info in the tables below:

mass number / exact weight / percent abundance
24 / 23.985042 / 78.99
25 / 24.985837 / 10.00
26 / 25.982593 / 11.01
  1. a. Siliconb. Magnesium

mass number / exact weight / percent abundance
28 / 27.976927 / 92.23
29 / 28.976495 / 4.67
30 / 29.973770 / 3.10
  1. If element X consists of 78.7% of atoms with a mass of 24.0 amu, 10.1% of atoms with a mass of 25.0 amu and 11.2% of atoms with a mass of 26.0 amu what is the average atomic mass of element X?
  1. What is the average atomic mass of element Y if Y consists of 57.25% of atoms with a mass of 120.90 amu and 42.75% of atoms with a mass of 122.90 amu?
  1. Naturally occurring chlorine that is put in pools is 75.53% chlorine-35 (mass = 34.969 amu) and 24.47% chlorine-37 (mass = 36.966 amu). What is the average atomic mass of Cl? Does it match up with what is on the periodic table?
  1. Boron has an atomic mass of 10.81 amu according to the periodic table. However, no single atom of boron has a mass of 10.81 amu. How can you explain this difference?

Average Atomic Mass HW

Honors Chem

Complete the following problems. Show all work on a separate sheet of paper.

Average atomic mass =Σ(mass of isotope× relative abundance in decimal form)

Find the average atomic mass of each of the following elements given the info in the tables below:

mass number / exact weight / percent abundance
24 / 23.985042 / 78.99
25 / 24.985837 / 10.00
26 / 25.982593 / 11.01
  1. a. Siliconb. Magnesium

mass number / exact weight / percent abundance
28 / 27.976927 / 92.23
29 / 28.976495 / 4.67
30 / 29.973770 / 3.10
  1. If element X consists of 78.7% of atoms with a mass of 24.0 amu, 10.1% of atoms with a mass of 25.0 amu and 11.2% of atoms with a mass of 26.0 amu what is the average atomic mass of element X?
  1. What is the average atomic mass of element Y if Y consists of 57.25% of atoms with a mass of 120.90 amu and 42.75% of atoms with a mass of 122.90 amu?
  1. Naturally occurring chlorine that is put in pools is 75.53% chlorine-35 (mass = 34.969 amu) and 24.47% chlorine-37 (mass = 36.966 amu). What is the average atomic mass of Cl? Does it match up with what is on the periodic table?
  1. Boron has an atomic mass of 10.81 amu according to the periodic table. However, no single atom of boron has a mass of 10.81 amu. How can you explain this difference?