Question

Calculate the average atomic mass of lithium:

A) 6.94 amu
B) 6.98 amu
C) 7.02 amu
D) 7.06 amu

Answer 1

To calculate the average atomic mass of lithium, consider the isotopic composition of lithium-6 and lithium-7. Calculate the contribution of each isotope and add them to get the average atomic mass.

Step-by-step explanation:

To calculate the average atomic mass of lithium, we need to consider the isotopic composition of lithium. Lithium has two main isotopes: lithium-6 and lithium-7.

1. 
   
3. Calculate the contribution of each isotope:
4. 
   

• 
  
• Lithium-6: (0.0760)(6.015 amu) = 0.457 amu
• 
  
• Lithium-7: (0.9240)(7.016 amu) = 6.478 amu
• 
  

Add the contributions of each isotope to get the average atomic mass:

(0.457 amu) + (6.478 amu) = 6.935 amu