Question

A sample of chlorine has two naturally occurring isotopes. The isotope Cl-35 (mass 35.0 amu) makes up 75.8% of the sample, and the isotope Cl-37 (mass = 37.0 amu) makes up 24.3% of the sample. What is the average atomic mass for chlorine?

A. 36.0 amu
B. 35.521 amu
C. 35 amu
D. 36.6 amu
E. 35.5 amu

Answer 1

The average atomic mass for chlorine is 35.52 amu.

Step-by-step explanation:

The average atomic mass for chlorine can be calculated by multiplying the mass of each isotope by its abundance and then summing the results. In this case, we have 75.8% of Cl-35 with a mass of 35.0 amu, and 24.3% of Cl-37 with a mass of 37.0 amu.

To calculate the average atomic mass, we multiply 75.8% by 35.0 amu, and 24.3% by 37.0 amu:

(0.758 x 35.0) + (0.243 x 37.0) = 26.53 + 8.99 = 35.52 amu

Therefore, the average atomic mass for chlorine is 35.52 amu.