Question

What is the atomic mass of hafnium if, out of every 100 atoms, 5 have a mass of 176 amu, 19 have a mass of 177 amu, 27 have a mass of 178 amu, 14 have a mass of 179 amu, and 35 have a mass of 180.0 amu?

a) 177.04 amu
b) 178.15 amu
c) 179.08 amu
d) 180.00 amu

Answer 1

The atomic mass of hafnium is 178.15 amu

Step-by-step explanation:

The atomic mass of hafnium can be calculated by multiplying the mass of each isotope by its relative abundance and then summing up the results. In this case, out of every 100 hafnium atoms, 5 have a mass of 176 amu, 19 have a mass of 177 amu, 27 have a mass of 178 amu, 14 have a mass of 179 amu, and 35 have a mass of 180.0 amu. We can calculate the average atomic mass by multiplying the mass of each isotope by its relative abundance:

(5 * 176) + (19 * 177) + (27 * 178) + (14 * 179) + (35 * 180.0) = 17815

Then, we divide the sum by 100 to get the average atomic mass:

17815 / 100 = 178.15 amu

Therefore, the atomic mass of hafnium is 178.15 amu.