Question

question 3 (1.666666667 points)
there are two stable isotopes of gallium, $^{69}$ga and $^{71}$ga. calculate the average atomic mass from the following data from the mass spectrometer.
isotope % abundance relative mass mass contribution
ga - 69 60.1089 68.925580 amu
ga - 71 39.8929 70.924701 amu
what is the mass contribution for ga - 69?
4143.0408
41.430408
41.430408 amu
4143.0408 amu

Explanation:

Step1: Recall mass - contribution formula

The mass - contribution of an isotope is calculated by multiplying its percentage abundance (in decimal form) by its relative mass. First, convert the percentage abundance of Ga - 69 to a decimal. The percentage abundance of Ga - 69 is 60.1089%, so in decimal form it is $60.1089\div100 = 0.601089$.

Step2: Calculate mass - contribution

Multiply the decimal - form of the percentage abundance by the relative mass of Ga - 69. The relative mass of Ga - 69 is 68.925580 amu. So the mass - contribution is $0.601089\times68.925580\approx41.430408$ amu.

Answer:

41.430408 amu