Isotope Calculation Questions (Answer Key)

University:
San Jose State University
Course:
CHEM 10 | Chemical Calculations and Concepts
Academic year:

2022
Views:

373

Pages:

2
Author:

Killian Mata

1) Average Atomic Mass = Mass1 ×%1 + Mass 2 ×% 2 69.72 amu = 68.926 amu i X + 70.9247 amu i (1 - X) 69.72 amu = 68.926 amu i X + 70.9247 amu - 70.9247 amu i X 69.72 amu = −1.9987 amu i X + 70.9247 amu −1.2047 amu = −1.9987 amu i X 0.6027 = X ⇒ 69 Ga = 60.27% 1 - 0.6027 = 0.3973 ⇒ 71 Ga = 39.73% 2) Average Atomic Mass = Mass1 ×%1 + Mass 2 ×% 2 107.870 amu = 106.905 amu i X + 108.9048 amu i (1 - X) 107.870 amu = 106.905 amu i X + 108.9048 amu - 108.9048 amu i X 107.870 amu = −1.9998 amu i X + 108.9048 amu −1.0348amu = −1.9998amu i X 0.5175 = X ⇒ 107 Ag = 51.75% 1 - 0.5175 = 0.4825 ⇒ 109 Ag = 48.25% 3) Average Atomic Mass = Mass1 ×%1 + Mass 2 ×% 2 6.939 amu = 6.015 amu i X + 7.016 amu i (1 - X) 6.939 amu = 6.015 amu i X + 7.016 amu - 7.016 amu i X 6.939 amu = −1.001 amu i X + 7.016 amu −0.077 amu = −1.001amu i X 0.077 = X ⇒ 107 Ag = 7.7% 1 - 0.077 = 0.923 ⇒ 109 Ag = 92.3% 4) Average Atomic Mass = Mass1 ×%1 + Mass 2 ×% 2 85.47 amu = 84.912 amu i 0.7217 + X i(1 − 0.7217) 85.47 amu = 84.912 amu × 0.7217 + X i0.2783 85.47 amu = 61.281 amu + 0.2783i X 24.189 amu = 0.2783X 86.92 amu = X 87 5) Rb = 86.92 amu Average Atomic Mass = Mass1 ×%1 + Mass 2 ×% 2 + Mass 3 ×% 3 + Mass 4 ×% 4 Average Atomic Mass = 49.946amu×0.0435 + 51.941amu×0.8379 + 52.941amu×0.0950 + 53.939amu×0.0236 Average Atomic Mass = 2.17265amu + 43.52136amu + 5.02940amu + 1.27296amu Average Atomic Mass = 51.996amu 6) Average Atomic Mass = Mass1 ×%1 + Mass 2 ×% 2 + Mass 3 ×% 3 + Mass 4 ×% 4 87.62amu = 83.91amu×0.0056 + 85.909amu×0.0986 + 86.9909amu×0.0700 + X×0.8258 87.62amu = 0.469896amu + 8.4706amu + 6.089363amu + 0.8258 X 87.62amu = 15.029859amu + 0.8258 X 72.590141amu = 0.8258 X 87.90amu = X 88 Sr = 87.90amu 7) 100% - 0.15% - 10.10% - 17.00% - 23.10% - 13.20% - 6.80% = 29.65% 8) Abundance of 29 14 Si = 100% - 92.23% - 3.10% = 4.67% 28.086 = 27.9769×0.9223 + X×0.0467 + 29.9738×0.0310 28.086 = 25.8031 + 0.0467 X + 0.92919 1.353712 = 0.0467 X 28.99 = X 29 14 Si = 28.99amu