posted by Skylar .
Potassium has an atomic mass of 39.10amu. a sample of potassium is made up of isotopes potassium-39 (mass=38.964) and potassium-41(mass =40.962 amu). What percentage of the potassium sample is potassium-39? what percent of the sample is potassium-41?
For a sample of K, with x grams of 39K and y grams of 41K the total mass will be
38.964x + 40.962y
Assuming a sample of 100g, we have
38.964x + 40.962(100-x) = 39.10(100)
x = 93.193
39K is 93.193%
41K = 6.807%
38.964*.93193 + 40.962*.06807 = 39.10