Average Atomic Mass How to use relative abundance to calculate average atomic mass.

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Average Atomic Mass & % Abundance

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Presentation transcript:

Average Atomic Mass How to use relative abundance to calculate average atomic mass

Relative Abundance

Calculating Average Atomic Mass 1.Take the percent of relative abundance and convert into a decimal by moving the decimal two places to the left. 2.Multiply the new decimal by the mass that it goes with 3.Record your number 4.Complete steps 1-3 for all of the isotopes present in the problem 5.Once you have a value for all isotopes add them together.

Examples Rubidium is a soft, silvery-white metal that has two common isotopes, 85 Rb and 87 Rb. If the abundance of 85 Rb is 72.2% and the abundance of 87 Rb is 27.8%, what is the average atomic mass of rubidium? Uranium is used in nuclear reactors and is a rare element on earth. Uranium has three common isotopes. If the abundance of 234 U is 0.01%, the abundance of 235 U is 0.71%, and the abundance of 238 U is 99.28%, what is the average atomic mass of uranium?

Titanium has five common isotopes: 46 Ti (8.0%), 47 Ti (7.8%), 48 Ti (73.4%), 49 Ti (5.5%), 50 Ti (5.3%). What is the average atomic mass of titanium ? Naturally occurring chlorine that is put in pools is percent 35 Cl and percent 37 Cl Calculate the average atomic mass.

Copper used in electric wires comes in two flavors (isotopes): 63 Cu and 65 Cu. 63 Cu has an atomic mass of amu and an abundance of 69.09%. The other isotope, 65 Cu, has an abundance of 30.91%. Calculate the average atomic mass Magnesium consists of three naturally occurring isotopes. The percent abundance of these isotopes is as follows: 24 Mg (78.70%), 25 Mg (10.13%), and 26 Mg (11.7%).