Question

A certain element exists as two different isotopes. 65.0% of its atoms have a mass of 24 amu and 35.0% of its atoms have a mass of 26 amu. What is the average atomic mass of this element?
amu

Answer 1

Answer:

24.7 amu

Explanation:

An isotope is when an element can have different number of neutrons but they have same number of protons.

In order to calculate the average atomic mass with the given information do the following operations:

First change de percentages to fractional numbers, divide by 100.

I like to make a table, to organize all data and I believe is easier to understand.

65/100 = 0.65

35/100 = 0.35

% fraction

65.0 0.65

35.0 0.35

total100.0 1

Now multiply each mass with their corresponding fraction

24 (0.65) = 15.6

26 (0.35) = 9.1

%    fraction uma uma

65.0 0.65 24 15.6

35.0 0.35 26 9.1

total100.0    1          24.7

Finally you add the resulting mass and the units will be in uma.

15.6+9.1 = 24.7

Therefore the average atomic mass of this element will be 24.7 uma.

Check the table in the document attached

Download xlsx