Question

Why is the average atomic mass used when calculating grams of a

substance?
A. The exact weights of the isotopes are not known.
B. The elements in the substance are mixtures of their isotopes.
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C. The average atomic mass is known to more significant figures.
D. The number of isotopes in the sample is constantly changing.

Answer 1

The average atomic mass is used when calculating grams of a substance because elements exist as mixtures of isotopes. By considering the masses of different isotopes and their abundances, we can find the average mass of the atoms of an element.

Step-by-step explanation:

In chemistry, the average atomic mass is used when calculating grams of a substance because most elements exist as mixtures of several stable isotopes. The atomic mass of an element is defined as the weighted average of the masses of the isotopes. By considering the masses of the different isotopes and their abundances, we can find the average mass of the atoms of an element. This allows us to accurately calculate the grams of a substance based on its atomic mass.