Question

practice
calculate the average atomic mass for each set of isotopes.

1. carbon is the backbone of all organic molecules, including sugars and proteins. 98.93% of carbon occurs as carbon-12, and 1.07% occurs as carbon-13.
2. there is more hydrogen present in the universe than any other element. 99.99% of all hydrogen is the hydrogen-1 isotope. the other 0.01% is hydrogen-2, also called deuterium.

Explanation:

Problem 1: Carbon Isotopes Average Atomic Mass Calculation

Step1: Recall the formula for average atomic mass

The formula for average atomic mass ($A$) is $A = (m_1 \times f_1) + (m_2 \times f_2) + \dots$, where $m_i$ is the mass of isotope $i$ and $f_i$ is the fractional abundance of isotope $i$. For carbon, we have two isotopes: carbon - 12 with mass $m_1 = 12$ amu and fractional abundance $f_1=\frac{98.93}{100}=0.9893$, and carbon - 13 with mass $m_2 = 13$ amu and fractional abundance $f_2=\frac{1.07}{100}=0.0107$.

Step2: Plug in the values into the formula

$$
LATEXBLOCK0
$$

Problem 2: Hydrogen Isotopes Average Atomic Mass Calculation

Step1: Recall the formula for average atomic mass

The formula for average atomic mass ($A$) is $A=(m_1\times f_1)+(m_2\times f_2)+\dots$. For hydrogen, we have two isotopes: hydrogen - 1 (mass $m_1 = 1$ amu) with fractional abundance $f_1=\frac{99.99}{100}=0.9999$, and hydrogen - 2 (deuterium, mass $m_2 = 2$ amu) with fractional abundance $f_2=\frac{0.01}{100}=0.0001$.

Step2: Plug in the values into the formula

$$
LATEXBLOCK0
$$

Answer:

s:

1. The average atomic mass of carbon is $\boldsymbol{12.0107}$ amu.
2. The average atomic mass of hydrogen is $\boldsymbol{1.0001}$ amu.