Question

directions: drag the number of isotope atoms indicated below into the black box in the simulation.
number of atoms for each isotope:

• hydrogen - 1 = 2 atoms
• hydrogen - 2 = 2 atoms

answer the following questions based on the percent composition and average atomic mass data:

1. what is the percent composition of hydrogen - 1? type a number! % only
2. what is the percent composition of hydrogen - 2? type a number! % only
3. what is the average atomic mass of the two isotopes? only type a number, round to 2 decimal places! amu

Explanation:

Step1: Calculate the total number of atoms

The total number of atoms is the sum of the number of Hydrogen - 1 and Hydrogen - 2 atoms.
$2 + 2=4$ atoms.

Step2: Calculate the percent composition of Hydrogen - 1

The formula for percent composition is $\frac{\text{Number of atoms of a particular isotope}}{\text{Total number of atoms}}\times100\%$.
For Hydrogen - 1: $\frac{2}{4}\times100\% = 50\%$.

Step3: Calculate the percent composition of Hydrogen - 2

Using the same formula, for Hydrogen - 2: $\frac{2}{4}\times100\%=50\%$.

Step4: Calculate the average atomic mass

The formula for average atomic mass ($\bar{M}$) when there are two isotopes $M_1$ (mass of isotope 1) and $M_2$ (mass of isotope 2) with abundances $x_1$ and $x_2$ (in decimal form) is $\bar{M}=M_1x_1 + M_2x_2$.
The mass of Hydrogen - 1 ($M_1$) is $1$ amu and the mass of Hydrogen - 2 ($M_2$) is $2$ amu. The abundances $x_1=x_2 = 0.5$.
$\bar{M}=(1\times0.5)+(2\times0.5)=0.5 + 1=1.50$ amu.

Answer:

1. $50$
2. $50$
3. $1.50$