Question

isotopes - problems
given the information below, calculate the average atomic mass of silicon. round your answer to 2 decimal places.
% mass (amu)
$_{26}^{54}$fe 5.8 53.94
$_{26}^{56}$fe 91.8 55.93
$_{26}^{57}$fe 2.4 56.94
average atomic mass = amu

Explanation:

Step1: Convert percentages to decimals

$5.8\% = 0.058$, $91.8\%=0.918$, $2.4\% = 0.024$

Step2: Calculate the contribution of each isotope

For $^{54}_{26}\text{Fe}$: $0.058\times53.94 = 3.12852$
For $^{56}_{26}\text{Fe}$: $0.918\times55.93=51.34374$
For $^{57}_{26}\text{Fe}$: $0.024\times56.94 = 1.36656$

Step3: Sum up the contributions

$3.12852 + 51.34374+1.36656=55.83882$

Answer:

$55.84$