Question

A pure sample of bromine was vaporized and injected into a mass spectrometer and the data was plotted on the graph below. The mass value for Br-79 is 78 918 amu Find the mass of Br-81.

Answer 1

Answer:

$m_{Br-81}=80.945amu$

Explanation:

Hello,

In this case, since the percent abundance of Br-79 is 51.1% and that of the Br-81 is 48.9 %, we can write:

$m_{Br}=m_{Br-79}*51.1\%+m_{Br-81}*48.9\%$

Taking into account that the mass of bromine from the periodic table is 79.909 amu, the mass of Br-81 turns out:

$m_{Br-81}=\frac{m_{Br}-m_{Br-79}*51.1\%}{48.9\%} =\frac{79.909amu-78.918*0.511}{0.489} \\\\m_{Br-81}=80.945amu$

Best regards.