A charged particle is caused to move between two electrically charged plates, as shown here. () (+) (a) Why does the path of the charged particle bend? (b) What is the sign of the electrical charge on the particle? (c) As the charge on the plates is increased, would you expect the bending to increase, decrease, or stay the same? (d) As the mass of the particle is increased while the speed of the particles remains the same, would you expect the bending to increase, decrease, or stay the same? [Section 2.2]
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Textbook Solutions for Chemistry: The Central Science
Question
There are two different isotopes of bromine atoms. Under normal conditions, elemental bromine consists of \(\mathrm{Br}_{2}\) molecules, and the mass of a \(\mathrm{Br}_{2}\) molecule is the sum of the masses of the two atoms in the molecule. The mass spectrum of \(\mathrm{Br}_{2}\) consists of three peaks:
\(\begin{array}{c|c} \hline \text { Mass (amu) } & \text { Relative Size } \\ \hline 157.836 & 0.2569 \\ 159.834 & 0.4999 \\ 161.832 & 0.2431 \\ \hline \end{array}\)
(a) What is the origin of each peak (of what isotopes does each consist)?
(b) What is the mass of each isotope?
(c) Determine the average molecular mass of a \(\mathrm{Br}_{2}\) molecule.
(d) Determine the average atomic mass of a bromine atom.
(e) Calculate the abundances of the two isotopes.
Solution
Step 1 of 6
In a mass spectrum of \({\rm{B}}{{\rm{r}}_2}\), each peak corresponds to a molecule made up of different combinations of bromine isotopes. Bromine has two stable isotopes, \(^{79}{\rm{Br}}\) and \(^{81}{\rm{Br}}\). The average atomic mass of bromine is the weighted average of the masses of its isotopes based on their natural abundances.
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