1. As pure elements, all of the halogens are diatomic molecular species. Their m
ID: 797404 • Letter: 1
Question
1. As pure elements, all of the halogens are diatomic molecular species. Their melting points are: F2, 85 K,
Cl2, 239 K, Br2, 332 K, and I2, 457 K. Using the Periodic Table, predict as best you can the molecular
formula of elemental astatine,At, the only radioactive element in this family. Also predict whether it will
be a solid, liquid, or gas at room temperature.
a. Elemental formula: ____________ b. Phase at room temperature: _____________
2. Substances A, B, and C can all act as oxidizing agents. In solution,A is green, B is yellow, and C is red. In
the reactions in which they participate, they are reduced to A?, B ?, and C ? ions, all of which are colorless.
When a solution of C is mixed with one containing B? ions, the color changes from red to yellow.
c. Which species is oxidized? _____________
d. Which is reduced? _____________
e. When a solution of C is mixed with one containing A ? ions, the color remains red.
f. Is C a better oxidizing agent than A? _____________
g. Is C a better oxidizing agent than B? _____________
h. Arrange A, B, and C in order of increasing strength as an oxidizing agent.
3. You are given an unknown, colorless, solution that contains one of the following salts: NaA, NaB, NaC.
In solution, each salt dissociates completely into the Na + ion and the anion A ?, B ?, or C ?, whose
properties are given in Problem 2. The Na + ion is effectively inert. Given the availability of solutions of
A, B, and C, develop a simple procedure for identifying the salt that is present in your unknown.
Explanation / Answer
1. As pure elements, all of the halogens are diatomic molecular species. Their melting points are: F2, 85 K,
Cl2, 239 K, Br2, 332 K, and I2, 457 K. Using the Periodic Table, predict as best you can the molecular
formula of elemental astatine,At, the only radioactive element in this family. Also predict whether it will
be a solid, liquid, or gas at room temperature.
a. Elemental formula: _____At_______ b. Phase at room temperature: ____solid_________
2. Substances A, B, and C can all act as oxidizing agents. In solution,A is green, B is yellow, and C is red. In
the reactions in which they participate, they are reduced to A?, B ?, and C ? ions, all of which are colorless.
When a solution of C is mixed with one containing B? ions, the color changes from red to yellow.
c. Which species is oxidized? _____B________
d. Which is reduced? ________C_____
e. When a solution of C is mixed with one containing A ? ions, the color remains red.
f. Is C a better oxidizing agent than A? ____No_________
g. Is C a better oxidizing agent than B? _yes__
h. Arrange A, B, and C in order of increasing strength as an oxidizing agent.
_A >C > B
3. You are given an unknown, colorless, solution that contains one of the following salts: NaA, NaB, NaC.
In solution, each salt dissociates completely into the Na + ion and the anion A ?, B ?, or C ?, whose
properties are given in Problem 2. The Na + ion is effectively inert. Given the availability of solutions of
A, B, and C, develop a simple procedure for identifying the salt that is present in your unknown.
NaA +C ......>change incolour
NaA +B ......>change incolour
so the given salt is NaA
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.