Examen de Química I URV 2019 · - Diciembre 2019

Pregunta 1 (2 points; 0.25 each). Compound Nomenclature

Provide the systematic IUPAC name for each of the following compounds:

a.

$\text{NH}_4\text{NO}_3$

b.

$\text{HClO}$

c.

$\text{Fe}(\text{HSO}_3)_2$

d.

$\text{AsH}_3$

e.

f.

g.

h.

Pregunta 2 (1.5 points). Stereochemistry and 3D Representations

Which of the following pairs of structures represent the same compound, and which represent different stereoisomers? Use suitable three-dimensional representations to justify your answers.

a)

b)

c)

Pregunta 3 (2 points). Periodic Trends in Ionic Radii

Arrange the following species in order of increasing radius and comment on the principles involved in doing so:

$$\mathrm{Kr},\ \mathrm{Rb}^+,\ \mathrm{Y}^{3+},\ \mathrm{Br}^-,\ \mathrm{Sr}^{2+},\ \mathrm{Se}^{2-}$$

Atomic numbers: $\mathrm{Se}\ (34)$; $\mathrm{Br}\ (35)$; $\mathrm{Kr}\ (36)$; $\mathrm{Rb}\ (37)$; $\mathrm{Sr}\ (38)$; $\mathrm{Y}\ (39)$.

a)

b)

Pregunta 4 (1 point). Energetics of Ion Formation and Reaction Enthalpy

Use ionization energies and electron affinities listed below to determine whether the following reaction is endothermic or exothermic:

$$\mathrm{Mg}(g) + 2\,\mathrm{F}(g) \longrightarrow \mathrm{Mg}^{2+}(g) + 2\,\mathrm{F}^-(g)$$

Property (kJ/mol) · Mg · F

First ionization energy ($IE_1$) · 738 · 1681

Second ionization energy ($IE_2$) · 1451 · 3374

Electron affinity ($EA$) · 40 · $-328$

a)

b)

Endothermic

Exothermic