Our professor gave us three questions for our exam tomorrow, I was wondering if anyone would check my work for me. I just want to make sure I am doing this correctly. Thanks in advance.(adsbygoogle = window.adsbygoogle || []).push({});

15) Which of the following species has the largest atomic size:

(a) [tex] S^{2-} [/tex]

(b) [tex] Cl^{-} [/tex]

(c) [tex] Ca^{2+} [/tex]

(d) [tex] Ar [/tex]

15.A:They are an isoelectric series since they have the same number of electrons, thus the largest radius is determined by the isotope with the smallest atomic number, which is:

(a) [tex] S^{2-} [/tex]

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16) Given the following reactions:

[tex] N_{2(g)} + 2O_{2(g)} \longrightarrow 2NO_{2(g)} \,\,\, \Delta H_1 = 66.4kJ [/tex]

[tex] 2NO_{(g)} + O_{2(g)} \longrightarrow 2NO_{2(g)} \,\,\,\Delta H_2 = -114.2kJ [/tex]

What is [itex] \Delta H_{rxn} [/itex] for the following process?

[tex] N_{2(g)} + O_{2(g)} \longrightarrow 2NO(g) [/tex]

(a) 180.6kJ

(b) -47.8kJ

(c) 47.8kJ

(d) 90.3kJ

(e) -180.6kJ

16.A:

[tex] N_{2(g)} + 2O_{2(g)} \longrightarrow 2NO_{2(g)} + \Delta H_1 = 66.4kJ [/tex]

[tex] 2NO_{(g)} + O_{2(g)} \longrightarrow 2NO_{2(g)} + \Delta H_2 = -114.2kJ [/tex]

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[tex] O_{2(g)} \longrightarrow -2NO_{(g)} + 2NO_{2(g)} + \Delta H_2 = -114.2kJ [/tex]

[tex] -O_{2(g)} \longrightarrow 2NO_{(g)} - 2NO_{2(g)} - \Delta H_2 = -114.2kJ [/tex]

[tex] N_{2(g)} + O_{2(g)} \longrightarrow 2NO_{(g)} + \Delta H_1 - \Delta H_2 [/tex]

Thus: [itex] \Delta H_1 - \Delta H_2 = (66.4+114.2)kJ = 180.6kJ [/itex]

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19) All of the following are characteristics of Alkali metals except

(a) They are very reactive.

(b) They have low densities and low melting points

(c) They have high thermal and electrical conductivities

(d) They have a fully filled VE shell of electrons

(e) They react w/ [itex] O_2 [/itex] to form oxides, peroxides, and superoxides.

19.A:

a, b, c, e are all true.

Thus the answer is(d)

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# Homework Help: Intro Chemistry: Does this look ok?

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