5 Steps to a 5 AP Chemistry

9.Under standard conditions calcium metal reacts

readily with chlorine gas. What conclusions may

be drawn from this fact?

(A) Keq<1 and ΔG°> 0

(B) Keq>1 and ΔG°= 0

(C) Keq<1 and ΔG°< 0

(D)Keq>1 and ΔG°< 0

(E) Keq>1 and ΔG°> 0

10.Which of the following combinations is true
when sodium chloride melts?

(A) ΔH>0 and ΔS> 0

(B) ΔH=0 and ΔS> 0

(C) ΔH>0 and ΔS< 0

(D)ΔH<0 and ΔS< 0

(E) ΔH<0 and ΔS> 0

11.Which of the following reactions have a negative
entropy change?

I. 2 H 2 (g) +O 2 (g) →2 H 2 O(l)

II. 2 NH 3 (g) →N 2 (g) +3 H 2 (g)

III. Ca(s) +Cl 2 (g) →CaCl 2 (s)

(A) II only

(B) I only

(C) I, II, and III

(D) III only

(E) I and III

12.A certain reaction is non-spontaneous under
standard conditions, but becomes spontaneous at
higher temperatures. What conclusions may be
drawn under standard conditions?

(A) ΔH<0, ΔS>0, and ΔG> 0

(B) ΔH>0, ΔS<0, and ΔG> 0

(C) ΔH>0, ΔS>0, and ΔG> 0

(D)ΔH<0, ΔS<0, and ΔG> 0

(E) ΔH>0, ΔS>0, and ΔG= 0

13.2 H 2 (g) +O 2 (g) →2 H 2 O(g)

From the table below, determine the enthalpy

change for the above reaction.

AVERAGE BOND ENERGY

BOND (kJ/mol)

H–H 436

O=O 499

H–O 464

(A) 0 kJ

(B) 485 kJ

(C) −485 kJ

(D) 464 kJ

(E) 443 kJ

14.What is the energy required to convert a gaseous

atom, in the ground state, to a gaseous cation?

(A) ionization energy

(B) kinetic energy

(C) activation energy

(D) lattice energy

(E) free energy

15.Which of the following reactions would be

accompanied by the greatest decrease in entropy?

(A) N 2 (g) +3 H 2 (g) →2 NH 3 (g)

(B) C(s) +O 2 (g) →CO 2 (g)

(C) 2 H 2 (g) +O 2 (g) →2 H 2 O(g)

(D) 2 Na(s) +Cl 2 (g) →2 NaCl(s)

(E) 2 KClO 3 (s) →2 KCl(s) +3 O 2 (g)

16.CO(g) +2 H 2 (g) →CH 3 OH(g) ΔH=−91kJ

Determine ΔH for the above reaction if

CH 3 OH(l) were formed in the above reaction

instead of CH 3 OH(g). The ΔHof vaporization

for CH 3 OH is 37 kJ/mol.

(A) −128 kJ

(B) −54 kJ

(C) +128 kJ

(D)+54 kJ

(E) −37 kJ

17.A solution is prepared by dissolving solid ammo-

nium nitrate, NH 4 NO 3 , in water. The initial

temperature of the water was 25°C, but after the

solid had dissolved, the temperature had fallen to

20 °C. What conclusions may be made about ΔH

and ΔS?

(A) ΔH< 0 ΔS> 0

(B) ΔH> 0 ΔS> 0

(C) ΔH> 0 ΔS< 0

(D)ΔH< 0 ΔS< 0

(E) ΔH= 0 ΔS> 0

Thermodynamics  133