Ch. 5, 19, & 8.9 thermodynamics            [65 points]                test                      AP Chem


For problems involving calculations, show the relevant equation (or formula, and conversion factor(s)), show your work in an organized manner, put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.

1. Using thermodynamics, in regards to boiling water, determine [assume ∆H, ∆S, & ∆G are independent of temperature; 15 points]

a. the enthalpy of the process

b. the entropy of the process

c. based on the above information, determine the temperature range, where the process is spontaneous.


2. If dissolving 5.0 g NH4NO3 (s) in 50.0 mL water lowers the temperature of water by 3.0 °C, what is Δ Hf (NO3 -) ? [15 points]


3. Determine ∆S (i.e. zero, positive, negative, or ambiguous) of the following reactions; rationalize your answer (do not calculate its value). [10 points]

a. C2H6 (g) + O2 (g)  -->  CO2 (g) + H2O (g)

b. NaCl (aq) + AgNO3 (aq) -->  products


4. In regards to the reaction: CH3Cl (g) + Cl2 (g) -->  HCl (g) + CH2Cl2 (g) [15 points]

a. determine ∆H of the reaction

b. determine ∆H of the reaction: 10.0 g CH3Cl (g) + 20.0 Cl 2 (g) -->  HCl (g) + CH2Cl2 (g)


Old topics [10 points]

5. Describe London intermolecular forces in polar and nonpolar compounds in terms of its dipole moment (define this term).