Ch. 5, 19, 8.9, 11.4 thermodynamics                         [100 points]                 AP Chemistry

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

 

1.   How much heat would be generated by the combustion of 1.5 grams of C3 H7 OH  ?   [20 points]

2.   heating curve.

Ethanol (i.e. alcohol with an ethyl group)                                          
ΔHfusion = 109 J / g                                                                   boiling point  =  78 °C
ΔHvaporization  = 35.3 kJ / mole                                                   melting point  =  - 114 °C

Specific heat (J / (g K))                      
liquid  =  2.44
gas =  1.4
solid  =  0.97

Based on the above information, calculate the amount of heat (in kJ) to change 5.0 grams of ethanol at – 25 °C to 100 °C  ?  [20 points]


3.  Determine Δ Hf (NO3 - ) based on the following (hypothetical) experimental results. The initial and final temperature of water was 21.0 and 15.0 °C, respectively after dissolving 2.0 grams of solid ammonium nitrate in 50.0 mL of water. The specific heat of water is 4.18 J / g K. [20 points]


a. write the chemical equation that describes this reaction.

b. Based upon the above experimental data, determine ∆HRx (to dissolve 1 mole of NH4 NO3 in water)

c. Based upon the above experimental data, determine Δ Hf (NO3 - ).


4.  Using thermodynamics, determine the boiling point of butane (C4 H10 )  [assume ∆H, ∆S, & ∆G are independent of temperature; 15 points]

 

5.  Determine ∆S (i.e. zero, positive, negative, or ambiguous) of the following reactions; rationalize your answer without calculating its value. [10 points]


a. C2 H6 (g) + O2 (g)   -->  CO2 (g) + H2 O (g)

b. dissolve solid ammonium nitrate in water.

 

6.   Would (liquid) hydrogen peroxide spontaneously decompose to form oxygen gas and water (liquid) ?  Justify your response using thermodynamics.  [10 points]

7.  Define the term, specific heat.  [5 points]