1. 15 grams of solid NaOH was dissolved in 325 mL of water at 21 °C. [15 points]


a. what is the enthalpy of the above reaction ?

b. what is the change in the temperature of water ?

c. what is the final temperature of water ?

 

2. Determine ∆H for the reaction [15 points]

C6H4(OH)2 (aq) + H2O2 (aq)  -->  C6H4O2 (aq) + 2 H2O (l)

using the following information

C6H4(OH)2 (aq) -->  C6H4O2 (aq) + H2 (g)               ∆H1 = 177.4 kJ

H2 (g) + ½ O2 (g) -->  H2O (g)                                 ∆H2 = - 241.8 kJ

H2 (g) + O2 (g) -->  H2O2 (aq)                                   ∆H3 = - 191.2 kJ

H2O (g) -->  H2O (l)                                                ∆H4 = - 43.8 kJ

3. 5.0 grams of benzoic acid dissolved in 100. grams of carbon tetrachloride has a boiling point of 77.5 °C. [15 points]

a. what is the molality of benzoic acid in solution ?

b. how many moles of benzoic acid was dissolved in the solution ?

c. what is the molar mass of benzoic acid ?

4. 25 mL ethylene glycol (density = 1.114 g / mL; molar mass = 62 g / mol) and 25 mL water were mixed to form a solution. [15 points]

a. what is the molarity of ethylene glycol in the solution ?

b. what is the molality of ethylene glycol in the solution ?

c. what is the mole fraction of ethylene glycol in the solution ?