2 Which chemical reaction is exothermic and why A 25 degrees after 25 minutes B 23 degrees after 15 minutes C 30 degrees after 25 minutes D 22 degrees after 30 minutes

C 30 degrees after 25 minutes

Explanation:

A reaction is exothermic if heat is evolved as the reaction proceeds. How do we know if heat was given out in the course of the reaction? We have to measure the temperature of the system using a thermometer as  the reaction progresses.

If the temperature becomes higher than room temperature (25 degrees), we can now conclude that the reaction is exothermic and heat was indeed given out during the course of the reaction.

answer : (a) volume of the gas = 8.67 ×   l

                (b) second virial coefficient b = -1.21226 l/mole

solution :   given,     t = 300k

                                p = 20atm

                                z = 0.86

                                n = 8.2 mmoles = 8.2 × moles

                                r =   0.082 l atm/k/mol

        find,     (a) volume of gas   and (b) second virial coefficient b at 300k.

formula used :            

                          and            

(a)            

                    = \times 0.082\times 300}{20}[/tex]

                    = 8.67 ×   l

(b)      

                    = (0.00867-1) × 8.659

                    = - 8.5839 l/mole