Question

1. A 25 grams piece of unknown metal at 80 ºC is dropped into 50 grams of water at 25.0 ºC. The final temperature of the water is 26.16 ºC. What is the specific heat of the unknown metal? [Report answer to two sig figs and do not add the unit label.]

2. Determine the ∆H º for the third reaction; is it exothermic ?

ClO_(g) + O_3(g) --> Cl_(g) + 2 O_2(g)      ∆Hº = -29.90 kJ/mol

2 O_{3(g) -}-> 3 O_2(g)   ∆Hº = +24.18 kJ/mol

Cl_(g) + O_3(g) --> ClO_(g) + O_2(g) ∆Hº = ????

3. Consider the following unbalanced reaction and determine the ∆Hº for the reaction using Appendix G in the back of your book. [Report the answer to three sig figs and without unit labels. Use +/- signs to indicate if the value is endo- or exothermic.]

___NO_2(g) + ___ H₂O_(g) --> ___HNO_3(g) + ____NO_(g)