Part Ill: Show all of your work to come up with the solutions to the following questions. You will
get full credit if your setup is correct, even if you might have the wrong numerical answer
(because you punched things into the calculator incorrectly, for example).
7. Molecular nitrogen combines with molecular oxygen to provide Nitrogen monoxide gas,
according to the following equation.
N, (g) + O, (g) - 2 NO(g)
AH = 181 kJ
a. Is this reaction exothermic or endothermic, and how do you know this?
b. If 56g of nitrogen reacts with an excess of oxygen, then how much heat is
absorbed or released in other words, what is the AH for the reaction)?
8. If an object is heated or cooled, what three things determines how much heat energy is
gained or lost by that object (Hint: there is an equation for this that includes those three
things)
9. Calculate the amount of heat required to raise the temperature of 200 ml of water from
20°C to 100 °C. (Density of water = 1,00 g/ ml and specific heat of water = 4.184 J/g.°C).
10. When a light freeze will occur, farmers in Florida spray their orange crops with water
before nightfall. Using what you know about thermochemistry, explain why this helps
protect the oranges from freezing,
