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Thermochemistry 3
1.
A) Calculate H (express in both kcal and kJ) for the following reaction based on the thermochemical
information given:
N2H4(l) + 2 H2O2(l)  N2(g) + 4 H2O(l)
The following information is available:
2.
N2H4(l) + O2(g)  N2(g) + 2 H2O(l)
Hrxn = –148.7 kcal
H2(g) + ½ O2(g)  H2O(l)
Hrxn = –68.3 kcal
H2(g) + O2(g)  H2O2(l)
Hrxn = –44.8 kcal
Write the reaction for which the reaction enthalpy is equal to the standard heat of formation for C 5H8O3(l).
3.
A) What quantity of heat is released when 1.00 g of sodium metal reacts with excess water?
2 Na(s) + 2 H2O(l)  2 NaOH(aq) + H2(g)
B) What further quantity of heat is released when the hydrogen gas produced burns with O 2 in the air to form
water (in the vapor state)?
4.
Consider the reaction: 2 PH3(g) + 3 Cl2(g)
 2 PCl3(g) + 3 H2(g)
Note: Value for the heat of formation of PH3(g) is not given in textbook:
All other required Hf are available in the text.
A) Calculate H for this reaction.
B) Calculate the heat absorbed or released when 22.0 g of PH 3 reacts.
PH3(g) Hf = 22.89 kJ/mol