1. GENERAL CHEMISTRY-I (1411)
S.I. # 21
1. Define the following:
a. Enthalpy:
b. Enthalpy of reaction:
c. Calorimetry:
d. Heat capacity:
e. Bomb calorimeter:
f. *Hess’s Law:
g. Enthalpy of formation:
h. Standard Enthalpy change:
i. Standard Enthalpy of formation:
2. The decomposition of zinc carbonate, ZnCO3 (s), into zinc oxide, ZnO (s), and
CO2(g) at constant pressure requires the addition of 71.5 kJ of heat per mole of
ZnCO3. a) Write a balanced thermochemical equation for the reaction. b) Draw an
enthalpy diagram fro the reaction.

2. 3. Consider the reaction: CH3OH (g)  CO (g) + 2H2 (g) ∆H = +90.7 kJ
a) Is the heat absorbed or evolved in the course of this reaction? Is the reaction endo
or exo? b) Calculate the amount of heat transferred when 45.0 g of CH3OH (g) is
decomposed by this reaction at constant pressure. c) For a given sample of CH3OH,
the enthalpy change on reaction is 18.5 kJ. How many grams of hydrogen gas are
produced? d) what is the value of ∆H for the reverse of the previous reaction? How
many kilojoules of heat are released when 27.0 g of CO (g) reacts completely with H2
(g) to form CH3OH (g) at constant pressure?
4. Use: 2KClO3 (s)  2 KCl (s) + 3 O2(g) ∆H = -89.4 kJ
For this reaction, calculate ∆H for the formation of a) 0.855 mol of O2 and b) 10.75 g
of KCl.
5. When 418 J of heat is added to a gas under constant atmospheric pressure, it
expands and does 107 J of work on the surroundings. What are the values of ∆H
and ∆E for this process?
6. The specific heat of ethylene glycol is 2.42 J/g-K. How many J of heat are needed
to raise the temperature of 62.0 g of ethylene glycol from 15.2 °C to 40.8 °C?