GEOL 135
Homework 2
Fall 2007
1. Determine the Heat Capacity (Cp) for muscovite at 25, 500 and 1200ºC using the
Maier-Kelley equation (appropriate data can be found in Appendix F3 of your text).
2. Determine the enthalpy of reaction for each of the following:
a. HCO3- == CO32- + H+
b. Albite + 0.5 H2O + H+ == Na+ + 0.5 Kaolinite + 2 SiO2(aq)
c. Jadeite + Quartz == Albite
3. The origin of red-bed sandstones, in which grains are coated with hematite (Fe2O3),
has long been controversial. A key question in this debate centers around the stability of
hematite in water of low temperature. Calculate whether hematite or goethite (FeOOH),
is stable in water at 25ºC and 1 bar pressure. Gf(hematite)= -178155 cal/mol;
Gf(goethite)= -116766 cal/mol, Gf(H2O)= -56688 cal/mol. (Hint: try to write a reaction
with these 3 phases and use the data supplied to determine which side is
thermodynamically favored).
4. Calculate HR0 and GR0 for the reaction:
Nepheline + 2 Quartz = Albite
A.k.a.
NaAlSiO4 + SiO2 == NaAlSi3O8
Is the reaction endothermic or exothermic, which direction would the reaction go? Why
doesn’t it (i.e. we have samples of both sitting in drawers – the albite stays as is and
sometimes the nepheline touches quartz with no effect)?