1
are spontaneous processes irreversible or reversible?
Are equilibrium processes reversible or irreversible?
reversible
Is the change of enthalpy for an endothermic reactions negative or positive?
Positive
Does H2O (l) or H2O (g) have a higher entropy? Why?
Gas, because of the state
Is something favorable or unfavorable with a large activation energy?
Unfavorable
What is the first Law of Thermodynamics?
Energy can not be created or destroyed
What do kinetics determine for a process under given conditions?
Speed
Is endothermic spontaneous?
No (Usually)
What qualities make a reagent successful for selective precipitation?
The Ksp values are significantly different
If concentrated HCl is added to a solution of various cations and only PbCl2 forms a precipitate, what cation must be present?
Pb2+
What do thermodynamics predict for a process under given conditions?
Spontaneity
Is exothermic spontaneous?
yes
What is the Third Law of Thermodynamic?
For a perfect crystal at absolute zero, absolute entropy is zero
Complex ion formation will do what to the solubility of an ionic compound that contains a metal cation?
Increase
which has s higher entropy between He(g) or Xe (g)? Why?
What are two ways for heat to be lost from the system?
Converted to heat, used to do work
Why are spontaneous processes irreversible (or reversible because I have another question on here)?
There is a net release of energy when it proceeds in one direction.
Is the change of enthalpy for an exothermic reactions negative or positive?
Negative
Can the absolute entropy of substances be negative? Why?
No, perfect crystal, third law of thermodynamics
How do you determine the direction of spontaneity?
Comparing the potential energy of the system before and after a reaction occurs.
1.91 x 10^-23 J/K
What is the entropy with 6 atoms in 12 locations?
9.42 x 10^-23 J/K
Name the following processes as endothermic or exothermic:
vaporization
freezing
sublimation
melting
Endothermic
exo
endo
endo
Should solid PbI2 precipitate of 0.150g aqueous KI is added to 0.8 L of an aqueous solution that is 0.005M in [PbCl3]— and has a [Cl—] of 3.0M. (Kf= 24) (Ksp= 7.1 x 10-9)
No PPT, Kc > Oc
What is the standard enthalpy change at 25°C for the following reaction
C6H12O6 (s)+ 6O2 (g) → 6CO2 (g)+ 6H2O (l)
∆H° (C6H12O6 (s ))= -1273.3 kJ/mol
∆H° (O2 (g))= 0 kJ/mol
∆H° (CO2 (g))= -393.5 kJ/mol
∆H° (H2O (l))= -285.8 kJ/mol
-2802.5 kJ/mol