CHEM: Ch17-Spontaneity of Reaction
Predict the signs of delta S and delta H for the freezing of water into ice at 273 degrees
E. delta H < 0 and delta S < 0
If delta G is positive at all temperatures, then which of the following statements must be true
E. delta H > 0 and delta S < 0
All of the following events result in an increase in entropy EXCEPT
E. the formation of N2O2 (g) from NO2 (g)
Place the following gaseous molecules in order from least to greatest entropy
A. H2 < CH4 < C2H6
Which of the following reactions is likely to have the most negative change in entropy
A. NH3 (g) + HCl (g) ---- NH4Cl (s)
What is the correct form of the Gibbs-Hemholtz equation
A. delta G = delta H - T(delta S)
All of the following statements are false for the freezing of water at 273 K EXCEPT
A. delta H < 0
Diluting concentrated sulfuric acid with water can be dangerous. The temperature of the solution can increase rapidly. What are the signs of delta r H, S, and G
A. delta r H < 0 delta r S > 0 delta r G < 0
Rubber elasticity is an entropic phenomenon. As a rubber band is stretched the entropy of the system
A. is reduced
In what temperature range is delta G greater than zero for the formation of NH4Cl(s) from NH3(g) and HCl(g)
A. the temperature must be greater than 619 K
For a chemical reaction delta G and delta G (o) are equal
A. when product and reactants are in standard state concentrations
If delta G is negative at all temperatures, then which of the following statements must be true
C. delta H < 0 and delta S > 0
Predict the sign of delta S and delta H for the combustion of gasoline at 500 K
C. delta H < 0 and delta S > 0
Predict the sign of delta S and delta H for the evaporation of water from a glass
B. delta H > 0 and delta S > 0
The second law of thermodynamics states that
B. in spontaneous process there is a net increase in entropy, taking into account the systems and surroundings
All of the following statements are true EXCEPT
B. the entropy for gaseous elements is zero at 298 K
Which of the following reactions is likely to have the most positive change in entropy
C. 2C (s) + O2 (g) ---- 2CO (g)
Which of the following statements concerning entropy is/are CORRECT 1. the entropy of a substance decreases when converted from a liquid to a gas 2. the entropy of a substance decreases as its temperature increases 3. negative entropy values cannot exist
C. 3 only
For which of the following molecules does delta G(f) equal zero
C. CO2 (s)
If delta G > 0 then
C. K < 1
All of the following statements are true EXCEPT
C. if delta G = 0 then delta S = delta H
All of the following statements are true EXCEPT
C. reactions are spontaneous when delta H < 0
Predict the signs of delta G, delta H, delta S for the combustion of octane
E. delta G < 0, delta H < 0, delta S > 0
In a gas phase reaction what is the effect of increasing reactant or product pressure on the standard Gibbs free energy
E. delta G is unchanged
Which of the following are conditions for the standard Gibbs free energy 1. Ions or molecules in solution are present at one molar concentrations 2. Gases are present at one atm partial pressure 3. The temperature of the system is 273 K
D. 1 and 2
Which of the following reactions is likely to have the smallest change in entropy
D. O2 (g) + N2 (g) ---- 2NO (g)
For the decomposition of hydrogen peroxide to water and oxygen. In what temperature range is the reaction spontaneous
D. delta G is always less than zero
When ammonium nitrate dissolves spontaneously in water the temperature of the solution decreases. Which statement is true for this system
D. delta H > 0 and delta S > 0
If a chemical reaction has a negative change in entropy (delta S) then,
D. there is an increase in the order of the system
All of the following statements are false for the spontaneous combustion of hydrogen gas at 400 K EXCEPT
E. delta H < 0
Which of the following molecules is likely to have the greatest entropy in the gaseous state
E. C4H10
For a chemical reaction, if delta r G = 0 then
E. K=1
