Study of the transport properties of the mixed ionic electronic
Identify the following as ionic, polar covalent, or nonpolar covalent.
description
Transcript of Identify the following as ionic, polar covalent, or nonpolar covalent.
Identify the following as ionic, polar covalent, or nonpolar covalent.
1. Methane (CH4) 2. Carbon Dioxide 3. Sodium oxide 4. NH3
Reaction Spontaneity
How can a fire start on its own? (without a spark)
Spontaneous Reaction
• Occurs naturally and favors formation of products
4Fe(s) + 3O2(g) 2Fe2O3(s) ΔH = -1625 kJCH4(g) + 2O2(g) CO2(g) + 2H2O(l) ΔH = -891 kJ
Nonspontaneous Reaction
Does not favor formation of products
2Fe2O3(s) 4Fe(s) + 3O2(g) ΔH = 1625 kJCO2(g) + 2H2O(l) CH4(g) + 2O2(g) ΔH = 891 kJH2O(s) H2O(l) ΔH = 6.01 kJ
Some endothermic reactions are SPONTANEOUS!
ENTROPY (S)
• The measure of disorder or randomness of particles in a system
LAW OF DISORDERSpontaneous processes always increase the entropy of a system
Law of Disorder
Changes in Entropy (ΔS)
•Δssystem = Sproducts – Sreactants
1. Changes in State
2. The dissolving of a gas in a solvent always results in a decrease in entropy.
CO2(g) CO2(aq) Δssystem < 0
3. Assuming no change in physical state, the entropy increases when: # of product particles > # of reactant particles.
2SO3(g) 2SO2(g) + O2(g) Δssystem > 0
4. when a solid or a liquid dissolves to form a solution.
NaCl(s) Na+(aq) + Cl-(aq) Δssystem > 0
5. increase in the temperature increase in entropy
Does entropy increase or decrease?
CaCO3 (s) CaO (s) + CO2 (g)
NH3 (g) + HCl (g) NH4Cl (s)
How ΔHsystem and ΔSsystem
affect reaction spontaneity
ΔH ΔS Spontaneous?
- + yes+ + Depends on T- - Depends on T+ - No
Gibb’s Free Energy!!
ΔGsystem = ΔHsystem – TΔSsystem
The energy that is available to do work (useful energy)
ΔGsystem and reaction spontaneity
Type of Reaction or Process
ΔGsystem ΔSuniverse
Spontaneous - +Nonspontaneous + -
Is the following reaction spontaneous?
N2(g) + 3H2(g) 2NH3(g) ΔH°system= -91.8 kJ
ΔS°system= -197 J/K
ΔGsystem = ΔHsystem – TΔSsystem
For a process, ΔHsystem=145 kJ and ΔSsystem=322J/K. Is the reaction spontaneous at 382 K?