CHEM 1112 Chapter Notes - Chapter 14: Allotropy, Molar Mass, Spontaneous Process

71 views8 pages

indigoseal843

22 Feb 2017

School

Department

Course

Professor

For unlimited access to Textbook Notes, a Class+ subscription is required.

Document Summary

Spontaneous process: process that does occur under a specific set of conditions, irreversible, occur in one direction. Non-spontaneous process: process that does not occur under a specific set of conditions, occur in the reverse direction. Reversible processes: system changes in a way that the system and surroundings can be put back in their original states by exactly reversing the process. Irreversible processes: cannot be undone by exactly reversing the change to the system, spontaneous processes are irreversible. To predict spontaneity of a chemical or physical process, we need to know both the change in enthalpy and the change in entropy associated with the process. Entropy: measure of how spread out of how dispersed the system"s energy is, for a given system, the greater the volume it occupies, the greater its entropy. Image is a spontaneous process: occurs spontaneously despite there being too entropy change, motional energy.

Related Questions

Model 1 â Spontaneous Processes Process Description Change in Enthalpy (âH) Change in Entropy (âS) Spontaneous? A Two pure â Homogeneous substances mixture ~ 0 Increasing Yes B Solute on Solute on one side of â both sides of membrane membrane ~ 0 Increasing Yes C Polypeptide â Individual chain amino acids Exothermic (negative) Increasing (positive) Yes D C3 H8 + 5O2 â 3CO2 + 4H2 O Exothermic Increasing Yes E 6CO2 + 6H2 O â C6 H12O6 + 6O2 Endothermic Decreasing No F Glucose â Starch Endothermic Decreasing No G Water â Ice Exothermic Decreasing Below 0 Â°C, yes Above 0 Â°C, no H Cold water (25 Â°C) â Hot water (60 Â°C) Endothermic Increasing Below 60 Â°C, no Above 60 Â°C, yes

Some of the processes in Model 1 are spontaneousâthat is, they will occur without any additional work being done on the system. For example, a solute will diffuse across a membrane until the concentrations of both sides are equal. However, glucose will not spontaneously form from carbon dioxide and water in the atmosphere. The Second Law of Thermodynamics states that a process will be spontaneous when it results in an increase of total entropy in the universe. In other words, either the system or the surroundings must have an increase in entropy, or both. (Please note that the term âspontaneousâ does not imply that the change will happen quickly. Rusting is spontaneous under the right conditions, but it can still occur very slowly.)

13. Predict the change in entropy of the surroundings for an endothermic reaction.

DearChegg Lifesaver. Here are the requirements:

1.Use given values as stated in questions below.

2.Clearly State Answer

3.(Please) LEAVE A COMMENT if you are currently working on anyproblems.

4.Formany of these problems you will need to use tabulated thermodynamicdata. Use the Information provided after problem 17.

---------------------------------------Questions---------------------------------------------------

1.Write a balanced formation equation for HNO3 at standardconditions. For the answer, enter the sum all of the coefficientsin the balanced equation. (If thisis not an integer, enter it as a decimal, not a fraction.)

2.Calculate ?HÂ° for the following reaction:

SiO2(s)+ 4HF(g) ? SiF4(g) + 2H2O(g)

3.Use heat of formation data to determine ?HÂ° for the reaction:

2NH3(g)? N2(g) + 3H2(g)

4.Calculate the mass of methane that must be burned to provide enoughheat to convert 330.0 g of water at 37.0Â°C into steam at 124.0Â°C.(Assume that the H2Oproduced in the combustion reaction is steam rather than liquidwater.)

5.Acetylene burns in air according to the following equation:

C2H2(g)+ 5/2 O2(g) ? 2 CO2(g) + H2O(g)

with?HÂ° = -1255.8 kJ.

Giventhat ?HfÂ° for CO2(g) = -393.5 kJ/mol and ?HfÂ° for H2O(g) is -241.8kJ/mol, what is ?HfÂ° for C2H2(g)?

6.Given the following data:

HNO3(l)? 1/2N2(g) + 3/2O2(g) + 1/2H2(g) ?HÂ° = 174.1 kJ

2N2O5(g)? 2N2(g) + 5O2(g) ?HÂ° = -28.4 kJ

H2O(l)? H2(g) + 1/2O2(g) ?HÂ° = 285.8 kJ

Calculate?HÂ° for the reaction:

2HNO3(l)? N2O5(g) + H2O(l)

Notethat you should be able to answer this one without needing to useany additional information from the thermo table.

7.Hydrocarbons containing halogens are very useful molecules insynthetic chemistry. Use tabulated thermodynamic data as needed tocalculate ?HfÂ° for the reactionproduct in the equation shown below if ?HÂ° for the reaction is-177.66 kJ.

C2H4(g)+ Cl2(g) ? CH2ClCH2Cl(g)

8.Identify the following statements as true or false. (Use thedrop-down menu and select "True" or "False" for each. You must getall 6 correct.)

Allsystems become more disordered spontaneously.

Both?Ssys and ?Ssurr must equal zero at equilibrium.

Theentropy of the universe is constant; the energy of the universedecreases towards a minimum.

Allspontaneous processes release heat.

Ifa reaction is spontaneous, the reverse reaction is non-spontaneous.

Ifa process decreases the randomness of the particles of a system,the entropy of the system increases.

9.Use tabulated thermodynamic data to calculate ?SÂ° for the reaction:

PbO2(s)+ 2Ni(s) ? Pb(s) + 2NiO(s)

10.Calculate ?SÂ° for the combustion of ethane (C2H6) to form carbondioxide and gaseous water.

11.Urea ((NH2)2CO) can be formed from ammonia and carbon dioxide asshown in the following reaction. The ?HÂ° value for this synthesisis -134.0 kJ. Calculatethe ?HÂ°f for urea.

2NH3(g)+ CO2(g) ? (NH2)2CO(s) + H2O(l)

12.The ?SÂ° value for urea the synthesis reaction above is -424.0 J/K.Calculate SÂ° for urea.

Tries0/99

13.Calculate ?GÂ° for the synthesis of urea under standard conditions(298 K and 1 atm).

Tries0/99

14.Compute the standard free energy change for the following reaction.

O3(g)+ NO(g) ? NO2(g) + O2(g)

Tries0/99

15.The most important commercial process for generating hydrogen gasis the water-gas shift reaction:

CH4(g)+ H2O(g) ? CO(g) + 3H2(g)

Usetabulated thermodynamic data to find ?GÂ° for this reaction at thestandard temperature of 25Â°C.

16.Now calculate ?GÂ°1100 for this process when it occurs at 1100 K.

17.The molar enthalpy of fusion (?HÂ°) of fluorine is 0.260 kJ/mol, andthe molar entropy of fusion (?SÂ°) of fluorine is 4.851 J/mol K.Using this information,estimate the freezing point of fluorine. (You must answer inKelvin.)

Any help/explanations with this Le Chatelier's Principle lab would be extremely helpful. I attemtped to do question A, but I'm not exactly sure if my answer is interpreted correctly. I have included the actual lab procedure with the 5 questions. Thank you again.

CHEM 1112 Chapter Notes - Chapter 14: Allotropy, Molar Mass, Spontaneous Process

Document Summary

Get access

Related textbook solutions

Chemistry: Structure and Properties

Basic Chemistry

Principles of Chemistry Molecular Approach

Principles of Chemistry Molecular Approach

Chemistry: Structure and Properties

Chemistry: A Molecular Approach

Chemistry: A Molecular Approach

Principles of Chemistry: A Molecular Approach

Chemistry: The Central Science

Related Documents

CHEM 1112 Chapter Notes - Chapter 15: Partial Pressure, Law And Justice, Chemical Species

CHEM1101 Study Guide - Midterm Guide: Thermodynamics, Statistical Mechanics, Spontaneous Process

CHEM 102 Lecture Notes - Lecture 1: Isothermal Process, Automotive Engine, Thermodynamics

Related Questions