Explore BrainMass

Energetics and Thermodynamics

15 Thermodynamics Problems (Delta G, Delta S, Delta H)

1) From the following Ho and So values predict which of reactions I, II, and III would be spontaneous at 300ºC. H (kJ) S(J/K) I -5.0 -15 II -10.0 +20 III -5.0 -30 A. I B. II C. III D. I and II E. II and III 2) From the following Ho and So values predict which of reactions I, II, and

Iron-Sulfur Combination

1) What kind of substance is iron-sulfur combination before heating? 2) Why is it necessary to heat the test tube in order for a chemical reaction to occur? 3) What kind of substance is iron-sulfur combination after heating? 4) The element sodium reacts explosively with water and the element chlorine is a yellow-green p

heat needed to raise the temperature of liquid water

What is the molar heat capacity of liquid water? What is the heat capacity of 160 grams of liquid water? How many kJ of heat are needed to raise the temperature of 15.00g of liquid water from 24.8 C to 46.3 C?

Calculating the amount of heat transferred

Consider the following reaction: CH3OH -->CO + 2H2 Delta H= 90.7 kJ Calculate the amount of heat transferred when 49.0g of CH3OH is decomposed by this reaction at constant pressure. For a given sample of CH3OH, the enthalpy change on reaction is 16.5kJ . How many grams of hydrogen gas are produced? What is the val

The solution to Enthalpy change

Consider the following reaction: 2Mg + 02 --> 2MgO Delta H = -1204kJ Calculate the amount of heat transferred when 2.2g of Mg reacts at constant pressure. How many grams of MgO are produced during an enthalpy change of -94.0kJ ? How many kilojoules of heat are absorbed when 7.80g of MgO is decomposed into Mg and

Why Did I Get Strange Results With My Distillation Unknown?

I performed a lab that dealt with finding the melting point of an unknown liquid. The possible liquids are Acetone (56.5 C) Methanol (65.0 C) Ethanol (78.5 C) Isopropanol (82.4 C) Isopropyl acetate (88.8 C) Water (100 C) Toleuene (110.6) Methyl isobutyl ketone (116.9) and 2-Methoxyethanol (124.0 C). I did the distallation a

Calculate Ke of Given Substrates

1, Calculate Ke for the following (equilibrium concentrations given below substances) a) N2 (g) + O2 (g) + heat ↔ 2 NO (g) [0.13] [0.27] [0.346] b) 2 NH3 (g) ↔ N2 (g) + 3 H2 (g) + heat [0.011] [0.224]

Classic heat transfer/heat capacity problem

A 15.00 g iron block is dropped into a beaker containing 100.0 g of water at 20.00 degrees C. At equilibrium, the temperature of the water is 22.00 degrees C. What was the initial temperature of the block? c(water) = 4.180 J/g/ degrees C and c(Fe) = 0.449 J/g/ degrees C.

Calculations for Delta G

Nitric oxide reacts with chlorine to form NOCL. The data reflects 298K. 2NO(g) + Cl2(g) --> 2NOCl(g) Substance NO(g) Cl2(g) NOCl(g) Delta H(f) (kJ/mol) 90.29 0 51.79 Delta G(f) (kJ/mol) 86.60 0 66.0

calculate the equilibrium constant Kp

The water - gas shift reaction plays an important role in the production of clean fuel from coal. CO(g) + H20(g) <--> CO2(g) + H2 (g) Given Data: Substance = CO(g) H20(g) CO2(g) H2(g) Delta H (KJ/Mol) -110.5 -241.8 -393.5 0 Delta S (

Free Energy - Calculate Delta G

H2(g) + I2(g) = 2HI(g) The delta G for the reaction is 2.60 kj/mol at 25 degrees C. The initial pressures are P H2 = 3.34 atm, P I2 = 0.024 atm and P HI = 0.24 atm. What is the delta G for the reaction in kj/mol?

Vapor pressure as a function of temperature

For organic compounds such as methanol, formaldehyde, phenol, and acetaldehyde, can someone please explain to me how temperature affects vapor pressure of the compound? How would I calculate the vapor pressure of these compounds over a given temperature range assuming 1 mole of each compound?

Free Energy of Formation

5. An inventor decides to make batteries from old aluminum cans and rusty scrap iron, the thought being that the reaction Fe2O3 + Al -> Al2O3 + Fe should generate electric power. Using the free energy of formation find the standard electrode potential for this reaction. What masses of Fe2O3 and Al would be needed to generate 1 J

Temperature for Partial Pressure

Consider the reaction FeO(s) + H2(g) -> Fe(s) + H2O(g). At what temperature would the partial pressure of H2 equal the partial pressure of H2O? See attached file for full problem description.

Reaction at Temperature

Consider the following exothermic gas phase reaction: 2CO + O2 -> 2CO2. Would the reaction be spontaneous at high temperature, low temperature, or all temperatures? Explain.

Chemistry Questions

1) If a system loses 300 kJ of heat at the same time that it is doing 600 kJ of work, what is the change in the internal energy of the system? 2) Which of the following equations represents a reaction that provides the heat of formation of sodium hypochlorite (NaOCl)? 3) The heat of combustion for 1 mole of carbon to ca

Hess's Law of Heat Summation

When 39.5 mL of 0.525 M (H4)(SO4) is added to 39.5 mL of 1.05 M KOH in a coffee-cup calorimeter at at 23.50 C, the temperature rises to 30.17 C. Calculate the H of this reaction (Assume that the total volume is the sum of the individual volumes and that the density and specific heat capacity of the solution are the same as for p

heat released for every 1.00 g of sucrose oxidation

determine how much heat is released for every 1.00 g of sucrose oxidized from the following: Sucrose C12H22O11 is oxidized in the body by O2 that ultimately produces CO2(g) and H2O (g) and releases 5.64 E3 kJ/mol sucrose. This is what I come up with for the balanced equation: 1 C12H22O11 (s) + 12 O2 (g) ----- 12 CO2 (

Calculate Energy Required

The specific heat of fusion of silver is 30.0 calories per gram and the specific heat of silver is 0.30 Joules per gram per degree C. Calculate the energy required to melt 5.0 moles of silver if it starts as a solid at 25 degree C below its normal melting point and is heated to exactly 0.01 Celsius degree above its normal meltin

Increase in Entropy

Thinking about entropy as disordered states, which of the following reactions would show an increase in entropy? Mark those in which entropy increases as TRUE. None of these reactions are balanced. H2 + O2 &#8594; H2O 1. True 2. False CaCO3 &#8594; CaO + CO2 1. True 2. False H2O(l) &#8594; H2O

Metals and Water

Which of the following metals would be the least safe to drop in water? Why? A. lithium B. magnesium C. iron D. potassium E. aluminum.


In a particular reaction, the system does work on the surroundings and absorbs heat rom the surroundings. What is the sign of the internal energy change, ^U? A. always negative B. always positive C. positive or negative depending on the relative magnitudes of the energy transfers D. always zero


The correct equation for which the enthalpy change defines the standard enthalpy of formation for C2H5OH (l) is : A. CH2 + CH2 + H2O -->CH3CH2OH B. CH3CHO + H2 -->CH3CH2OH C. 4 C + 6 H2 + O2 --> 2 CH3CH2OH D. 2C + 3H2 + 1/2 O2 -->2 C2H5OH E. 2C + 6H + O --> C2H5OH


For the following reaction, what is the enthalpy of cyclization per mole of actylene? 3C2H2 (g) --> C6H6 (l) ^H = -630 kJ A. 210 kJ/mol C2H2 B. -630 kJ/mol C2H2 C. 0 kJ/mol C2H2 D. -210 kJ/mol C2H2 E. -1890 kJ/mol C2H2


At 25 degrees C and constant pressure, carbon monoxide gas combines with oxygen gas to give carbon dioxide gas with the evolution of 10.1 kJ per gram of carbon monoxide consumed. What is the value of ^H for the balanced reaction? A. -566 kJ/MOL B. -283 kJ/MOL C. 283 kJ.MOL D. 141 kJ/MOL E. -141 kJ/MOL


What mass of oxygen gas, measured at 238 K and 3.51 atm, is required in ordered to release 6670 kJ of heat to the surroundings? CH4 + 2O2 --> CO2 + 2H20 ^H = 890.3 kJ A. 240 B. 6260 C. 0.574 D. 479 E. 7.49


Calculate the heat capacity of a sample of radiator coolant if a temperature rise from -5 degrees C to 142 degrees C requires 932J of heat? A. 0.158 J/C B. 1.37 x 10 to the power of 5 J/C C. 6.80 J/C D. 6.56 J/C E. 6.34 J/C

Specific Heat and Calculating Final Temperatures

A 15.) g block of aluminum at an initial temperature of 27 C absorbs 0.678 kJ of heat. What is the final temperature of the block? The specific heat of Al is 0.902 J g-1C-1. A. 50.1 C B. 38.6 C C 54.5 C D. 68.6 C E. 77.6 C.