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Energetics and Thermodynamics

Change in internal energy

If the change in internal energy (Delta U), for a system is 217 J in a process in which the system absorbs 165 cal of heat, how much work, in joules, must have been involved?

Calorimetry Lab - Enthalpy Change of a Chemical Reaction

Procedure: 1. Take a calorimeter from the glassware shelf and place it on the workbench. 2. Take a balance from the tools shelf and drop it on the calorimeter. Record the mass of the empty calorimeter. 3. Take a thermometer from the tools shelf and drop it onto the calorimeter. Record the temperature of the calorimete

Enthalpy and Entropy

1. In the rusting of iron delta H= -376.44 kcal/mol K; delta S = -0.1708 dcal/mol K and delta G = 329.8 dcal/mol. Is it driven by enthalpy or entropy? Please explain. 2. Entropy is a measure of the amount of "disorder" in a system. Increase in disorder means high entropy,while increase in order means low entropy. If you were

Enthalpy - Dissolution of Urea Lab Project and Two Questions

Scenario: In lab, we added 4 (g) "solid" Urea CO(NH2)2 to a beaker and filled a buret with 50 ml H2O. We then attached a thermometer to the beaker. We added 1 ml of H2O from buret until "solid" Urea dissolved. We had to record the temperature with each 1 ml added. We had to repeat this experiment 2 more times using diffe

Entropy, Free Energy, Equilibrium

1. Define entropy and relate to probability of microstate formation. 2. Relate entropy and reaction spontaneity, Gibbs free energy and reaction spontaneity, and Gibbs free energy and the equilibrium constant of a reaction. 3. Calculate the entropy change within a system and determine absolute entropies. 4. In your own w

Heat of Fusion

A 35.8-g sample of cadmium metal was melted by an electric heater providing 4.55 J/s of heat. If it took 7.09 min from the time the metal began to melt until it was completely melted, what is the heat of fusion per mole of cadmium?

Specific Heats and Atomic Masses Using a Calorimeter

ChemLab program "specific heat" lab. Obtain 100 g shots of each: iron; copper & aluminum. Insert 150 ml of water at room temperature and heat to a final temperature of 100 degrees of celsius. Place in calorimeter and add 100 ml of water 20 degrees celsius. Measure specific heat for each metal and atomic weight. 100

Diels Alder Reactions of Cyclopentadiene

1) Why does cyclopentadiene dimerize so easily and rapidly to dicyclopentadiene? Please explain your answer. 2) Why must the distillation head temperature be maintained below 45oC suring the cracking of dicyclopentadiene? In other words, in the cracking of dicyclopentadiene, why is it necessary to distill the product very slowl

Exothermic Reaction

Consider the exothermic reaction 2NO(g) + Br2(g) <----> 2NOBr(g). What can you do to the reaction mixture to produce more NOBr? (Choose from the following choices:) (a)Decrease T (b)Remove Br2 (c)Add Br2 (d)Add NOBr (e)Decrease P (f)Remove NO (g)Increase T (h)Add NO (i)Remove NOBr (j)Increase P

Vapor Pressure

At 48 degrees Celsius the vapor pressure of pure ethanol is 180 Torr. What is the vapor pressure of ethanol in a 40% by mass alcoholic beverage heated to 48 degrees Celsius? (In Torr)

Heat of Vaporization

How many grams of propane must be burned to supply the heat required to vaporize 0.680 L of water at 298 K? C3H8(g) + 5 O2(g)-----> 3 CO2(g) + 4 H2O(l) Change of Heat = -2.22 x 10^3 kJ H2O(l) ------> H2O(g) Change of Heat of Vapn. = 44.0 kJ

Thermal effects: Transformation from solid to gaseous state

Calculate the heat (in KJ) required to transform 43.90 g of hydrazine from a solid at a temperature of 1.4 degreed C to a gas at 128 degrees C. report your answer to one decimal place. Data: molar mass of hydrazine: 32.045 g/mol melting point = 1.4 degrees C Boiling point = 114 degrees C Enthalpy of fusion = 12.6 KJ/mol

Net Ionic Reactions of Metal Chlorides

Add 2 mL each of silver nitrate [AgNO3], lead nitrate [Pb(NO3)2] and mercury(I) nitrate[Hg(NO3)2] to the test tube. The chlorides formed are: AgCl, PbCl2, Hg2Cl2. The mixture of the 3 above compounds once precipitated is added water and then heated to to 70C to get [Pb(NO3)2] to disolve it back into solution. PRECIPITATION B

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 Capacity

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

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

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.