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Energetics and Thermodynamics

Heat of Vaporization of White Phosphorus

White phosphorus, P4, is normally a white waxy solid melting at 44 degree Celsius to a colorless liquid. The liquid has a vapor pressure of 400 mmHg at 35 degree Celsius and 760 mmHg at 280 degree Celsius. What is the heat of vaporization of this substance?

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

Work, Power and Enerhgy: Wind Turbines

Could you please explain what formula and step are involved and please provide (example) problem if possible? a)Assume a wind turbine with a hub 50 meters above the ground, a rotor diameter of 75 meters and a wind-conversion efficiency of 25 percent. The turbine operates in an area with an average wind-power density of 650 wa

Exothermic Reaction: Shifting Reactions

Please help with the following physical chemistry problem. 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) Incre

Chemistry: Calculating the Final Temperature

An ice cube weighing 23.4 g at a temperature of 0.0 degrees Celsius is added to 125 mL of water at 24.9 degrees Celsius in an insulated container. After some time the ice cube will have melted, the cold and warm water will mix and reach a final temperature. Start by computing the heat required to melt the ice cube, and think a

heat required to melt an ice cube

How many kilojoules of heat are required to melt an ice cube having the dimensions 3.8 cm x 2.8 cm x 2.1 cm? The density of ice is 0.92 g/cm^3 (cubed). Refer to table: SUBSTANCE MELTING POINT,degrees Celsius Change in Heat of Fusion kJ/mol Mercury -38.9 2.30 E

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

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

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.

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 (

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


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: Heat Absorbed by Copper

Copper clips are sometimes used as "heat sinks." How many grams of copper must be in contact with an electric component to absorb 10.0 J of heat and not let the temperature increase by more than 40 C? The specific heat of copper is 0.385 J/g K.


Calcium carbide (CaC2) reacts with water to form acetylene (C2H2), a gas used as a fuel in welding: CaC2 + 2H2O ==> C2H2 + Ca(OH)2 ^H = 128.0 kJ How many kilograms of CaC2 are consumed in a raction that releases 3.64 x 104 kJ of heat under these conditions? A. 1.82 x 10 to the power of 4 kg B. 284 jg C. -18.2 kg D

Heat applied to water and alcohol

Which of the following liquids has the highest specific heat capacity? water, alcohol, glycerine, or hexane. If you applied equal amounts of heat to equal masses of water and alcohol, which will stay closest to its initial temperature?