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# Energetics and Thermodynamics

### Heat needed to convert ice to liquid water

Calculate the amount of heat that must be absorbed by 10.0 g of ice at -20.0 degrees C to convert it to liquid water at 60.0 degree C. Specific heat (ice) = 2.1 j/g degree C Specific heat (water) delta H (fus)= 6.0 kJ/mol

### the change in enthalpy and entropy

5. C(s) + CO2(g) ---> 2 CO(g) Carbon (graphite), carbon dioxide and carbon monoxide form an equilibrium mixture as represented by the equation above. (a) Predict the sign for the change in entropy, deltaS, for the reaction. Justify your prediction. (b) In the table below are data that show the percent of CO in the equi

### Combustion of Pentane, Enthalpy, and Graham's Law of Diffusion

3. Consider the hydrocarbon pentane, C5H12 (molar mass 72.15 g). (a) Write the balanced equation for the combustion of pentane to yield carbon dioxide and water. (b) What volume of dry carbon dioxide, measured at 25 C and 785 mm Hg, will result from the complete combustion of 2.50 g of pentane? (c) The complete combusti

### Equilibrium Concentration from Thermodynamic Data

For the reaction: A (aq) + B (aq) <----> C (aq) you find the following thermodynamic data: the standard reaction enthalpy, (delta Hr^0)= 9.629 kJ/mol the standard reaction entropy, (delta Sr^0)= 16.66 J/(mol K) Say, you prepared a mixture with initial concentrations [A]0=[B]0= 1 mol/L, and [C]0 = 0, and waited until the m

### Urea - Heat of Dissolution Laboratory

Hello! I have two different experiments attached, please put them in Standard Deviation. For example: Experiment 1: Keq=____,(delta)H=___J, (delta)G = _____, (delta)S =____J/K Experiment 2: Experiment 3: Standard Deviation for Keq: mean=_____ St.Dev2=(___) + (___) + (___) all over 2 =__ + __+ __ St. Dev=___ St.Dev of

### While keeping it at its melting point, you melt 526 g of ethanol ice. Compute the change of entropy of the ethanol.

While keeping it at its melting point, you melt 526 g of ethanol ice. Compute the change of entropy of the ethanol. (in J/K)

### heat evolved during combustion of hydrogen with oxygen

The combustion of hydrogen-oxygen mixtures is used to produce very high temperatures (about 2500 degrees Celsius) needed for certain types of welding. Consider the combustion reaction to be that shown below: H2 (g) + 1/2 O2 (g) ----> H2O (g) Change in Heat (Delta H) = -241.8 kJ How much heat is evolved when a

### heat evolved in the reaction of CaC2 with water

Calcium carbide (CaC2) reacts with water to form acetylene (C2H2), a gas used as a fuel in welding. CaC2 (s) + 2 H2O (l) ---> C2H2 (g) + Ca(OH)2 (s) Change in Heat (Delta H) = -128.0 kJ How many kilojoules of heat are evolved in the reaction of 3.5 kg CaC2 with 1.15 L H2O?

### Work Done on the System

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

### Swimming Pool - Cooler or Hotter

It is summer time, and you are in the pool. The air is much warmer than the pool water, but yet when you get out of the water into the warmer air, you feel cold! Explain why you feel cold, even though the air around you is warmer than the pool water you just got out of.

### Boiling an egg at an altitude

Explain why it takes longer to prepare a boiled egg at a very high altitude.

### Calculate the heat of dissolution (q) of urea using the following formula

Lab Questions: 1. Calculate the heat of dissolution (q) of urea using the following formula: q = -s m? Where is the heat capacity (assume the heat capacity is equivalent to the heat capacity of water: 4.184 J g-l degrees C-1, m is the mass of the solution and ?T is the change in temperature. 2. Calculate the molar enthalp

### 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

### Thermodynamics: Enthalpy and Entropy

1. Given that a formation of a bond between two atoms is exothermic and accompanied by an entropy decrease, explain why all chemical compounds decompose into individual atoms if heated to a high enough temperature. 2. Is the dissolution of urea driven by enthalpy or entropy? How do you know this? Give one example of each of a

### 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 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?

### 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

### 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

### Vapor Pressure of Ethanol in a 40% Alcoholic Beverage

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)

### 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 vaporize water

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

### Heat Required to Convert Water to Vapour

How many kilojoules of heat are required to convert 34.3 g H2O from liquid at 18.0 degrees Celsius to vapor at 32.8 degrees Celsius?

### 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

### 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