Q: The enthalpy change for the reaction of hydrogen gas with fluorine gas
The enthalpy change for the reaction of hydrogen gas with fluorine gas to produce hydrogen fluoride is 2542 kJ for the equation as written: H2(g) + F2(g) 2HF(g) ∆H = -542 kJ a. Wh...
See AnswerQ: The enthalpy change for a reaction that occurs at constant pressure is
The enthalpy change for a reaction that occurs at constant pressure is (higher than/lower than/the same as) the heat for that reaction.
See AnswerQ: Calculate the enthalpy change when 5.00 g of propane is
Calculate the enthalpy change when 5.00 g of propane is burned with excess oxygen according to the reaction C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) ∆H = -2221 kJ/mol
See AnswerQ: The enthalpy (∆H) of vaporization of water is about seven
The enthalpy (∆H) of vaporization of water is about seven times larger than water’s enthalpy of fusion (41 kJ/mol vs. 6 kJ/mol). What does this tell us about the relative similarities among the solid,...
See AnswerQ: What is the enthalpy change for a process? Is enthalpy a
What is the enthalpy change for a process? Is enthalpy a state function? In what experimental apparatus are enthalpy changes measured?
See AnswerQ: Hess’s law is often confusing to students. Imagine you are talking
Hess’s law is often confusing to students. Imagine you are talking to a friend who has not taken any science courses. Using the reactions P4(s) + 6Cl2(g) / 4PCl3(g) (H = 22.44 * 103 kJ 4PCl5(g) / P4...
See AnswerQ: A demethanizer tower is used in a refinery to separate natural gas
A demethanizer tower is used in a refinery to separate natural gas from a light hydrocarbon gas mixture stream (1) having the composition listed below. However, initial calculations show that there is...
See AnswerQ: For a particular isomer of C8H18, the following reaction produces 5093
For a particular isomer of C8H18, the following reaction produces 5093.7 kJ of heat per mole of C8H18(g) consumed, under standard conditions.
See AnswerQ: For a particular isomer of C8H18, the following reaction produces 5113
For a particular isomer of C8H18, the following reaction produces 5113.3 kJ of heat per mole of C8H18(g) consumed, under standard conditions. What is the standard enthalpy of formation of this isomer...
See AnswerQ: When benzene freezes at 5.5 C its density changes from
When benzene freezes at 5.5 C its density changes from 0.879 g/cm3 to 0.891 g/cm3. Its enthalpy of fusion is 10.59 kJmol-1. Estimate the freezing point of benzene at 1000 atm. The normal freezing poin...
See AnswerQ: The enthalpy When benzene freezes at 1 atm and at 5.
The enthalpy When benzene freezes at 1 atm and at 5.5°C its mass density changes from 0.879 g cm of fusion is 10.59 kJ/mol. Estimate the freezing point of benzene at 1,020 atm.
See AnswerQ: When benzene freezes at 5.5°C its density changes
When benzene freezes at 5.5°C its density changes from 0.879 gcm−3 to 0.891 gcm−3. Its enthalpy of fusion is 10.59 kJ mol−1. Estimate the freezing point of benzene at 1005 atm.
See AnswerQ: One pound-mass of water fills a container whose volume is
One pound-mass of water fills a container whose volume is 2 ft3. The pressure in the container is 100 psia. Calculate the total internal energy and enthalpy in the container.
See AnswerQ: A piston–cylinder device contains 0.85 kg of refrigerant
A piston–cylinder device contains 0.85 kg of refrigerant 134a at –10°C. The piston that is free to move has a mass of 12 kg and a diameter of 25 cm. The...
See AnswerQ: How much error would one expect in determining the specific enthalpy by
How much error would one expect in determining the specific enthalpy by applying the incompressible-liquid approximation to water at 3000 psia and 400°F?
See AnswerQ: 10 kg of R-134a at 300 kPa fills a rigid
10 kg of R-134a at 300 kPa fills a rigid container whose volume is 14 L. Determine the temperature and total enthalpy in the container. The container is now heated until the pressure is 600 kPa. Deter...
See AnswerQ: A piston–cylinder device initially contains 50 L of liquid water
A piston–cylinder device initially contains 50 L of liquid water at 40°C and 200 kPa. Heat is transferred to the water at constant pressure until all liquid is vaporized. (a) What is the mass of the w...
See AnswerQ: The spring-loaded piston–cylinder device shown in Fig.
The spring-loaded piston–cylinder device shown in Fig. P4–62 is filled with 0.5 kg of water vapor that is initially at 4 MPa and 400°C. Initially, the sp...
See AnswerQ: A piston–cylinder device initially contains steam at 3.5
A piston–cylinder device initially contains steam at 3.5 MPa, superheated by 5°C. Now, steam loses heat to the surroundings and the piston moves down, hitting a set of sto...
See AnswerQ: Neon is compressed from 100 kPa and 20°C to 500
Neon is compressed from 100 kPa and 20°C to 500 kPa in an isothermal compressor. Determine the change in the specific volume and specific enthalpy of neon caused by this compression.
See AnswerQ: What is the change in the enthalpy, in kJ/kg
What is the change in the enthalpy, in kJ/kg, of oxygen as its temperature changes from 150 to 250°C? Is there any difference if the temperature change were from 0 to 100°C? Does the pressure at the b...
See AnswerQ: A mass of 10 g of nitrogen is contained in the spring
A mass of 10 g of nitrogen is contained in the spring loaded piston–cylinder device shown in Fig. P5–51. The spring constant is 1 kN/m, and the piston diameter is 1...
See AnswerQ: Determine the enthalpy change Δh of oxygen, in Btu/lbm
Determine the enthalpy change Δh of oxygen, in Btu/lbm, as it is heated from 800 to 1500 R, using (a) the empirical specific heat equation as a function of temperature, (b) the cp value at the average...
See AnswerQ: The state of liquid water is changed from 50 psia and 50
The state of liquid water is changed from 50 psia and 50°F to 2000 psia and 100°F. Determine the change in the internal energy and enthalpy of water on the basis of the (a) compressed liquid tables, (...
See AnswerQ: A liquid R-134a bottle has an internal volume of 0
A liquid R-134a bottle has an internal volume of 0.0015 m3. Initially it contains 0.55 kg of R-134a (saturated mixture) at 26°C. A valve is opened and R-134a vapor only (no liquid) is allowed to escap...
See AnswerQ: Refrigerant-134a at 700 kPa and 40°C is expanded
Refrigerant-134a at 700 kPa and 40°C is expanded adiabatically in a closed system to 60 kPa. Determine the work produced, in kJ/kg, and final enthalpy for an isentropic expansion efficiency of 80 perc...
See AnswerQ: R-134a vapor enters into a turbine at 250 psia and
R-134a vapor enters into a turbine at 250 psia and 175°F. The temperature of R-134a is reduced to 20°F in this turbine while its specific entropy remains constant. Determine the...
See AnswerQ: Water vapor enters a compressor at 35 kPa and 160°C
Water vapor enters a compressor at 35 kPa and 160°C and leaves at 300 kPa with the same specific entropy as at the inlet. What are the temperature and the specific enthalpy of water at the...
See AnswerQ: Some properties of ideal gases such as internal energy and enthalpy vary
Some properties of ideal gases such as internal energy and enthalpy vary with temperature only [that is, u = u(T) and h = h(T)]. Is this also the case for entropy?
See AnswerQ: The entropy of steam increases in actual steam turbines as a result
The entropy of steam increases in actual steam turbines as a result of irreversibility. In an effort to control entropy increase, it is proposed to cool the steam in the turbine by running cooling wat...
See AnswerQ: Consider a point in a flow where the velocity and temperature are
Consider a point in a flow where the velocity and temperature are 1300 ft/s and 480 ◦R, respectively. Calculate the total enthalpy at this point.
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