For the following reactions determine the maximum or

Question

Part A -

Q1. a) Use the group contribution method to estimate the normal melting point and the standard heat of formation at 298^oK (H_f) of 1, 9 nonanediol.

b) Find the normal melting point and the standard heat of formation at 298^oK of 1, 9-nonadiol in AspenPlus using the NRTL equation of state. (1, 9- Dihydroxynonane in the NISTV88 Database).

Q2. Complete exercise (a) and (b) in the text.

For part (a): The objective is to calculate the mass of anhydrous salt and the mass of water that would be placed in the bag (before crystallization) for each of the four candidate salts. Assume that, upon the completion of crystallization at 40^oC, each of the salts has the capacity to add 100g of water in addition to the equilibrium solubility of the salt (you will not need to use the supersaturation of 2 given in the problem statement) and that there is no heat lost during the process. (Hint: First calculate how much of each of the hydrated salts is required by energy balance. For that energy balance, the heat released from salt crystallization must equal the heat gained by the entire solution, i.e., the hydrated salt, the additional 100 g of water and the non-hydrated salt that dissolves into that 100 g of water. After you've determined the amount of hydrated salt required, you can then calculate the amount of each solid, non-hydrated, salt that you will need for the bag and the total amount of water.)

For part (b): To calculate the required dimensions, assume that the bag should be square in surface and fit a typical hand that is 8cm x 8cm. Assume densities are constant over the range of 20^oC to 40^oC (see Table). To calculate the amount of heat available, assume that the hand temperature is 32^oC, so the available heat is that which is transferred from 32^oC to 40^oC.

Material	Density
NaC2H3O2	1.52
NaS2O3	1.67
Ca(NO3)2	2.50
Pb(C2H3O2)2	3.25
Water	1.00

Q3. a) Use Aspen Plus to determine the flow rate of saturated vapor benzene at 176.2^oF and 1 atm to be mixed with 100 Ibmol/hr of liquid benzene to raise its temperature from 25^oF to 50^oF. For convergence, you will need a reasonable first guess at the flow rate (ΔH_v = 13200 BTU/lbmol and c_p = 0.42 BTU/lb^oF).

b) Create a plot of vapor benzene flow rate (lb mol/hr) vs. mixer discharge temperature(^oF).

Q4. a)Use Aspen Plus to determine the heat required to vaporize 45 mol% of a liquid stream entering an evaporator (heater) at 150^oF and 202 psia and containing:

	Lbmol/hr
Propane	250
n-Butane	400
n-Pentane	350

Assume the evaporator product is at 200 psia.

b) Generate a plot of heat input to the evaporator vs. exit quality (mol fraction vapor between 0 and 1).

Use RK-Soave EOS for both of these problems.                                

Q5. A simplified flowsheet for the "Cavett Problem" is shown below:

a) Use Aspen Plus to determine the component flow rates and conditions for all streams in the process.

b) At what temperature in the top stage will the n-butane flow in the overhead be less than 100 lb mol/hr? (all other conditions are as shown)

c) Plot the pressure in the top stage (F1) from 280 to 1200 psia vs. the mole fractions of propane, isobutane and n-butane in the overhead. (temp=100^oF).

Use RK-Soave EOS.

Part B -

Question - A healthcare company decides to market a hand warmer. It is basically a palm-size plastic pouch containing a supersaturated aqueous salt solution: that is, the amount of dissolved salt exceeds its solubility limit. The degree of supersaturation is the ratio of the mass of dissolved salt per unit mass of water to the mass of salt at saturation: it is expected to be in the range of 1 to 2. By flexing a small metal disk in the solution, the salt begins to crystallize, and the heat of crystallization produces a temperature rise rapidly. The amount of heat is sufficient to keep the hands holding the pouch warm over a period of up to 30 min. This hand warmer can be recharged by redissolving the salt in a microwave oven or in hot water.

From the patent literature, four potential candidates can be identified: sodium acetate, sodium thiosulfate, calcium nitrate, and lead acetate. These are all hydrated at ambient temperatures with high solubility and relatively high heats of crystallization (Mullin. 1993).

Salt	Heat of Crystallization at ∼ 20oC (kcal/mol)	Equilibrium Solubility at 20oC (g anhyd./100 g Water)	Equilibrium Solubility at 40oC (g anhyd./100 g Water)
NaC2H3O2·3H2O	-4.7	46.5	65.5
Na2S2O3·5H2O	-11.4	70	103
Ca(NO3)2·4H2O	-8.0	129	196
Pb(C2H3O2)2·3H2O	-5.9	44.1	116

Data for the specific heat of these salts are not readily available but can be estimated using Kopp's rule, which states that the heat capacity of a solid compound or the compound in liquid form is approximately equal to the sum of the heat capacities of the individual atoms. The following table shows values for individual atoms determined from experimental data.

Values of Atomic Heat Capacity at 20^oC [cal/(g atom)(*C)]

Element	Solids	Liquids
C	1.8	2.8
H	2.3	4.3
B	2.7	4.7
Si	3.8	5.8
O	4.0	6.0
F	5.0	7.0
P or S	5.4	7.4
All others	6.2	8.0

 (a) The product performance calls for a temperature rise from 21^oC to 40^oC. If all four salts can be assumed to be able to accommodate a supersaturation of up to around 2, select one and justify its use in the hand warmer product. [Hint: Perform energy balance to determine the required amount of salt in a supersaturated solution.]

(b) Determine the product specifications. Specifically, provide the dimensions of the pouch, the amount of salt and water within the pouch, and the amount of heat available for hand warming.

Part C -

Question - For the following reactions, determine the maximum or minimum temperatures of the reactor effluents assuming:

(a) Complete conversion

(b) Equilibrium conversion

The reactants are available in stoichiometric proportions at the temperature and pressure indicated.

	T0(oF)	P (atm)
a. C7H8 + H2 → C6H6 + CH4	1,200	38.7
b. SO2 + ½O2 → SO3	77	1.0
c. CO + ½O2 → CO2	77	1.0
d. C2H4Cl2 → C2H3Cl + HCl	932	26.0

 Also, find the heats of reaction at the conditions of the reactants.

Complete this Question (Aspen Plus simulations, ony). Use the RK-Soave EOS (Pure-10 Databank) and complete this table:

	T0(oF)	P (atm)	T100% (oF)	TEqual (oF)	ΔHreac (Btu/lbmol reactant)
C7H8 + H2 → C6H6 + CH4	1200	38.7
SO2 + ½O2 → SO3	77	1.0
CO + ½O2 → CO2	77	1.0
C2H4Cl2 → C2H3Cl + HCl	932	26.0