Nitrogen mole relationships

This balanced equation can be read as 1 nitrogen molecule reacts with 3 hydrogen molecules to produce 2 ammonia molecules. But as indicated previously, the coefficients can stand not only for the number of atoms or molecules (microscopic level), they can also stand for the number of moles of reactants or products. The equation can also be read as 1 mol of nitrogen molecules reacts with 3 mol of hydrogen molecules to produce 2 mol of ammonia molecules. And if the number of moles is known, the number of grams or molecules can be calculated. This is stoichiometry, the calculation of the amount (mass, moles, particles) of one substance in a chemical reaction through the use of another. The coefficients in a balanced chemical equation define the mathematical relationship between the reactants and products, and allow the conversion from moles of one chemical species in the reaction to another. 

It is not necessary to find the weight of calcium nitrate containing 20.0 g N. The relationship between the calcium and the nitrogen can be found directly from the formula. There are 2 atoms of nitrogen for each atom of calcium. This relationship can also be expressed in terms of moles 2mol N 1 mol Ca. 

So the chemical equation N2(g) + 3H2(g) -> 2NH3(g) also means that 1 mol of nitrogen molecules reacts with 3 mol of hydrogen molecules to form 2 mol of ammonia molecules. The relationships between moles in a balanced chemical equation are called mole ratios. For example, the mole ratio of nitrogen to hydrogen in the equation above is 1 mol N2 3 mol H2. The mole ratio of hydrogen to ammonia is 3 mol H2 2 mol NH3. 

The design engineer (a) converts the volumetric flow rate of the feed stream to a molar flow rate using the ideal gas equation of state, an approximate relationship between the pressure, temperature, volumetric flow rate, and molar flow rate of a gas (Chapter 5) (b) specifies a condenser temperature of IS C (c) calculates the mole fraction of MEK in the vapor product using Raoult s law—an approximate relationship between the compositions of liquid and vapor phases in equilibrium with each other at a specified temperature and pressure (Chapter 6) and (d) calculates the molar flow rates of the vapor and liquid products from nitrogen and MEK balances (input = output). The results follow. 

The rate-determining step is(1.2b) nitrogen adsorption, which requires an activation energy of only I2kcal mole. Rates accelerate enormously, by a factor of 10 at 300"C. Notice that initial and final enthalpies are unchanged, so that equilibrium conversion X,. is the same. Conversions follow the relationships shown in Fig. 1.2. 

By definition, the atomic mass of the carbon-12 atom is exactly 12.00 amu. One mole of carbon-12 atoms has a mass of exactly 12.00 g, and that 12.00 g mass contains exactly 6.022 x 1023 carbon-12 atoms. This statement sets the benchmark for all chemical calculations involving the mole. One mole of any element is an amount of that element equal to its atomic mass in grams (its molar mass), and that mass contains 6.022 x 1023 atoms of that element. Using atomic masses, you can apply these relationships to the elements hydrogen and nitrogen. 

If the displacer motions are considered to be sinusoidal and phase-separated by 90 , it is evident that the room-temperature volume at any instant of time is i(F//)(l — cos 6) at temperature Th the cold-end volume is i(Vc)(l — sin 9) at temperature Tc the liquid-nitrogen-temperature volume is Vh) + cos 0) 4- Vc) + sin 0) at temperature T/ and all other void volumes are Vv at temperature Tv. In these relationships Vh is the swept volume at the hot end, Fc is the swept volume at the cold end, Vv is the volume of the rest of the system (void volume), Th is the hot-end temperature, Tc is the cold-end temperature, T/ is the temperature between displacers, Tk is the effective temperature of the void volumes, n is the total number of moles of gas in the system, p is the instantaneous pressure throughout the system, 6 is the portion of the cycle completed, starting from the time when the volume of the hot end is at a minimum, R is the universal gas constant Qc is the area of the cold-end indicator diagram for one cycle, and Qh is the area of the hot-end indicator diagram for one cycle. If ideality of gas is assumed,... 

The appropriate flow diagram is shown in figure 2.7. The product stream (stream 5) contains 1 per cent of the nitrogen in stream 3. The amount of nitrogen in stream 3 is 85 per cent of that in stream 2 (the rest is converted to ammonia). If the basis of the calculation is 100 moles of feed, the relationships can be symbolically represented by... 

The main conversion factors come from the stoichiometric relationship between moles of each reactant and moles of ammonia. The other conversion factors are the molar masses of nitrogen monoxide, hydrogen gas, and ammonia. 

The correct dew-point temperature is located when this relationship equals 0.5, the mole fraction of the nitrogen in the mixture. At a temperature of 103.60 K, the relation is satisfied as noted below ... 

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