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Liquid hydrazine ( \(\mathrm{SG}=0.82\) ) undergoes a family of decomposition reactions that can be represented by the stoichiometric expression $$3 \mathrm{N}_{2} \mathrm{H}_{4} \rightarrow 6 x \mathrm{H}_{2}+(1+2 x) \mathrm{N}_{2}+(4-4 x) \mathrm{NH}_{3}$$ (a) For what range of values of \(x\) is this equation physically meaningful? (b) Plot the volume of product gas \([V(\mathrm{L})]\) at \(600^{\circ} \mathrm{C}\) and 10.0 bar absolute that would be formed from 50.0 liters of liquid hydrazine as a function of \(x,\) covering the range of \(x\) values determined in Part (b). (c) Speculate on what makes hydrazine a good propellant.

Short Answer

Expert verified
The range for \(x\) for the given stoichiometric expression to be physically meaningful is between 0 and 1. The volume of product gas formed from 50.0 liters of liquid hydrazine at \(600^{\circ} C\) and 10.0 bar depends on \(x\) and can be calculated using the ideal gas law. Hydrazine is a good propellant mainly due to its highly reactive nature and ability to form large volumes of gas rapidly and exothermically during decompositions.

Step by step solution

01

Determine the Range of x

For the stoichiometric expression of hydrazine decomposition to be physically meaningful, the coefficients of \(H_2\), \(N_2\), and \(NH_3\) must be non-negative. From the expression, we have:\n\[3 N_2 H_4 → 6x H_2 + (1+2x) N_2 + (4-4x) NH_3\]For the equation to be meaningful, \(6x \geq 0\), \((1+2x) \geq 0\), and \((4-4x) \geq 0\). Solving these inequalities, we obtain the value of \(x\) to be within the range of 0 and 1.
02

Calculate Volume of Product Gas

Next, using the ideal gas law \(PV = nRT\), we can find out the volume of product gas.\nFirstly, calculate the number of moles of hydrazine used using its specific gravity and the volume of liquid hydrazine. Then, substitute the number of moles of hydrazine into the stoichiometric expression for each product. This will give the total number of moles of products, which can be substituted back into the ideal gas equation to calculate the volume of product gas.
03

Identify the Properties of a Good Propellant

Finally, for c), it can be stated that hydrazine is a good propellant because it is highly reactive and decomposes to form large volumes of gas, which can provide significant thrust. Furthermore, the reaction is exothermic, meaning it releases heat, which can also contribute to the thrust.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Stoichiometry
Stoichiometry is a fundamental concept in chemistry that deals with the quantitative relationship between reactants and products in a chemical reaction. It's like a recipe for chemical reactions, helping us understand how much of each substance is needed or produced. In the case of hydrazine (\( \mathrm{N}_2\mathrm{H}_4 \)), its decomposition involves multiple products: hydrogen gas (\( \mathrm{H}_2 \)), nitrogen gas (\( \mathrm{N}_2 \)), and ammonia (\( \mathrm{NH}_3 \)). These reactions are represented using a balanced chemical equation which ensures that the atom count for each element is the same on both sides.
To keep the stoichiometry equation meaningful, the coefficients must remain non-negative. This means the number of all products should be zero or greater. Through algebraic balancing, we determine the range for the variable \(x\) in the given equation must be between 0 and 1, ensuring a realistic production of gases.
  • A stoichiometric coefficient gives the number of molecules or moles involved in a reaction.
  • Using stoichiometric ratios, one can predict the quantities of reactants and products.
Ideal Gas Law
The Ideal Gas Law is a critical tool in chemistry and physics, enabling us to relate the pressure, volume, temperature, and number of moles of a gas. This law is expressed by the formula \( PV = nRT \), where:
  • \(P\) is the pressure of the gas.
  • \(V\) is the volume of the gas.
  • \(n\) is the number of moles.
  • \(R\) is the ideal gas constant.
  • \(T\) is the temperature in Kelvin.
To solve the problem at hand, we use this formula to calculate the volume of gas products formed from liquid hydrazine. First, we convert the specific gravity and volume of hydrazine into moles. Then, applying the stoichiometric ratios, we determine the total moles of gaseous products generated. These moles are substituted into the Ideal Gas Law equation to find the gas volume at specified conditions of temperature and pressure.
This relationship helps to examine the behavior of gases in different scenarios.
Propellants
Propellants are materials that produce thrust by expelling mass at high speed. Hydrazine is an excellent propellant primarily because of its energetic decomposition reactions. Upon decomposition, it forms significant amounts of gas very quickly, which creates a powerful thrust.
The reasons hydrazine makes a good propellant include:
  • High reactivity: Rapidly decomposes, efficiently converting chemical energy to kinetic energy.
  • High gas production: Generates a large volume of gases, like \( \mathrm{H}_2 \) and\( \mathrm{N}_2 \) , contributing to strong propulsion.
  • Exothermic reaction: Releases heat, enhancing the energy delivered for propulsion.
Hydrazine's properties are utilized in various applications, especially in the aerospace industry for rocket fuels and thrusters, emphasizing the importance of understanding its chemical reactions and behavior.
Specific Gravity
Specific gravity (SG) is a dimensionless quantity that compares the density of a substance to the density of water. The SG of a substance provides insight into how dense it is compared to water. For instance, liquid hydrazine has a specific gravity of 0.82, indicating it is less dense than water.
  • SG = Density of substance / Density of water
Specific gravity is crucial when dealing with solutions and for converting volumes to masses or vice versa. In this exercise, it helps to determine the mass of hydrazine from its given volume. Once the mass is known, it can be converted into moles, forming the basis for further stoichiometric calculations.
Understanding specific gravity is essential in practical applications such as engineering and chemistry, where quick conversions between volume and mass are often necessary.

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Most popular questions from this chapter

An adult takes about 12 breaths per minute, inhaling roughly \(500 \mathrm{mL}\) of air with each breath. The molar compositions of the inspired and expired gases are as follows: $$\begin{array}{lcc} \hline \text { Species } & \text { Inspired Gas (\%) } & \text { Expired Gas (\%) } \\ \hline \mathrm{O}_{2} & 20.6 & 15.1 \\ \mathrm{CO}_{2} & 0.0 & 3.7 \\ \mathrm{N}_{2} & 77.4 & 75.0 \\ \mathrm{H}_{2} \mathrm{O} & 2.0 & 6.2 \\ \hline \end{array}$$ The inspired gas is at \(24^{\circ} \mathrm{C}\) and 1 atm, and the expired gas is at body temperature and pressure \(\left(37^{\circ} \mathrm{C}\right.\) and 1 atm). Nitrogen is not transported into or out of the blood in the lungs, so that \(\left(\mathrm{N}_{2}\right)_{\text {in }}=\left(\mathrm{N}_{2}\right)_{\text {out }}\) (a) Calculate the masses of \(\mathrm{O}_{2}, \mathrm{CO}_{2},\) and \(\mathrm{H}_{2} \mathrm{O}\) transferred from the pulmonary gases to the blood or vice versa (specify which) per minute. (b) Calculate the volume of air exhaled per milliliter inhaled. (c) At what rate (g/min) is this individual losing weight by merely breathing? (d) The rate at which oxygen is transferred from the air in the lungs to the blood is roughly proportional to \(\left[\left(p_{\mathrm{O}_{2}}\right)_{\mathrm{air}}-\left(p_{\mathrm{O}_{2}}\right)_{\mathrm{blood}}\right],\) where \(\left(p_{\mathrm{O}_{2}}\right)_{\mathrm{blood}}\) is a quantity related to the concentration of oxygen in the blood. Compared to regions where atmospheric pressure is 14.7 psia, what effect does the atmospheric pressure in Denver, which is approximately 12.1 psi, have on the transport rate and breathing rate? How does the body adjust to address this condition?

The flow rate required to yield a specified reading on an orifice meter varies inversely as the square root of the fluid density; that is, if a fluid with density \(\rho_{1}\left(g / \mathrm{cm}^{3}\right)\) flowing at a rate \(\dot{V}_{1}\left(\mathrm{cm}^{3} / \mathrm{s}\right)\) yields a meter reading \(\phi\), then the flow rate of a fluid with density \(\rho_{2}\) required to yield the same reading is $$\dot{V}_{2}=\dot{V}_{1}\left(\rho_{1} / \rho_{2}\right)^{1 / 2}$$ (a) An orifice meter has been calibrated with nitrogen at \(25^{\circ} \mathrm{C}\) and \(758 \mathrm{mm}\) Hg, but it now has methane flowing through it at \(50^{\circ} \mathrm{C}\) and \(1800 \mathrm{mm}\) Hg. Applying the nitrogen calibration to the reading indicates that the flow rate is \(21 \mathrm{L} / \mathrm{min}\). Estimate the true volumetric flow rate of the methane. (b) Repeat Part (a) but suppose the stream contains 10.0 mole \(\% \mathrm{CO}_{2}\) and 5.0 mole \(\%\) cthane in addition to methane.

A nitrogen rotameter is calibrated by feeding \(\mathrm{N}_{2}\) from a compressor through a pressure regulator, a needle valve, the rotameter, and a dry test meter, a device that measures the total volume of gas that passes through it. A water manometer is used to measure the gas pressure at the rotameter outlet. A flow rate is set using the needle valve, the rotameter reading, \(\phi\), is noted, and the change in the dry gas meter reading \((\Delta V)\) for a measured running time \((\Delta t)\) is recorded. The following calibration data are taken on a day when the temperature is \(23^{\circ} \mathrm{C}\) and barometric pressure is \(763 \mathrm{mm} \mathrm{Hg} .\) $$\begin{array}{rrr} \hline \phi & \Delta t(\min ) & \Delta V(\mathrm{L}) \\ \hline 5.0 & 10.0 & 1.50 \\ 9.0 & 10.0 & 2.90 \\ 12.0 & 5.0 & 2.00 \\ \hline \end{array}$$ (a) Prepare a calibration chart of \(\phi\) versus \(\dot{V}_{\text {sid }}\), the flow rate in standard \(\mathrm{cm}^{3} / \mathrm{min}\) equivalent to the actual flow rate at the measurement conditions. (b) Suppose the rotameter-valve combination is to be used to set the flow rate to 0.010 mol \(\mathrm{N}_{2} / \mathrm{min}\). What rotameter reading must be maintained by adjusting the valve?

A process stream flowing at \(35 \mathrm{kmol} / \mathrm{h}\) contains 15 mole \(\%\) hydrogen and the remainder 1 -butene. The stream pressure is 10.0 atm absolute, the temperature is \(50^{\circ} \mathrm{C}\), and the velocity is \(150 \mathrm{m} / \mathrm{min}\). Determine the diameter (in \(\mathrm{cm}\) ) of the pipe transporting this stream, using Kay's rule in your calculations.

Oxygen therapy uses various devices to provide oxygen to patients having difficulty getting sufficient amounts from air through normal breathing. Among the devices is a nasal cannula, which transports oxygen through small plastic tubes from a supply tank to prongs placed in the nostril. Consider a specific configuration in which the supply tank, whose volume is \(6.0 \mathrm{ft}^{3},\) is filled to a pressure of 2100 psig at a temperature of \(85^{\circ} \mathrm{F}\). The paticnt is in an environment where the ambicnt temperature is \(40^{\circ} \mathrm{F}\). When the cannula is put into use, the pressure in the tank begins to decrease as oxygen flows at \(10-15 \mathrm{L} / \mathrm{min}\) through a tube and the cannula into the nostrils. (a) Estimate the original mass of oxygen in the tank using the compressibility-factor equation of state. (b) What is the initial pressure when the temperature is 40 \(^{\circ} \mathrm{F} ?\) How much oxygen remains in the tank when application of the ideal-gas equation of state produces a result that is within \(3 \%\) of that predicted by the compressibility-factor equation of state (i.e., when \(0.97 \leq z \leq 1.03\) )? (c) How long will it take for the gauge on the tank to read 50 psig, assuming an average flow rate of \(12.5 \mathrm{L} / \mathrm{min} ?\)

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