The behaviour is governed by the ratio of back pressure pback to total pressure p0. For pressures above psub the flow remains subsonic throughout. For pressures below psub the flow goes supersonic at the throat; the throat is choked and the maximum mass flow rate is achieved. At the design pressure pdesign the flow passes smoothly from subsonic to supersonic without shocks. To determine psub and pdesign, since A* = Athroat, use the subsonic and supersonic Mach numbers corresponding to isentropic flow with area ratio Aexit/Athroat: where Masub and Madesign are the subsonic and supersonic solutions, respectively, of Figure 1.
For one mole of gas, the difference between Cp and CV is the constant R (R is the so called universal gas constant) and represents the capacity of the gas to perform expansion work at constant applied pressure. {Cp = CV+R for an ideal gas} Since, for solids and liquids, the constant pressure and constant volume Heat Capacities are the same, the subscript p or V on the 'C' is usually dropped. Q = m C DT This means that the proportionality between the Heat flow into (or out of) an object and the Temperature change of that object is the total Heat Capacity, which can be expressed as a molar property or per mass. if m is moles and C is molar Heat Capacity if m is mass (grams) and C is the Specific Heat Q is positive for a temperature increase because the system has undergone an endothermic change of
Therefore, according to Hess’s law, the heat of reaction of the one reaction should be equal to the sum of the heats of reaction for the other two. This concept is sometimes referred to as the additivity of heats of reaction. The primary objective of this experiment is to confirm this law. The reactions we will use in this experiment are: 18 - 1 Computer 18 You will use a Styrofoam cup in a beaker as a calorimeter, as shown in Figure 1. For purposes of this experiment, you may assume that the heat loss to the calorimeter and the surrounding air is negligible.
Tammy Thanaporn Amornkasemwong 1st September 2011 Science Period 8 Introduction: How much energy can be released from fuels? Combustion is the process of burning fuel in order to produce heat. The intention of this experiment is to find whether different fuels produce different amount of energy. In the process of combustion in this experiment, cheeto, half a cashew nut, wax candle and ethanol are used as fuels combust with lighter, as heat and oxygen. When the fuels combust, oxygen and fuels react, and heat released.
Chapter 15 Chemical Equilibrium Section 1 * A chemical reaction can achieve a state in which the forward and reverse processes are occurring at the same rate. * This condition is called chemical equilibrium, and it results in the formation of an equilibrium mixture of the reactants and products of the reaction. * The composition of an equilibrium mixture does not change with time. * An equilibrium that is used throughout the chapter is the reaction of N2 with H2 to form NH3. * This reaction is the bases of the Haber process for the production of ammonia.
Calculations involving the Mole, Avogadro’s Number, Molar Mass, Mole-Mole and Mass-Mole calculations in chemical equations. Combustion analysis and calculation of empirical and molecular formulas from composition analysis. Electrolytes and non-electrolytes. Precipitation reactions and solubility rules. Writing balanced molecular equations and net ionic equations.
There are advantages and disadvantages to their use as fuels. Fuels can come from renewable or non-renewable resources. Subject Content Candidates should use their skills, knowledge and understanding to: ■ evaluate the impact on the environment of burning hydrocarbon fuels Additional guidance: Knowledge and understanding of the products of burning hydrocarbon fuels and the effects of these products is limited to those named in the subject content for this section. Candidates may be given information and data about other fuels and their products of combustion for comparison and evaluation in the examinations. Candidates should know and understand the benefits and disadvantages of ethanol and hydrogen as fuels in terms of: ■ ■ ■ ■ consider and evaluate the social, economic and environmental impacts of the uses of fuels 3
The main differences between diesel and gasoline are as follows: “a) A diesel Engine takes air into the cylinder and compresses it. Fuel is then injected directly into the cylinder. The heat of the compression lights the fuel spontaneously. A gasoline engine takes in a mixture of gas and air. The fuel and air are mixed outside of the cylinder; once they are both injected they require a spark to ignite.
The thermodynamic free energy is the amount of work that a thermodynamic system can perform. The concept is useful in the thermodynamics of chemical or thermal processes in engineering and science. The free energy is the internal energy of a system minus the amount of energy that cannot be used to perform work. This unusable energy is given by the entropy of a system multiplied by the temperature of the system. Like the internal energy, the free energy is a thermodynamic state function.
It expands when its temperature rises above 4° C. (39° F.). It also expands when it freezes. Expansion of Gases Under equal pressures, all gases expand at the same rate. A gas expands by the same proportion as the temperature rises, provided external pressure remains the same. The effect of heat on the expansion of gases is stated in Charles' Law.