Chemical reactions transform bond energy into heat or work. Enthalpy of reaction (Hrxn) is the term used for the change in heat as a reaction is carried out at constant pressure. It is a state function as it only depends on the final and initial conditions during the change of state. If Hrxn < 0, the system releases heat and is therefore an exothermic reaction. On the other hand, if Hrxn > 0, the system absorbs heat.
Introduction Heat is the form of energy, thermal energy, which flows between two substances due to their difference in temperature.1 The measurement of heat flow is called Calorimetry and the apparatus used to measure the heat flow (temperature change) for a reacting system is called a calorimeter. The calorimeter is well-insulated device that help to minimize the heat exchange between the system being observed and its surroundings. In this experiment, simple calorimeter, coffer cup calorimeter containing Styrofoam cups is used. Calorimeter contains a thermometer and a stirrer.3 Thermometer is typically inserted in the calorimeter to measure the change in the temperature that results from the reaction. Stirrer is used to keep the contents
Furthermore, the confinement time, which is a measure of how quickly power is lost to the environment is given by τ_E=W/P_loss where W is the energy density and Ploss is the energy loss rate per unit volume (Lawson, J. “Some”). Finally, by taking the volume rate, which is a function of the number of reactions per volume per time, and multiplying by the charge of the particles, we get a quantity that we know must be greater than the power loss, per the initial criterion (Lawson, J. “Some Criteria for a Useful”). Doing some algebra, we can then reduce to the expression 〖nτ〗_E≥L T/σv where L is a constant, T is the temperature of the system, σ is the nuclear cross section, or chance that two particles have to collide, and v is the relative velocity of the two particles.
I. Introduction This experiment uses calorimetry to measure the specific heat of a metal. Calorimetry is used to observe and measure heat flow between two substances. The heat flow is measured as it travels from a higher temperature to a lower one. Specific heat is an amount of heat required to raise the temperature of one gram of anything one degree Celsius.
Ohms are measured in Ω, or omega. Voltage is measured in volts, or v. Current is measured in amps, or I. Resistance is measured in ohms, or r. For pipes, voltage would be like the water pressure, current would be like the flow rate, and the resistance would be like the pipe size. The equation to measure voltage is V=IR.A variant of this, Ohm’s law, for measuring resistance, has this
The proportionality constant, R, is known as the resistance and is determined by both material properties (the intrinsic resistivity) and geometry (length and cross-sectional area of the active material). In equation form, Ohm’s law is: V = IR. It is important to understand just what is meant by these quantities. The current (I) is a measure of how many electrons are flowing past a given point during a set amount of time. The current flows because of the electric potential (V), sometimes referred to as the voltage, applied to a circuit.
Observation/ Research: Boyle’s Law As Robert Boyle stated “Pressure and Volume are inversely related. To add more, temperature and moles are constant.” (Boyle). So, if Pressure increases, then the volume decreases or the other way around. This is Boyle’s Law. According to this law, P x V = k, where k is a constant.
We were asked to graph pressure and the inverse of volume because the graph of pressure and inverse volume is inversely related to the graph of pressure and volume. The graph allows a visual representation of what being inversely related conveys. The mathematical relationship that exists between volume and temperature when pressure and quantity are held constant is that volume is directly proportional to temperature. This relationship is known as Charles 's Law. (V1 / T1) = (V2 / T2).
FEA Treatment of Thermal Modeling The basis for thermal analysis in ANSYS is a heat balance equation obtained from the principle of conservation of energy. The finite element solution performed via Mechanical APDL calculates nodal temperatures, and then uses the nodal temperatures to obtain other thermal quantities. The ANSYS program handles all three primary modes of heat transfer: conduction, convection, and radiation. Mesh was created in Ansys. The mesh had 144005 elements.
The etchant used in this experiment is Ferric Chloride. Optimized parameters are Undercut, Etch factor & Material Removal Rate. This parameter optimized by varying factors affecting on process are Temperature, Concentration & Time. An optimal parameters combination for the maximum material Removal Rate, Etch factor & minimum undercut within the range of selected control parameters were obtained by using Analysis of Variance (ANOVA) & F-test. It was observed that, the Optimal parameters for the maximum material removal rate, etch factor & undercut is at etchant temp.