Introduction: In this lab there were several purposes. Each purpose was to help further the class’s understanding of thermodynamics. Thermodynamics studies the changes in chemical and physical reactions and how energy influences those changes. The purposes of the lab were to decided which of the four given substances would make a good hot pack or cold back, to be able to design a hot pack and cold pack for specified temperature changes, to calculate the amount of heat released or absorbed by one gram of calcium chloride or ammonium nitrate, and to calculate the percentage error in the experiment. In order to understand the lab one must also understand endothermic and exothermic reactions.
The study of specific heat falls under the category of Thermochemistry which is further divided into the category of Calorimetry. An instrument called a calorimeter is used to measure specific heat. A piece of metal is placed in a container of water. This is then boiled. The piece of metal is then taken out of the boiling water and placed in a calorimeter which contains room temperature water.
What did Boyle’s experiments convince him about cold? That heat is a form of motion of a particular kind as bodies cool down the particles move less and less 5. How did Boyle explain that substances expand when they warm up? He thought back to his air experiments, and explained that the particles have spring like coils that expand as they heat 6. Describe the earliest alcohol thermometers.
Dr Khounsary explains an experiment using a fixed voltage and varying the temperature of the wire using a torch. The article further explains that the temperature coefficient of copper at 20 degrees C is .00393 and that a single degree of temperature change would increase the resistance of the wire by that amount. In the article regarding the Effect of Temperature on Conductivity (The Nuffield Foundation, 2006) the article describes how the conductivity of a wire decreases as it is heated. It provides an example schematic diagram for the test circuit and the use of Eureka wire instead of copper wire. A2a.
Different compounds boil at different temperatures because each has a different, characteristic vapor pressure: compounds with higher vapor pressures will boil at lower temperatures. Boiling points are usually measured by recording the boiling point (or boiling range) on a thermometer while performing a distillation. This method is used whenever there is enough of the compound to perform a distillation. The distillation method of
(Nitrogen, hydrogen, oxygen, carbon dioxide, and other elements cause weld defects if introduced to the weld pool.) After a while it was discovered that argon has some advantages over helium. Because argon is heavier than helium, less flow rate is needed. The lower flow rate requirement makes argon better for flat welding. Helium is good for overhead, because it is lighter and thus flows upward.
The melting point ranges of the impure and pure benzoic acid seemed reasonable. The difference between the literature melting point values of the pure Benzoic acid 21.5-22.5 is different than the one determined in the experiment. The recrystallization was experimentally showed as an inaccurate purification method. Introduction: Recrystallization is the purification technique in which a solid slowly forms, crystallize, from a liquid solution. It is based on the manipulation of the solubility at various temperatures.
HSC Chemistry Assessment task 1 Nuclear Chemistry Research report 1. Distinguish between stable and radioactive isotopes and describe the conditions which a nucleus is unstable. To understand if an element is stable we first must understand what stability is. The stability of the nucleus is directly related to the strength of the forces that hold the nuclear particles together. These protons and neutrons of the nucleus are called nucleons.
A hypothesis for the experiment states that solutions with charged particles are going to conduct an electrical charge whereas solutions with molecular particles will not. There may be a direct correlation between the number of charged particles and the conductivity of the solution. Results Table 1 Substance | Conductivity (μs/cm) | TDS (mg/L) | Sodium chloride (NaCl) | 5432 | 3259.2 | Calcium chloride (CaCl2) | 9127 | 5476.2 | Methanol (CH4O) | 19.09 | 11.454 | Ethanol (C2H6O) | 19.09 | 11.454 | Sucrose (C12H22O12) | 19.09 | 11.454 | Glucose (C6H12O6) | 19.55 | 11.73 | Freshwater | 2826 | 1695.6 | Saltwater | 13800 | 8280 | Tap water | 429.6 | 257.76 | Bottled water | 19.09 | 11.454 | Distilled water | 19.09 | 11.454 | Sports drink | 2855 | 1713 | Figure 1 Table 2 Substance | Conductivity (μs/cm) | TDS (mg/L) | Methanol | 19.09 | 11.454 | Ethanol | 19.09 | 11.454 | Sucrose | 19.09 | 11.454 | Glucose | 19.55 | 11.73 | Tap water | 429.6 | 257.76 | Bottled water | 19.09 | 11.454 | Distilled water | 19.09 | 11.454 | Figure 2 Discussion and conclusion Checking for the presence of charged particles can test solution purity. Particles, in relation to this experiment, come in two forms: molecular and ionic. Molecular compounds are ones, which have shared electrons between the atoms and do not carry an overall charge for the molecule.
This makes the temperature of the fluid in the system to change, and so does the temperature of the dividing walls between the two fluids. Examples of heat exchangers are; intercoolers, preheaters, oil coolers of heat engine, condensers, and evaporators in refrigeration units (Harriman 289). Various types of heat exchangers have been developed to meet the widely varying applications and are classified according to; nature of heat exchange process, physical state of fluid, constructional and design specs and relative direction of fluid flow. According to the nature of the heat exchange process, heat exchangers are classified as; direct and indirect contact heat exchangers. Plate and shell heat exchanger, combines both the plate heat exchangers and the shell exchangers for maximum efficiency.