Chapter 6 DIFFUSION IN SOLIDS • How does diffusion occur? • Why is it an important part of processing? • How can the rate of diffusion be predicted for some simple cases? • How does diffusion depend on structure and temperature? Driving force for movement In general‚ force is a position derivative of energy (F = - dE/dr). In other words‚ if there is any energy difference in space‚ there is a force which will act on matters - Force will move things. (ex1) Potential energy by gravity:
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constant random motion Kinetic energy is transferred between particles as they collide Pressure The force exerted per unit of area Formula: pressure/force area Measured by barometer A vacuum is empty space‚ with no particles or pressure. Atmospheric pressure is the collision air particles with objects Units of pressure Kilopascals (kPa) Atmospheres (atm) Millimeters of mercury (mmHg) Temperature What happens to the motion of gas molecules if the gas is heated? As a gas is heated‚ the
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Have you ever seen dry ice‚ well let me show you. To measure the evaporation rate it is important to know that a half pound of dry ice will be placed outside and timed. The same thing will happen but in a cool room. If the dry ice is -109.3°F then it will evaporate in any condition warmer. The hypotheses is that the dry ice in the outside will evaporation faster. It is important to understand this because if you are trying to store dry ice and you put it in a freezer it will still evaporate. So in
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cock C4 off its seat to equalize the pressure inside burette B with the ambient pressure. Then raise bottle L gently until water level in the burette coincides with the zero mark. This ensures that the burette now contains 100 ml of exhaust gas at atmospheric pressure.
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condensation rate are equal. The liquid and vapor reach a state of dynamic equilibrium: liquid molecules evaporate and vapor molecules condense at the same rate. The boiling point of a liquid is the temperature at which its vapor pressure equals atmospheric pressure. While a gas is forming‚ the vapor pressure within the gas bubbles equals the external pressure. However‚ if the vapor pressure does not equal the external pressure‚ the bubble may burst or corrupt. If the vapor pressure within a bubble
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THERMOELECTRIC POWERED CAR 1. AIM OF THE PROJECT This concept behind the project is thermoelectric generation that has been known from sometime‚ but the practical implementation of this concept is quite difficult. The idea behind this project is to make a Car that is powered by thermoelectric source‚ i.e. to build a car that moves with temperature difference. This concept has not been explored earlier but a lot of research can be done in this regard. We will be presenting a practically running
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Unit 004: Understand how to apply scientific principles within mechanical services engineering Glossary of terms Term Explanation Alloy A metal made up of a combination of two or more materials. Atmospheric pressure The weight of air creates a pressure on the Earth’s surface and the pressure exerted by the weight of air pressing down on the ground below will vary depending on the ground’s height above sea level. Boiling When a liquid vaporises. Capillary action When water is drawn
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change in the system. The temperature of boiling water is 212 degrees‚ as is the temperature of steam. boiling water and steam cannot get any hotter than that unless you increase the pressure. So the temperature of each is the same at the same atmospheric pressure. The key difference is this: to get water at 212 degrees to turn to steam at 212 degrees you must add a lot more energy. Thus steam contains much more energy than water at the same temperature‚ which is why steam burns are so much worse
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11 Using Energy © 2010 Pearson Education‚ Inc. Slide 1 © 2010 Pearson Education‚ Inc. Slide 2 © 2010 Pearson Education‚ Inc. Slide 3 © 2010 Pearson Education‚ Inc. Slide 4 Reading Quiz 1. A machine uses 1000 J of electric energy to raise a heavy mass‚ increasing its potential energy by 300 J. What is the efficiency of this process? A. B. C. D. E. 100% 85% 70% 35% 30% © 2010 Pearson Education‚ Inc. Slide 5 Reading Quiz 2. When the temperature of an ideal
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Pituitary Anterior – Located in the base of the brain attached to the hypothalamus. Growth Hormone(GH) – Stimulates an increase in size and rate of division of body cells; enhances movement of amino acids through membranes; promotes growth of long bones. Prolactin (PRL) – Sustains milk production after birth; amplifies effect of LH in males. Thyroid-stimulating Hormone (TSH) – Controls secretion of hormones from the thyroid gland. Adrenocorticotropic Hormone (ACTH) – Controls secretion of certain
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