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Published byEthan Casey Modified over 8 years ago
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Temperature, Heat, and Expansion When matter gets warmer you are giving it energy. This makes the atoms or molecules in the matter move faster -If you get the atoms to move fast enough you can change from solid to liquid to gas. http://www.youtube.com/watch?v=s-KvoVzukHo
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Temperature Temperature is a number that tells you how hot or cold something is compared to a standard. The three major temperature scales; - Fahrenheit - Celsius - Kelvin
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Fahrenheit Temperature Scale Used only in America. 32˚ is the temperature that water freezes 212˚ is the temperature that water boils
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Celsius Temperature Scale Most widely used temperature scale 0˚ is the temperature that water freezes 100˚ is the temperature that water boils This is not an accident. This scale was designed around the freezing and boiling temperatures of water.
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Kelvin Scale The temperature scale used in scientific research. Kelvin temperature measures the amount of energy in an object. Absolute Zero: zero degrees on the Kelvin scale. This is the coldest temperature possible. At this temperature (-273˚ C)the object has no energy.
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Temperature and Kinetic Energy All temperature measurements tell the reader how much energy is in a sample. -If an object has a high temperature, the atoms in the object are moving quickly or have a lot of kinetic energy -If an object has a low temperature, the atoms in the object are moving slowly or have little kinetic energy http://www.youtube.com/watch?v=EH5v54dmb5U
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Heat Heat: the energy that transfers from one object to another because of a temperature difference Thermal Contact: When heat flows from one substance to another one it is in contact with -Heat always flows from the higher temperature substance to the lower temperature substance -This will continue to happen until the two objects are the same temperature
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Thermal Equilibrium When objects that are in thermal contact with each other reach the same temperature. http://www.youtube.com/watch?v=vcgYQ-u7qfc Internal Energy: the grand total of all energies inside a substance - When a substance takes in or gives off heat its internal energy changes.
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Thermal Equilibrium If you pour two liquids that have different temperatures together what temperature will the mixture be? -It depends on the temperatures and amounts of each original liquid T f = M a T a + M b T b + … M a + M b + … T f means final temperature M means mass T means temperature a and b are the different original liquids
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Measurement of Heat The amount of heat transferred can be determined by measuring the temperature change of a known mass of a substance that absorbs the heat. Calorie: the amount of heat required to raise the temperature of one gram of water 1˚ C - a kilocalorie is 1000 calories
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Calculating Calories Q = mC∆T -Q means heat in calories, -m means mass, and -C means the specific heat capacity of a certain material, -∆T means change in temperature
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Specific Heat Capacity The ability of a substance to store heat. -How much heat an object can hold depends on what it is made of Specific Heat: The amount of heat required to raise the temperature of 1 gram of a substance by 1˚ C
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Calculating Specific Heat Capacity C = Q/m∆T - C means the specific heat capacity of a certain material, - Q means heat gained in calories, - m means mass, and - ∆T means change in temperature
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Water’s Specific Heat Capacity Water has a very high specific heat = 4.18 J/g ˚C - This means that it takes a lot of energy to heat water up but when it get warm it takes a long time to cool down - Fall and early winter temperatures along the great lake shores
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Thermal Expansion When the temperature of an object is increased, its molecules jiggle faster and normally that makes the atoms move farther apart. -This makes objects expand when they get warmer http://www.youtube.com/watch?v=eWaCANk0tWo http://www.youtube.com/watch?v=hX2Y2IDjuGI&feature=related H:\Chemistry\Gas Laws\Copy of Can Crush Demo - Tank Car Crush Demo.htm
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Bimetallic Strip Bimetallic Strip: two strips of different metals that are welded or riveted together. -The two different metals will expand at Different rates when expose to heat -This will make the strip bend when it is heated http://www.youtube.com/watch?v=WzX5tpC8Bs8 http://www.youtube.com/watch?v=O6sD6b_3GLg&feature=related
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Thermostat Thermostat: is used to measure the heat in a house and shut off a furnace when the house has reached a certain temperature. -A bimetallic strip in the thermostat will bend as The temperature in the house changes -When it expands to a certain point it will shut off a switch to the furnace http://www.youtube.com/watch?v=-9cUXFMi6e8
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Expansion of Water Most liquids expand when they are heated. Water does not! -Water reduces its volume when it thaws from ice to liquid water -This happens because water will expand as it freezes
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Ice is Less Dense than Liquid Water -Because water gets larger when it freezes it is less dense when solid than when it is a liquid. -This is why ice floats.
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Can an entire freeze over from top to bottom? - Usually not. This is good for fish so that they can survive the winter. -For a body of water to freeze the entire body of water must be 4˚ C then ice can start forming on top. After that the ice forms from the top down.
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