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Absolute Zero -273.15 0 C, 0 Kelvin Charless Law

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Absolute Zero Theoretically, absolute zero is the lowest temperature that can be reached. Absolute zero has never been reached. Temperatures within a millionth of a degree above -273.15 0 C have been achieved!

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Lord Kelvin The Kelvin scale is named after Lord Kelvin and his scale starts at 0 degrees Kelvin, which is called absolute zero. The Kelvin Scale measures the coldest temperature there can be.

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Lord Kelvin 1824 - 1907 Lord Kelvin said there was no upper limit of how hot things can get, but there was a limit as to how cold things can get. Kelvin developed the idea of Absolute Zero: - 273.15 degrees Celsius! At this temperature, no heat energy remains in a substance, the average kinetic energy is zero and all molecular motion ceases.

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Kelvin Scale - 273.15 0 C is usually rounded to - 273.15 0 C The zero point on the Kelvin Scale is absolute zero K = 273 + 0 C Kelvin is the SI unit of temperature

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Charless Law V 1 /T 1 = V 2 /T 2 By measuring and graphing the volume and temperature of a gas and extrapolating to 0 volume, absolute zero can be determined.

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Straight Line Equation y = mx + b y and x are variables y = temperature x = volume m and b are constants m = slope of the line b = y intercept

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Straight Line Equation y = mx + b When b = 0, the line equation is: y = mx + b This is a direct proportion -- the special case of a straight line having a y-intercept = to zero.

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Straight Line Equation y = mx + b When b = 0, the line equation is: y = mx + b In Charles Law: y = Volume x = Kelvin Temperature m = k 2 proportionality constant for a particular pressure

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Charless Law Charless Law states: At constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature. K 2 = V/T V 1 /T 1 = K 2 = V 2 /T 2 V 1 /T 1 = V 2 /T 2

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Linear Regression Linear regression analyzes the relationship between two variables, X and Y. For each subject (or experimental unit), you know both X and Y and you want to find the best straight line through the data. In some situations (like finding absolute zero), the slope and/or intercept have a scientific meaning.

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Linear Regression The goal of linear regression is to adjust the values of slope and intercept to find the line that best predicts Y from X. The slope quantifies the steepness of the line. It equals the change in Y for each unit change in X. It is expressed in the units of the Y-axis divided by the units of the X-axis. The Y intercept is the Y value of the line when X equals zero. It defines the elevation of the line.

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TI-83 Linear Regression Clear Previous Data: Stat Up arrow to L 1 Clear Enter Move cursor arrow to L 2 Clear Enter

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TI-83 Linear Regression Enter x values: < Enter all x values in L 1 Enter after each value

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TI-83 Linear Regression Enter y values: > Enter all y values in L 2 Enter after each value

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TI-83 Linear Regression Find slope (b), Intercept (a), and correlation coefficient (r): Stat Move cursor to calc 8 2nd 1, 2nd 2

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Linear Regression If the slope is positive, Y increases as X increases. If the slope is negative, Y decreases as X increases. The Y intercept is the Y value of the line when X equals zero. It defines the elevation of the line.

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Linear Regression Is the slope positive or negative for determining absolute zero?

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Volume-Temperature Graph 5 10 15 20 25 30 Volume (mL) Temperature ( C) 0 100 – 273

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