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43 Cards in this Set
- Front
- Back
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What is temperature measured with in thermal physics?
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The Kelvin/absolute temperature scale
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What is the unit is temperature measured in in thermal physics?
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Kelvin, K
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What is absolute zero?
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The lowest possible temperature an object can have.
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What is the value of absolute zero?
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-273°C / 0 K
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How much kinetic energy do molecules have at absolute zero?
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No kinetic energy
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What is a molecule's energy proportional to when using the Kelvin scale?
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Its temperature
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How do you convert degrees Celsius into Kelvin?
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Add 273.
K=C+273 Where: • K is temperature in Kelvin • C is temperature in degrees Celsius |
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What does Boyle's Law state?
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At a constant temperature the pressure p and volume V of a gas are inversely proportional.
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What is an ideal gas?
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A gas that obey's: • Boyle's law at all temperatures. • A gas that obeys Charles' law • The pressure law |
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What will the product of p*v always be?
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Constant
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On a pressure-volume graph in what direction will a higher temperature move the curve?
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Further away from the origin
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Following Boyle's law, what happens to the volume of a gas if it's pressure doubles?
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Volume is halved
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What does Charles' law state?
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At constant pressure, the volume V of a gas is directly proportional to its absolute temperature T.
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What is the volume of a gas at absolute zero?
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Zero
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Following Charles' law, what happens if the temperature is doubled?
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The volume doubles.
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If Charles' law is obeyed, what is the volume divided by the temperature?
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Constant
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What does the pressure law state?
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At constant volume, the pressure p of a gas is directly proportional to its absolute temperature T.
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Following the pressure law, what happens if the temperature doubles?
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Pressure doubles
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What is the value for pressure at absolute zero?
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Zero
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If the pressure law is obeyed, what is the pressure divided by the temperature? |
Constant
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What is the Avogadro constant?
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The number of atoms in exactly 12 g of carbon-12.
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What does the Avogadro constant give?
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The number of atoms in any volume of substance whose mass, in grams, is the same as its relative atomic mass.
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What is the value of Avogadro's constant?
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6.02x10^23 mol-¹
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What is the symbol for Avogadro's constant?
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NA
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What is 1 mole of a substance defined as?
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A substance that contains NA atoms or molecules, all of which are identical.
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What is the molar mass of a substance?
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The mass that 1 mole of the substance would have.
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What is molar mass usually measured in? |
grams
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What is molar mass equal to?
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A substances relative atomic or relative molecular mass.
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What is the number of moles in a substance usually given by?
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n
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What is the number of moles in a substance usually measured in?
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mol
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What is the equation for number of molecules in a gas?
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N=n*NA
Where: • N is the number of molecules • n is number of moles • NA is Avogadro's constant |
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What is the molar gas constant, R?
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8.31 Jk-¹
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How do you derive the ideal gas equation?
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• Combine the three laws to get pV/T = constant
• The molar gas constant, R, is used • The value of pV/T depends on how much gas is present so n is used to represent the number of molecules present • Putting all this into one equation gives pV/T=nR • Which can be rearranged to give the ideal gas equation. |
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What is the ideal gas equation?
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pV=nRT
Where: • p is pressure • v is volume • n is number of moles of gas • T is temperature • R is the molar gas constant |
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What is pressure measured in?
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Pa (Pascals)
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What is volume measured in?
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m³ (meters cubed)
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What does the ideal gas law work best for?
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Gases with low pressure and fairly high temperatures
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What is Boltzmann's constant equivalent to?
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R/NA
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What is the symbol for Boltzmann's constant?
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k
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What is the value of Boltzmann's constant?
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1.38x10-23 JK-¹
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What is the equation of state of an ideal gas?
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pV=NkT
Where: • p is pressure • v is volume • N is the number of molecules of gas • T is the temperature • k is the Boltzmann constant |
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How do you derive the pressure of an ideal gas?
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• Imagine a cubic box with sides of length l containing N molecules each of mass m.
• Derive the pressure on one wall of this box in the x direction. • If molecule Q moves directly towards wall A with velocity u it's momentum approaching the wall is mu. • If the collisions are perfectly elastic when the molecule strikes wall A, the molecule will rebound in the opposite direction with momentum -mu. • This makes the change in momentum 2mu. • Assuming there are no collisions with other mokle |
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What is Newton's third law of motion?
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Every action has an equal and opposite reaction |
