Physics Chapter: Thermometers and Gas Laws
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Questions and Answers

What property allows a bimetallic strip to function in a thermometer?

  • The strip can conduct electricity.
  • The metals change color with temperature.
  • Different coefficients of linear expansion in metal. (correct)
  • The strip reacts chemically with temperature changes.

    • According to Boyle's Law, what happens to the product of pressure and volume if the temperature remains constant?

  • It increases as volume increases.
  • It varies directly with the temperature.
  • It remains constant regardless of changes. (correct)
  • It decreases as pressure increases.

    • What is the significance of the temperature −273°C in relation to Charles's Law?

  • It represents the point where volume becomes zero. (correct)
  • It indicates the temperature beyond which volume cannot increase.
  • It marks the temperature at which gases turn into liquids.
  • It is the temperature at which gas has maximum pressure.

    • Which variable is NOT one of the four main variables associated with gases?

    <p>Density</p> Signup and view all the answers

    What will happen to the volume of a gas if the temperature is increased while keeping pressure constant, according to Charles's Law?

    <p>The volume will increase.</p> Signup and view all the answers

    What does Boyle's Law state about the relationship between pressure and volume for a fixed mass of gas at constant temperature?

    <p>The product of pressure and volume is constant.</p> Signup and view all the answers

    What happens to the volume of a gas when it is heated at constant pressure according to Charles's Law?

    <p>The volume is directly proportional to the absolute temperature.</p> Signup and view all the answers

    At what temperature does Charles's Law suggest that a gas would have zero volume?

    <p>-273°C</p> Signup and view all the answers

    What characteristic of the graph of volume versus temperature in Charles's Law indicates the relationship between the two variables?

    <p>The graph is a straight line.</p> Signup and view all the answers

    In the context of gas laws, what remains constant according to Boyle's Law?

    <p>The product of pressure and volume.</p> Signup and view all the answers

    What is the relationship between the number of moles, mass, and molecular weight of a substance?

    <p>n = rac{m}{M}</p> Signup and view all the answers

    In the equation PV = nRT, what do the variables R, P, and T represent?

    <p>Universal gas constant, pressure, temperature in Kelvin</p> Signup and view all the answers

    Given an air storage tank with an initial pressure of 18 atm and 3 kg of air at 112 liters, how much air is required to increase the pressure to 21 atm?

    <p>3.5 kg</p> Signup and view all the answers

    What is the approximate value of Avogadro's number?

    <p>6.022 x 10^23</p> Signup and view all the answers

    What would be the mass of air in kg when the pressure is increased from 18 atm to 21 atm under the same volume?

    <p>3.5 kg</p> Signup and view all the answers

    What does Boyle's Law state about pressure and volume?

    <p>The product of pressure and volume is constant at a fixed temperature.</p> Signup and view all the answers

    Which equation represents Charles's Law?

    <p>V₁/T₁ = V₂/T₂</p> Signup and view all the answers

    What does the constant PV/T represent in the general gas law?

    <p>The constant of proportionality for any mass of gas.</p> Signup and view all the answers

    How is the number of moles defined in relation to a substance?

    <p>It's the number of molecules in 12 grams of carbon-12.</p> Signup and view all the answers

    What does the kinetic theory of gases primarily assume about the composition of gas particles?

    <p>A gas consists of identical particles called molecules.</p> Signup and view all the answers

    What happens to the volume of a gas when the temperature increases, according to Charles's Law?

    <p>The volume increases if pressure remains constant.</p> Signup and view all the answers

    How many liters does one mole of gas occupy at standard temperature and pressure according to the ideal gas law?

    <p>22.4 liters</p> Signup and view all the answers

    What is the purpose of the ideal gas law in the context provided?

    <p>To calculate the volume occupied by a mole of gas.</p> Signup and view all the answers

    Which factor does not affect the value of the constant in PV/T = constant?

    <p>Type of gas being measured.</p> Signup and view all the answers

    What is the significance of the large number of molecules in a finite volume of gas?

    <p>It ensures that the gas behaves according to ideal gas laws.</p> Signup and view all the answers

    Which of the following correctly identifies the universal gas constant (R)?

    <p>R has a fixed value, commonly used in gas law calculations.</p> Signup and view all the answers

    What does the term 'Avogadro's number' relate to?

    <p>The mass of a substance and its molecular number.</p> Signup and view all the answers

    Given a temperature of 0°C, what is the equivalent temperature in Kelvin used in gas calculations?

    <p>273 K</p> Signup and view all the answers

    What is the approximate diameter of a molecule in cubic metres?

    <p>3 x 10^-10 m</p> Signup and view all the answers

    What happens to molecules in a gas under standard conditions concerning their distances from each other?

    <p>They are separated by vast distances compared to their dimensions.</p> Signup and view all the answers

    In the context of gas behavior, what does the term 'perfectly elastic' refer to?

    <p>Molecules bounce off container walls without losing energy.</p> Signup and view all the answers

    According to kinetic theory, how do molecules behave in the absence of external forces?

    <p>They move freely in straight lines.</p> Signup and view all the answers

    When calculating pressure in an ideal gas, which element is important regarding the dimensions of the vessel?

    <p>The edge length of the cubical vessel.</p> Signup and view all the answers

    What does specific heat capacity measure?

    <p>The heat required to raise the temperature of a substance's unit mass by unit degree</p> Signup and view all the answers

    Which equation represents the relationship between average translational kinetic energy and absolute temperature?

    <p>$ rac{1}{2} m ar{v^{2}} = rac{3}{2} kT$</p> Signup and view all the answers

    What does Charles's Law indicate about the relationship between volume and temperature when pressure is constant?

    <p>Volume is proportional to temperature</p> Signup and view all the answers

    Which of the following would you expect to have the highest specific heat capacity?

    <p>Water</p> Signup and view all the answers

    In which scenario does Boyle's Law apply?

    <p>When pressure increases at constant temperature, causing volume to decrease</p> Signup and view all the answers

    What describes the work done by the gas during expansion in a thermodynamic system?

    <p>The product of pressure and the change in volume.</p> Signup and view all the answers

    In a gas expansion scenario, if the pressure is constant and the volume increases, what happens to the work done by the gas?

    <p>The work done increases.</p> Signup and view all the answers

    In the given thermodynamic system, what is the significance of the movable piston?

    <p>It enables the gas to perform work through expansion.</p> Signup and view all the answers

    What parameters define the work done by a gas in a cylinder during expansion?

    <p>Pressure and the change in volume.</p> Signup and view all the answers

    If the volume of gas in the cylinder is represented as $V$ and it expands to $V + \Delta V$, which formula would represent the change in work done?

    <p>$W = P \times \Delta V$</p> Signup and view all the answers

    What does the equation ΔQ − ΔW = ΔU represent in thermodynamics?

    <p>The change in internal energy of the system</p> Signup and view all the answers

    In an isolated system, what happens to the internal energy when no external work is done and no heat is exchanged?

    <p>It remains constant</p> Signup and view all the answers

    Which of the following statements about ΔQ and ΔW is true?

    <p>They depend on the changes in the system's state</p> Signup and view all the answers

    What happens to the relationship ΔQ − ΔW for a system if the process is repeated along different paths?

    <p>It remains constant regardless of the paths</p> Signup and view all the answers

    In the context of the First Law of Thermodynamics, what does an increase in the internal energy of a system imply?

    <p>More heat is absorbed than work is done by the system</p> Signup and view all the answers

    What characterizes an isobaric process?

    <p>It occurs at constant pressure.</p> Signup and view all the answers

    In an isobaric process where 1000 Joules of heat is absorbed and 600 Joules of work is delivered, how much heat is lost due to conduction?

    <p>100 Joules</p> Signup and view all the answers

    What is the correct expression used to calculate the heat transfer in a thermodynamic system when internal energy decreases by 300 J and 120 J of work is done on the system?

    <p>ΔQ = ΔU + ΔW</p> Signup and view all the answers

    If the internal energy change (ΔU) of a system is zero during an isobaric process, which of the following statements is true?

    <p>Heat added equals work done on the system.</p> Signup and view all the answers

    In the context of the isobaric process, how is work (ΔW) defined mathematically?

    <p>ΔW = P( ext{ΔV})</p> Signup and view all the answers

    Study Notes

    Bimetallic Thermometers

    • Bimetallic strips consist of two metals with different coefficients of linear expansion.
    • When heated, the strip bends due to the different expansion rates of the two metals.
    • Thermometers utilize this bending property by forming a coil with a fixed end and a pointer attached to the other end.
    • The pointer's movement directly correlates with the temperature changes.

    Gas Laws

    • Gases lack fixed volume or shape.
    • Their volume changes with pressure and temperature.
    • The variables describing gases are pressure, volume, mass, and temperature.
    • Boyle's Law states that the product of pressure and volume is constant at constant mass and temperature.
    • Charles's Law states that volume is directly proportional to absolute temperature at constant pressure.
    • Extrapolating the volume-temperature graph at constant pressure intersects the temperature axis at -273°C, representing absolute zero.

    Boyle's Law

    • For a fixed mass of gas at constant temperature, the product of pressure and volume is constant: PV = constant.

    Charles's Law

    • When a given mass of gas is heated at constant pressure, the volume is directly proportional to absolute temperature: V/T = constant.
    • A graph of volume against temperature yields a straight line.
    • The line extrapolates to -273°C, indicating a hypothetical zero volume at absolute zero.

    General Gas Law

    • Combining Boyle's Law and Charles's Law: PV/T = constant.
    • The proportionality constant (PV/T) is determined for a specific mass of gas given pressure, volume, and absolute temperature.
    • It is not consistent for different samples of the same gas due to differing mass and molecular number.
    • Moles (n) represent the amount of gas in a given volume.
    • A mole of a substance contains the same number of atoms or molecules as there are atoms in 12 grams of carbon-12.

    Gas Laws and Molecular Weight

    • The mass of a substance containing a specific number of molecules is defined by Avogadro's number (N).
    • N = 6.022 x 10^23 molecules/mole, representing the number of atoms in 12 grams of carbon-12.
    • The number of moles (n) is related to mass (m) and molecular weight (M) by: n = m/M.
    • The ideal gas law combines pressure, volume, number of moles, and temperature: PV = nRT.
    • R represents the universal gas constant.

    Properties of Gases: Kinetic Interpretation

    • Kinetic theory predicts the properties of matter.
    • Key assumptions:
      • Gases consist of molecules with one or more atoms.
      • A finite volume contains a large number of molecules.
    • Example calculation:
      • V = (nRT)/P demonstrates the volume occupied by one mole of gas at a given temperature and pressure.

    Kinetic Interpretation of Gases

    • At standard conditions, 3 x 10^25 molecules exist in a cubic meter.
    • Molecules are vastly separated compared to their dimensions.

    Properties of Molecules

    • Molecules move randomly with various speeds.
    • Collisions with container walls are perfectly elastic.
    • Molecules exert negligible forces on each other except during collisions.
    • Without external forces, molecules move in straight lines.

    Kinetic Theory of Gases

    • The average translational kinetic energy per molecule is directly proportional to the absolute temperature: 1/2 m(v^2) = 3/2 kT.

    Gas Laws and Temperature

    • Boyle's Law: PV = constant at constant temperature.
    • Charles's Law: V/T = constant at constant pressure.
    • Combining these laws: V = NkT/P.

    Specific Heat Capacity

    • Different substances require varying amounts of heat to raise their temperature by the same amount.
    • Specific heat (C) is the heat needed to raise unit mass by one degree: C = ΔQ/ΔT.
    • Examples highlight the varying heat requirements for materials like copper, water, and paraffin.

    Heat and Work in Thermodynamics

    • Thermodynamics deals with energy conversion to and from heat.
    • Figure 11.6 illustrates a gas in a cylinder with a movable piston.
    • Work done by the gas during expansion: w = PΔV.

    The First Law of Thermodynamics

    • ΔQ - ΔW represents the change in the system's energy.
    • ΔQ is energy added, and ΔW is energy extracted through work.
    • The difference remains constant regardless of the path taken, demonstrating energy conservation.

    Special Cases

    • An isolated system does no work and exchanges no heat with its surroundings.
    • ΔW = 0 and ΔQ = 0.
    • The internal energy of an isolated system remains constant: ΔU = 0, maintaining the conservation of energy principle.

    Applications of Energy - Isobaric Process

    • Occurs at constant pressure.
    • Examples include boiler, vaporization, or heating processes.
    • Internal energy change (ΔU) is zero.
    • Equations used include:
      • ΔU = ΔQ - ΔW
      • ΔW = P(ΔV)
    • Examples 11.6 and 11.7 demonstrate calculations involving heat, work, and internal energy changes in isobaric processes.

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    Description

    This quiz covers key concepts related to bimetallic thermometers and the fundamental gas laws. Explore how the properties of gases change with pressure and temperature, including Boyle's and Charles's laws. Test your understanding of these essential physics topics.

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