Thermal

What is internal energy?

The internal energy of a body is the sum of the kinetic and potential energies of all its particles. These energies are randomly distributed.

What are the two ways to increase the internal energy of a system?

Do work on the system, for example, by moving its particles or changing its shape and increase the temperature of the system.

How does the internal energy of a substance change when its state changes?

The internal energy changes because the potential energy of the system changes, while the kinetic energy remains constant. For example, when water boils, the energy gained through heating is used to break the bonds between water molecules.

What formula can you use to calculate the amount of energy required to change the temperature of a substance?

Q = mcΔθ where Q = energy required, m = mass, c = specific heat capacity, and Δθ = change in temperature.

What is specific heat capacity?

The specific heat capacity of a substance is the amount of energy required to increase the temperature of 1 kg of the substance by 1 °C or 1 K without changing its state.

What formula can you use to calculate the amount of energy required to change the state of a substance?

Q = m*l where Q = energy required, m = mass, and l = specific latent heat.

What is specific latent heat? What are the two types of specific latent heat?

Specific latent heat is the amount of energy required to change the state of 1 kg of a material, without changing its temperature. The two types are specific latent heat of fusion and specific latent heat of vaporisation.

How do you calculate the energy required to increase the temperature of water in a kettle?

Calculate Q using Q = mcΔθ and then calculate time using t = Q/P, where P is the power of the kettle.

How to find the final temperature when mixing ice and water?

Calculate the energy required to change the state of the ice and set up simultaneous equations for energy transfer in both water and ice.

What are the gas laws?

The gas laws describe the experimental relationship between pressure, volume, and temperature for a fixed mass of gas. The three key laws are Boyle's Law, Charles' Law, and the Pressure Law.

What is the absolute scale of temperature?

The absolute scale of temperature is the Kelvin scale, where all equations in thermal physics use temperatures measured in Kelvin.

How do you convert between Celsius and Kelvin?

K = C + 273, where K is the temperature in Kelvin and C is the temperature in Celsius.

What is absolute zero?

Absolute zero (-273°C) is the lowest possible temperature where particles have no kinetic energy.

What are the combined and ideal gas equations?

The gas laws can be combined into pV = kT, rewritten as pV = nRT, where n = number of moles and R = the molar gas constant.

What is a mole? How can you convert between number of moles and number of molecules?

1 mole of a substance is equal to 6.02 × 10²³ atoms/molecules. To convert, multiply the number of moles by Avogadro's constant.

What is the formula for the ideal gas equation in terms of the number of molecules?

Substituting n = N/NA into pV = nRT gives pV = (NRT)/NA, simplified to pV = NkT.

What is molar mass?

Molar mass is the mass of one mole of a substance, found by determining the relative molecular mass.

How do you calculate the work done on a gas to change its volume at constant pressure?

Work done is calculated using W = p*ΔV, where p = pressure and ΔV = change in volume.

What is Brownian motion?

Brownian motion is the random motion of larger particles in a fluid caused by collisions with surrounding particles.

How does the simple molecular model explain the gas laws?

Boyle's Law: Increased volume decreases pressure due to fewer collisions. Charles's Law: Increased temperature increases volume. Pressure Law: Increased temperature leads to increased pressure at constant volume.

What is the kinetic theory model?

The kinetic theory model arose from theory unlike empirical gas laws, relating pressure, volume, and mean kinetic energy.

What are the assumptions of the kinetic theory model?

1. No intermolecular forces. 2. Negligible collision duration. 3. Random motion and elastic collisions. 4. Follows Newton's laws. 5. Straight line motion between collisions.

What is the derivation of the kinetic theory model equation?

Derives from considering gas molecules colliding with walls, analyzing momentum, impulse, and using volume relationships.

What is an ideal gas? What is the internal energy of an ideal gas equal to?

An ideal gas follows gas laws perfectly, having no intermolecular forces and thus its internal energy is solely kinetic.

What are the formulas for the kinetic energy of a single gas molecule?

1/2 m(c²), 1/2 m(crms²) = 3/2 kT, 3/2 NA kT = 3/2 RT.

How does the kinetic energy of a gas molecule relate to temperature?

The kinetic energy of a gas molecule is directly proportional to temperature in Kelvin.

How to calculate the sum of kinetic energies of oxygen molecules?

Use the number of moles to find molecules and apply the formula 3/2 kT to find kinetic energy.

How has scientific knowledge and understanding of gases changed over time?

Gas laws discovered by various scientists later explained by kinetic theory, adapting over time with experimental evidence.