Thermodynamics Flashcards
What is specific heat capacity?
Energy required per unit mass to raise temperature by 1 K or 1 °C.
What is the formula for specific heat capacity?
c = E / (m × Δθ)
What is specific latent heat?
Energy required per unit mass to change the state of a substance.
What is specific latent heat of fusion?
Energy per unit mass to change from solid to liquid with no temperature change.
What is specific latent heat of vaporization?
Energy per unit mass to change from liquid to gas with no temperature change.
What is the formula for specific latent heat?
L = E / m
Why is latent heat of vaporization greater than fusion?
More volume increase during vaporization, more work against atmosphere, and particles are separated further.
What is internal energy?
Sum of random kinetic and potential energies of molecules in a system.
What happens to internal energy when temperature increases?
It increases due to rise in kinetic energy.
What is the first law of thermodynamics?
ΔU = q + w (internal energy change = heat supplied + work done on system)
What does positive work mean in thermodynamics?
Work is done on the system (e.g. compressing a gas).
What does negative work mean in thermodynamics?
Work is done by the system (e.g. gas expansion).
What is the formula for work done on a system?
w = P × ΔV
When is work done zero in thermodynamics?
When volume of the system doesn’t change.
How do you determine latent heat of vaporization experimentally?
Measure temperature vs time, calculate power as VI, and use graph gradient for Δθ/Δt.
What is the power formula for heating?
P = VI
How do you find specific heat capacity experimentally?
Use: VI = mc × gradient, where gradient is Δθ/Δt from temperature-time graph.
How do you find latent heat using a mass-time graph?
Use: lv = power ÷ gradient, where gradient is Δm/Δt from mass-time graph.
What is the internal energy formula in terms of kinetic and potential energy?
Internal Energy = Total KE + Total PE
What happens to internal energy when gas is compressed with no heat exchange?
No change in internal energy (ΔU = 0)
What happens to internal energy when solid is heated?
Internal energy increases because q = +
What happens to internal energy during melting of ice?
Internal energy increases because q = +
Why does boiling water do external work?
Because volume increases as it turns to gas
Why does internal energy increase when water turns to steam?
Kinetic energy stays constant but potential energy increases as molecules move further apart.
