IB Physics SL B.1.9 Specific heat & latent heat

Apply Q = mcΔT and Q = mL in single- and multi-step heating problems, checking units, power-time data and energy balance.

Exam points

use Q = mcΔT with P = E/t when needed to calculate c, ΔT or energy, checking kg and K units
use Q = mL at the phase point to find energy transferred or mass melted or vaporized
set up an energy-balance equation from a data table to compare specific heat capacities at equilibrium

[Maximum number: 3]

This question is in two parts. Part 1 is about ideal gases and specific heat capacity. Part 2 is about simple harmonic motion and waves.
Part 1 Ideal gases and specific heat capacity

Argon behaves as an ideal gas for a large range of temperatures and pressures. One mole of argon is confined in a cylinder by a freely moving piston.

The temperature of the argon is 300 K . The piston is fixed and the argon is heated at constant volume such that its internal energy increases by 620 J . The temperature of the argon is now 350 K .

Determine the specific heat capacity of argon in $\mathrm{Jkg}^{-1} \mathrm{~K}^{-1}$ under the condition of constant volume. (The molecular weight of argon is 40 )

Mass of gas $=0.040\ \mathrm{kg}$ .
$c=Q/(m\Delta T)$ , or $620=0.040\times c\times50$ .
$c=310\ \mathrm{J\ kg^{-1}\ K^{-1}}$ .

c=\frac{620}{0.040\times50}=310\ \mathrm{J\ kg^{-1}\ K^{-1}}

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B.1.9—Specific heat and latent heat question 1