A fixed mass of oxygen changes phase from liquid to gas at a constant temperature.
Explain the change in the total internal energy of the oxygen.
In a packaging factory, oxygen gas is added to sealed packages to extend the shelf life of food. In 1.0 hour1.0\text{ hour}1.0 hour, the factory uses 12 m312\text{ m}^312 m3 of oxygen gas at a pressure of 110 kPa110\text{ kPa}110 kPa and a temperature of 27∘C27^\circ\text{C}27∘C.
Show that the number of moles nnn of oxygen used per hour is about 530530530.
Calculate the mass of oxygen gas used in one hour.
molar mass of oxygen=0.032 kg mol−1\text{molar mass of oxygen} = 0.032\text{ kg mol}^{-1}molar mass of oxygen=0.032 kg mol−1
The volume of oxygen being used cannot be changed.
State how the rate of mass of oxygen used can be reduced.
The oxygen at the factory is stored as a liquid. The liquid expands at constant temperature to form gas in a short section of pipe.
When the surrounding air temperature is 0∘C0^\circ\text{C}0∘C, a thick layer of ice forms on the outside of the pipe from water vapour in the air. In 1.0 hour1.0\text{ hour}1.0 hour, the mass of ice formed is 1.1 kg1.1\text{ kg}1.1 kg at a temperature of 0∘C0^\circ\text{C}0∘C.
Use this data and your answer to (b)(ii) to estimate the specific latent heat of vaporisation LLL of oxygen.
56 exam-style questions on OCR A A Level Physics Thermal physics, covering Temperature, Solid, liquid and gas, Thermal properties of materials, and Ideal gases. Each one has a worked solution and a mark scheme showing where the marks go.