Final answer:
R134a, or Freon-12, is not mildly flammable and is classified as nonflammable. At room temperature, it exists as a gas. The storage warnings are present to prevent the canister from rupturing due to increased pressure when heated.
Step-by-step explanation:
No, R134a, also known as Freon-12, is not mildly flammable; it is classified as a Class 1 substance in the ASHRAE scale meaning it shows no flame propagation when tested in air at 21°C and 101 kPa. As for its state at room temperature, Freon-12 has a boiling point of -29.8°C, which means that at room temperature (25°C), it would be a gas. Regarding storage warnings, pressurized cans of Freon-12 should be kept at temperatures below 120°F (48.8°C) to avoid the risk of the canister rupturing due to increased pressure from the heated gas; if incinerated, the increased pressure may lead to an explosion.
When considering the scenario of a can at 24°C and 360 kPa in a car reaching 50°C, we can refer to the ideal gas law to understand how the pressure inside the can would increase with temperature. Assuming the volume of the gas and the number of moles of the gas remain constant, the pressure would increase in proportion to the absolute temperature. This is a practical illustration of how gas laws can predict the behavior of materials responding to temperature changes in a closed system.