Final answer:
The DOT requires placards for flammable loads exceeding 1000 lb (454 kg). This requirement ensures safety during transportation. Proper handling and storage of flammable gases and liquids are vital to prevent dangerous increases in pressure and potential explosions.
Step-by-step explanation:
The DOT requires placards for flammable gases and liquids loads that exceed a minimum of 1000 lb (454 kg). This threshold is provided to ensure safe transportation and handling of potentially hazardous materials. Exceeding this weight necessitates clear labeling to warn transporters and emergency responders of the specific risks associated with the material in the event of a spill or accident.
Regarding the given scenarios, the importance of proper storage and handling becomes clear. The warning to store only at temperatures below 120 °F (48.8 °C) and not to incinerate the can is due to the risk of increased pressure leading to explosion or combustion as temperatures rise. Using the gas law principle, if a gas can is left in a car at 50 °C (an increase from the initial 24 °C), pressure in the can will increase due to the temperature rise, posing a danger.
The weight of gasoline exerts pressure at the bottom of a full gas tank, and calculations would reveal the specific pressure based on the weight and the tank's dimensions. In a similar manner, the calculation of the volume of CO₂ and H₂O gas produced by the combustion of liquid propane in a balloon can be performed using the density of the propane and appropriate chemical reaction stoichiometry.