Final answer:
A pressure relief valve or a safety valve is designed to open at a specific pressure to prevent container rupture by releasing the contents to lower the pressure.
Step-by-step explanation:
The valve designed to open at a specific pressure to prevent container rupture is called a pressure relief valve or a safety valve. These valves are critical for ensuring the safety of various systems where pressure can build up, such as in gas canisters or steam boilers. When the internal pressure exceeds the predetermined level, the valve opens, releasing some of the contents to bring the pressure back down, thus preventing potential explosions or structural failures. As an example, when air is pumped into a canister, increasing the number of molecules without allowing the canister to expand, the pressure inside the canister increases. If this pressure were to exceed the strength of the canister, it could burst. The pressure relief valve prevents this dangerous scenario by venting gas once the internal pressure reaches a certain threshold. This is analogous to the vapor pressure of water, where pressure is exerted by water vapor in equilibrium with liquid water in a closed container at a specific temperature. However, in the case of gas in a canister, if more air is added and the pressure increases without a way to relieve it, the canister might burst unless a safety mechanism like a pressure relief valve is in place.