Final answer:
When ethylene is heated at constant pressure, it can undergo reactions such as polymerization to form polyethylene, combustion to produce carbon dioxide and water with the release of heat (∆H), or cracking to produce smaller hydrocarbons.
Step-by-step explanation:
When ethylene is heated at constant pressure, it can undergo a variety of chemical reactions depending on the presence of catalysts and conditions. One common reaction is polymerization, where ethylene molecules react to form long chains of polyethylene, a type of plastic. Another possibility is combustion if the ethylene mixture has enough oxygen; ethylene reacts with oxygen to form carbon dioxide and water, releasing heat (∆H).
During the combustion reaction, the amount of heat released can be measured as the change in enthalpy (∆H) at constant pressure. Furthermore, in a process known as 'cracking', high temperatures can cause the decomposition of larger hydrocarbons into smaller ones, including ethylene.
It's important to note that without proper conditions or catalysts, ethylene might not react significantly even when heated. Various industrial processes utilize the heat-induced reactions of ethylene for producing valuable chemicals and polymers.