Final answer:
A blowtorch or single tank torch commonly used in welding utilizes a mix of acetylene gas and oxygen, known as oxyacetylene, to produce a high-temperature flame for welding metals.
Step-by-step explanation:
A blowtorch or single tank torch used in welding and cutting metals typically utilizes a combination of acetylene gas (C₂H₂) and oxygen (O₂) to create a very hot flame. This is known as an oxyacetylene torch. The process takes advantage of acetylene's high heat of combustion. Acetylene, when burned with oxygen, provides a flame hot enough to melt and join metals. Acetylene is composed of carbon and hydrogen and is a part of the alkyne group of hydrocarbons. It is not only used in welding but also as a precursor to many chemical compounds used in the production of various plastics and resins.
The chemical reaction for the combustion of acetylene using oxygen is: 2 C₂H₂ + 5O₂ → 4 CO₂ + 2H₂O. When calculating the requirements for oxygen to combust acetylene, it's important to use stoichiometry from the balanced chemical equation to determine the correct proportions of each gas needed.