Technical Standards and Safety Authority (TSSA) G3 Practice Exam

A Bunsen flame is caused by:

1. premixing air and fuel prior to combustion

2. not premixing air and fuel prior to combustion

3. a low ignition temperature

4. the presence of carbon monoxide

The correct answer is: premixing air and fuel prior to combustion

A Bunsen flame is indeed caused by premixing air and fuel prior to combustion. In a Bunsen burner, the design allows for a controlled mixing of air with the gas, which provides an adequate supply of oxygen to support combustion. This mixing creates an adjustable flame—typically a blue, hotter flame when the correct ratio of air to gas is achieved. This is important because the efficiency and characteristics of the flame, such as temperature and color, are significantly influenced by the way air and gas are mixed. When the air-fuel mixture is optimal, it leads to complete combustion, minimizing soot production and creating a clean flame, which is essential in laboratory settings for various applications, such as heating and sterilization. The other potential causes, such as not premixing air and fuel, a low ignition temperature, or the presence of carbon monoxide, do not explain the phenomenon of the Bunsen flame adequately and can lead to either incomplete combustion or dangerous conditions.