I was sitting during a lecture last week in one of my classes, and we were talking about chemical warfare and the history behind it. My teacher had brought up the use of Napalm during Vietnam. After a few minutes of talking about how it was used, she mentioned it burned at around 4 million degrees Fahrenheit. This seemed to be inaccurate to me, and all I've been able to find online is that it burns between 1,200 to 5,000 degrees Fahrenheit. Which of the two is accurate? Or is neither?
Your online research is correct. Napalm relies on oxygen in the atmosphere in order to burn, so it produces just an ordinary flame.
Ordinary flames reach equilibrium at less than few thousand degrees as radiation and convection carry away the limited energy output available from oxygen travelling towards the fuel.
A traditional flame is an "oxidation" process which releases energy by replacing oxygen double bonds with lower energy bonds. When the fuel is a hydrocarbon, as it is with napalm, oxygen is available only from the atmosphere. While the fuel is concentrated in a solid/liquid state, the gaseous oxygen in the atmosphere takes it time to get to the napalm. This is a major factor limiting the temperature of flames.