Is burning a chemical or physical change? Explain your answer.

Burning is a chemical change because it has a chemical reaction and results in a new substance. A physical change does not cause the substance to change. For example, melting ice is a physical change because in the liquid state, water is made up of 2 parts hydrogen and one part oxygenm just as it is in the solid state. The only change is the state of matter from a solid to a liquid.
Baking a cake, represents a chemical change however, because we have taken the sugar, flour, eggs, etc. and chemically altered them. They are no longer separate substances, but have now merged and formed a new substance.
Other sources: chem4kids.com

Burning is a chemical change since it is a reaction between substances, usually including oxygen and usually accompanied by the generation of heat and light in the form of flame. The rate or at which the reactants combine is high, in part because of the nature of the chemical reaction itself and in part because more energy is generated than can escape into the surrounding medium, with the result that the temperature of the reactants is raised to accelerate the reaction even more. A familiar example is a lighted match.Properly ignited, the heat from the flame raises the temperature of a nearby layer of the matchstick and of oxygen in the air, and the wood and oxygen react in.When equilibrium between the total heat energies of the reactants and the total heat energies of the products is reached, combustion stops.The emission of light in the flame results from the presence of excited particles'usually charged atoms,molecules and electrons.

Burning, or combustion, is a chemical change, and one of the most dramatic to observe. A chemical change happens when the molecular structure of a substance changes in a way that cannot be reversed. When a substance burns, its molecular bonds are broken down, and it becomes a different substance. When one burns carbon compounds, for example, new chemicals are produced—including (depending on the amount of oxygen present) carbon dioxide and carbon monoxide. When wood is burned, it is reduced to ash, and gases escape. The fact that combustion gives off heat and light in addition to changing the chemical composition of the fuel is another indicator that it is a chemical change. Also, (as mentioned above) unlike a physical change, a chemical change cannot be undone. If water freezes, it can be thawed, and, conversely, running water can be frozen. If a piece of firewood burns into ashes, these ashes cannot be reformed into wood.
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