Chemistry - Atomic structure- electrons and stability exercises

This is definitely a chemical reaction. Light energy is emitted from the chemical reaction taking place inside the tube. The reaction is irreversible.

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Remember that collisions are necessary for most reactions to take place. Molecules or atoms in the solid state do not move at all. They simply vibrate in position. Once water is added the molecules are freed and can move about. They now have enough speed to collide with each other and cause a reaction to take place.

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Energy is needed to get the oxygen molecules colliding with enough force to break apart both the molecules in the wood and itself. Once separated the atoms quickly recombine into more stable products, water and carbon dioxide and in the process release more heat to encourage more collisions to take place. This is considered a chemical reaction because new products are formed such as energy, carbon dioxide and water and the process is irreversible.

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Chemical reactions exercises
	Wood does not burn on its own. It needs a little help to get it going. Energy must be supplied in the form of a flame in order for the fire to proceed. Oxygen must be present for the wood to burn. Explain why a flame is needed and the reason why burning of wood is considered a chemical reaction? Solution
The baking of a cake can also be considered a chemical reaction. Now chefs use tartaric acid and baking powder to produce carbon dioxide which expands in the heat of the oven and makes the cake rise. Tartaric acid and baking powder are both solids. Mixing them together in the solid state produces no reaction at all. Only when water is added and the powders dissolve will carbon dioxide be produced. Explain this. Solution
	Glow Sticks, such as the one pictured on the left, are sold in shops as toys. Is there a chemical reaction behind the Glow Stick? Explain. Solution