Physical and chemical changes

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What is a physical change?

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A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include melting, freezing, and dissolving.

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What is a chemical change?

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A chemical change is a change that results in the formation of new chemical substances. It involves making or breaking bonds between atoms. Examples include burning, rusting, and digestion.

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What is the law of conservation of mass?

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The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction. The mass of the reactants must equal the mass of the products.

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What is an exothermic reaction?

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An exothermic reaction is a chemical reaction that releases energy in the form of heat. This causes the temperature of the surroundings to increase.

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What is an endothermic reaction?

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An endothermic reaction is a chemical reaction that absorbs energy from its surroundings, resulting in a decrease in temperature.

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What evidence indicates a chemical change has occurred?

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Evidence of a chemical change includes color change, temperature change, gas production, and the formation of a precipitate.

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What happens to the temperature during an exothermic reaction?

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During an exothermic reaction, the temperature of the surroundings increases as heat is released.

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What happens to the temperature during an endothermic reaction?

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During an endothermic reaction, the temperature of the surroundings decreases as heat is absorbed.

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What is the difference between a reactant and a product?

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A reactant is a substance that undergoes a chemical change in a reaction, while a product is a substance that is formed as a result of that reaction.

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What is a balanced chemical equation?

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A balanced chemical equation has the same number of each type of atom on both sides of the equation, indicating that mass is conserved.