Chemical Reactions Unit Test Part 4 31-40

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What is a physical change?

Back

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include changes in state (like melting or freezing) or changes in appearance (like cutting or crushing).

Front

What is a chemical change?

Back

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 rusting of iron, burning wood, or baking a cake.

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What is the difference between a physical change and a chemical change?

Back

A physical change only changes the appearance or state of a substance without changing its chemical identity, while a chemical change results in the formation of new substances.

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What is an endothermic reaction?

Back

An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in a decrease in temperature. An example is the reaction of baking soda with vinegar.

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What is an exothermic reaction?

Back

An exothermic reaction is a chemical reaction that releases heat to its surroundings, resulting in an increase in temperature. An example is the combustion of fuels.

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What happens to temperature in an endothermic reaction?

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In an endothermic reaction, the temperature of the surroundings decreases because the reaction absorbs heat.

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What happens to temperature in an exothermic reaction?

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In an exothermic reaction, the temperature of the surroundings increases because the reaction releases heat.

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What is a reactant in a chemical reaction?

Back

A reactant is a substance that undergoes a chemical change in a reaction. It is present at the start of the reaction.

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What is a product in a chemical reaction?

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A product is a substance that is formed as a result of a chemical reaction. It is present at the end of the reaction.

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What is the law of conservation of mass?

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The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.