7th Grade Final

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What is a coefficient in a chemical formula?

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A coefficient is a number placed in front of a chemical formula to indicate how many molecules or atoms of that substance are present. For example, in 3H2O, the coefficient 3 indicates there are three molecules of water.

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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. An example is dissolving salt in water.

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What is a chemical change?

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A chemical change occurs when a substance transforms into a different substance with different properties, resulting in the formation of new substances. For example, burning wood.

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What are reactants in a chemical equation?

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Reactants are the starting substances in a chemical reaction, found on the left side of a chemical equation.

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What are products in a chemical equation?

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Products are the substances formed as a result of a chemical reaction, found on the right side of a chemical equation.

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

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In a physical change, no new substances are formed, while in a chemical change, new substances are created.

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What happens to particles in a solid compared to those in a gas?

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Particles in a solid move more slowly than particles in a gas.

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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; it is conserved.

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What is an example of a chemical change?

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An example of a chemical change is rusting iron, where iron reacts with oxygen to form iron oxide.

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What is an example of a physical change?

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An example of a physical change is melting ice into water.