Semester 1 Review

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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 changes in state (like melting or freezing) and changes in appearance (like cutting or dissolving).

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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. This process often involves the breaking and forming of chemical bonds. Examples include rusting iron and burning wood.

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

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A physical change does not create a new substance, while a chemical change results in the formation of one or more new substances.

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What happens to the properties of a substance during a chemical change?

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The properties of a substance change during a chemical change because the original substance is transformed into a new substance with different properties.

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What is an example of a physical change that results in a color change?

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An example is when a red candy dissolves in water, turning the water pink.

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What is the definition of an element in chemistry?

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An element is a pure substance that cannot be broken down into simpler substances by chemical means. Each element is made up of atoms of the same type.

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How many elements are in the chemical formula NaHCO₃?

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There are 4 elements in the chemical formula NaHCO₃: Sodium (Na), Hydrogen (H), Carbon (C), and Oxygen (O).

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What is an endothermic reaction?

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

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What is an exothermic reaction?

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An exothermic reaction is a chemical reaction that releases heat to its surroundings, resulting in an increase in temperature.

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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.