Chemical Reactions

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What is a physical change?

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A physical change is a change in the shape or state of a substance without altering its chemical composition.

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What is a chemical change?

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A chemical change is a process where one or more substances are transformed into new substances with different properties.

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What is the difference between reactants and products in a chemical reaction?

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Reactants are the starting substances in a chemical reaction, while products are the substances formed as a result of the reaction.

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What does it mean to balance a chemical equation?

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Balancing a chemical equation means ensuring that the number of atoms for each element is the same on both sides of the equation.

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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.

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How many hydrogen atoms are in the molecule C₃H₈?

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There are 8 hydrogen atoms in the molecule C₃H₈.

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What is a coefficient in a chemical equation?

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A coefficient is a number placed in front of a chemical formula to indicate how many molecules or moles of that substance are involved in the reaction.

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What is an example of an endothermic reaction?

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An example of an endothermic reaction is photosynthesis, where plants absorb energy from sunlight.

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What is an example of an exothermic reaction?

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An example of an exothermic reaction is combustion, such as burning wood or gasoline, which releases heat.

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What is a chemical formula?

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A chemical formula is a way of expressing the composition of a substance using symbols for its constituent elements.