Physical Science

What does the law of conservation of mass state?

The total mass of the reactants before a chemical reaction is the same as the total mass of the products after the chemical reaction.

What is a chemical equation?

A description of a reaction using element symbols and chemical formulas.

What are reactants and products in a chemical reaction?

Reactants are the starting substances, while products are the substances produced by the chemical reaction.

How are reactants and products written in a chemical equation?

Reactants are written to the left of an arrow, and products are written to the right; they are separated by plus signs.

How do bonds break and new bonds form during a chemical reaction?

Atoms rearrange when bonds break, colliding with enough energy to separate and form new bonds.

What are physical changes?

Physical changes do not produce new substances, and the substances remain the same despite changes in physical properties.

What are chemical changes?

Chemical changes result in one or more new substances with different physical and chemical properties; also called chemical reactions.

What is an example of a change in properties during a chemical reaction?

Change in color, formation of bubbles, change in odor, or formation of a precipitate.

What is a synthesis reaction?

A chemical reaction where two or more substances combine to form one compound.

What is a decomposition reaction?

A reaction in which one compound breaks down into two or more substances.

What occurs in a single replacement reaction?

One element replaces another element in a compound.

What occurs in a double replacement reaction?

Anions and cations exchange between two compounds, forming two new compounds.

What is a combustion reaction?

A chemical reaction where a substance combines with oxygen and releases energy.

What is an inhibitor?

A substance that slows down or stops a chemical reaction.

What is a catalyst?

A substance that increases reaction rate by lowering the activation energy.

What are enzymes?

Hormones that act as catalysts to speed up chemical reactions in living cells.

What is the reaction rate?

The speed at which a chemical reaction occurs.

What factor increases reaction rate by increasing collisions?

concentration

How does temperature affect reaction rate?

Higher temperatures increase the average speed of particles, leading to more frequent and energetic collisions.

What is activation energy?

The minimum amount of energy needed to start a chemical reaction.

What are exothermic reactions?

Chemical reactions that release thermal energy.

What are endothermic reactions?

Chemical reactions that absorb thermal energy and require continuous energy input to proceed.