must a balanced chemical equation are three categories of chemical A chemical equation is a short easy way to show a chemical reaction. Chemical equations use chemical formulas and other symbols instead of words to summarize a reaction. All chemical equations have a common structure. A chemical equation tells you the substances you start with in a reaction and the substances you get at the end. The substances you have at the beginning are called the reactants. When the reaction is complete, you have new substances called the The formulas for the reactants are products. written on the left side of the equation, followed by an arrow ( ). You read the arrow as The formulas for “yields.” the products are written on the right side of the equation. When there are two or more reactants or products, they are separated by plus signs. The principle called conservation of mass was first demonstrated in the late 1700s. The principle of conservation of mass states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products. In an open system, matter can enter from or escape to the surroundings. A match burning in the air is an example of an open system. You cannot measure the mass of all the reactants and products in an open system. A closed system is a system in which matter cannot enter from or escape to the surroundings. A sealed plastic bag is an example of a closed system. A closed system allows you to measure the mass of all reactants and products in a reaction. To describe a reaction accurately, a chemical equation must show the same number of each type of atom on both sides of the equation. An equation is balanced when it accurately represents conservation of mass. To balance a chemical equation, you may have to use coefficients. A coefficient is a number placed in front of a chemical formula in an equation. It tells you how many atoms or molecules of a reactant or a product take part in the reaction. Many chemical reactions can be classified in one of three categories: synthesis, decomposition, or replacement. When two or more elements or compounds combine to make a more complex substance, the reaction is called a synthesis reaction. The reaction of hydrogen and oxygen to make water is a synthesis reaction. A reaction called a reaction breaks down compounds into simpler products. For example, hydrogen peroxide decomposition decomposes into water and oxygen gas. When one element replaces another in a compound, or when two elements in different compounds trade places, the reaction is called a replacement reaction.
must a balanced chemical equation are three categories of chemical A chemical equation is a short easy way to show a chemical reaction. Chemical equations use chemical formulas and other symbols instead of words to summarize a reaction. All chemical equations have a common structure. A chemical equation tells you the substances you start with in a reaction and the substances you get at the end. The substances you have at the beginning are called the reactants. When the reaction is complete, you have new substances called the products. The formulas for the reactants are written on the left side of the equation, followed by an arrow ( ). You read the arrow as “yields.” The formulas for the products are written on the right side of the equation. When there are two or more reactants or products, they are separated by plus signs. The principle called conservation of mass was first demonstrated in the late 1700s. The principle of conservation of mass states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products. In an open system, matter can enter from or escape to the surroundings. A match burning in the air is an example of an open system. You cannot measure the mass of all the reactants and products in an open system. A closed system is a system in which matter cannot enter from or escape to the surroundings. A sealed plastic bag is an example of a closed system. A closed system allows you to measure the mass of all reactants and products in a reaction. To describe a reaction accurately, a chemical equation must show the same number of each type of atom on both sides of the equation. An equation is balanced when it accurately represents conservation of mass. To balance a chemical equation, you may have to use coefficients. A coefficient is a number placed in front of a chemical formula in an equation. It tells you how many atoms or molecules of a reactant or a product take part in the reaction. Many chemical reactions can be classified in one of three categories: synthesis, decomposition, or replacement. When two or more elements or compounds combine to make a more complex substance, the reaction is called a synthesis reaction. The reaction of hydrogen and oxygen to make water is a synthesis reaction. A reaction called a decomposition reaction breaks down compounds into simpler products. For example, hydrogen peroxide decomposes into water and oxygen gas. When one element replaces another in a compound, or when two elements in different compounds trade places, the reaction is called a replacement reaction.