Question

Which of the following statements about chemical equations is (are) true? a. When balancing a chemical equation, you can never change the coefficient in front of any chemical formula. b. The coefficients in a balanced chemical equation refer to the number of grams of reactants and products. c. In a chemical equation, the reactants are on the right, and the products are on the left. d. When balancing a chemical equation, you can never change the subscripts of any chemical formula. e. In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation.

Short answer

The correct statements about chemical equations are: - Statement d: When balancing a chemical equation, you can never change the subscripts of any chemical formula. - Statement e: In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation.

Step-by-step solution

Statement a:

When balancing a chemical equation, you can never change the coefficient in front of any chemical formula. This statement is false. To balance a chemical equation, you need to adjust the coefficients in front of the chemical formulas to ensure that the number of atoms of each element is equal on both the reactant and the product side.

Statement b:

The coefficients in a balanced chemical equation refer to the number of grams of reactants and products. This statement is also false. The coefficients refer to the relative number of moles (not grams) of the reactants and products in a balanced chemical equation.

Statement c:

In a chemical equation, the reactants are on the right, and the products are on the left. This statement is incorrect. In a chemical equation, the reactants are traditionally written on the left side, and the products are written on the right side. The arrow (→) in the equation separates the reactants from the products and symbolizes the direction of the reaction.

Statement d:

When balancing a chemical equation, you can never change the subscripts of any chemical formula. This statement is true. In order to balance a chemical equation, you should only adjust the coefficients in front of the chemical formulas. Changing the subscripts would alter the chemical identity of the substances involved in the reaction, which is not allowed.

Statement e:

In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation. This statement is true. This principle, known as the Law of Conservation of Mass, is a fundamental concept in chemistry. It means that the total mass of reactants in a chemical reaction must equal the total mass of the products formed. Consequently, a balanced chemical equation must have an equal number of atoms for each element on both sides of the equation. To sum it up, the true statements about chemical equations are: - Statement d: When balancing a chemical equation, you can never change the subscripts of any chemical formula. - Statement e: In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation.

Key concepts

Law of Conservation of Mass

The Law of Conservation of Mass is a cornerstone in the world of chemistry. It dictates that matter is neither created nor destroyed during a chemical reaction. This principle has profound implications when balancing chemical equations.

When a chemical reaction takes place, the total mass of the substances before the reaction must equal the total mass of the substances after the reaction. This means you'll end up with the same quantity of each type of atom on both sides of the equation.

Here's why this is vital: chemistry seeks to describe and predict how substances interact. Ensuring mass conservation helps preserve accuracy and reliability in these predictions.

• Your reactants are the substances you start with in a reaction.
• The products are what you achieve. They appear on the right side of the equation.
• The arrow indicates the direction of the reaction from reactants to products.

Only by balancing equations can chemists remain true to the law and accurately represent what happens at the atomic level.

Coefficients in Chemical Equations

In a balanced chemical equation, coefficients play a crucial role. They are the numbers placed before molecules and compounds to indicate how many units of each are involved. Adjusting these coefficients ensures each element has an equal number of atoms on both sides of the equation.

Coefficients tell us the relative amount of substances involved in the reaction. They reflect the stoichiometry of the reaction, which is the quantitative relationship between reactants and products.

It’s crucial not to confuse coefficients with subscripts. Subscripts form part of the chemical formula, denoting the number of atoms in a molecule and should never be changed when balancing equations.

For example, in the water formation reaction:
H_2 + O_2 → H_2O,
you might need coefficients like, 2H_2 + O_2 → 2H_2O, to balance the equation, reflecting the stoichiometric balance needed to conserve mass.

Chemical Reaction Fundamentals

Understanding the basics of a chemical reaction is essential. Reactions depict how substances (reactants) change into other substances (products). They can release or absorb energy and involve breaking and forming bonds.

Here's how a chemical equation is arranged:

• Reactants are on the left side.
• Products are on the right side.
• An arrow (→) separates the two sides, showing the flow of the reaction.

This format lets chemists communicate complex reaction details with simplicity.

Chemical reactions can vary. They might involve simple or complex transformations. But the fundamentals like maintaining equal mass and properly using coefficients remain constant.

By understanding these fundamentals, you'll grasp how chemicals interact and change, forming the amazing world of chemistry.